diff --git a/Source/HBIOS/ch.asm b/Source/HBIOS/ch.asm
index 9eae6985..ad884da4 100644
--- a/Source/HBIOS/ch.asm
+++ b/Source/HBIOS/ch.asm
@@ -8,23 +8,10 @@
 ; Thanks and credit to Alan Cox.  Much of this driver is based on
 ; his code in FUZIX (https://github.com/EtchedPixels/FUZIX).
 ;
-; NOTES:
-;  - There seem to be compatibility issues with older USB thumb drives.
-;    Such drives will complete DISK_INIT successfully, but then return
-;    an error attempting to do any I/O.  The error is $17 indicating
-;    the CH37x encountered an overflow during communication with the
-;    device.   I found that adding a DISK_MOUNT command (only possible
-;    on CH376) resolved the issue for some devices, so that has been
-;    added to the RESET routine when using CH376.
-;
-; TODO:
-;  - Implement auto-recovery on error status?
-;  - !!! Move CH_MODE to config variable !!!
-;
-; PORT OFFSETS FROM BASE PORT
-;
-;CH_DATA	.EQU	0		; DATA PORT AT BASE + 0
-;CH_CMD		.EQU	1		; CMD PORT AT BASE + 1
+; This file is the core driver file for the CH37x devices.  Since the
+; CH376 supports both a USB Drive interface and an SD Card interface,
+; the code for these interfaces is included as needed.  See
+; chusb.asm and chsd.asm.
 ;
 ; CH DEVICE TYPES
 ;
@@ -77,6 +64,21 @@ CH_CMD_DSKWRGO	.EQU	$57		; CONTINUE DISK WRITE
 CH_CMD_DSKINQ	.EQU	$58		; DISK INQUIRY
 CH_CMD_DSKRDY	.EQU	$59		; DISK READY
 ;
+; SUB-DRIVER SETUP
+;
+CHUSBENABLE	.EQU	((CH0USBENABLE == TRUE) | (CH1USBENABLE == TRUE))
+CHSDENABLE	.EQU	((CH0SDENABLE == TRUE) | (CH1SDENABLE == TRUE))
+;
+#IF (!CHUSBENABLE)
+CHUSB_CFG0	.EQU	0		; DUMMY ENTRY
+CHUSB_CFG1	.EQU	0		; DUMMY ENTRY
+#ENDIF
+;
+#IF (!CHSDENABLE)
+CHSD_CFG0	.EQU	0		; DUMMY ENTRY
+CHSD_CFG1	.EQU	0		; DUMMY ENTRY
+#ENDIF
+;
 ; CH DEVICE CONFIGURATION
 ;
 CH_CFGSIZ	.EQU	9		; SIZE OF CFG TBL ENTRIES
@@ -153,14 +155,17 @@ CH_INIT2:
 	CALL	PRTHEXBYTE		; DISPLAY IT
 ;
 	XOR	A			; UNKNOWN MODE
-	LD	(CH_MODE),A		; SAVE IT
+	LD	(CH0_MODE),A		; SAVE IT
+	LD	(CH1_MODE),A		; SAVE IT
 	;CALL	CH_FLUSH		; FLUSH DEVICE OUTPUT QUEUE
 ;
-	; I AM ENCOUNTERING SOME CH376 CHIPS THAT GO HAYWIRE AFTER A
-	; RESET COMMAND.  THEY STOP RESPONDING FOR A VERY LONG TIME.
-	; I AM SEEING THIS ONLY ON "LC TECH" ADAPTERS AND ONLY ON Z80
-	; SYSTEMS (NOT Z180).  NO IDEA WHAT IS GOING ON, SO I AM
+	; VERSION 4 OF THE CH376 CHIPS ARE HAVING TROUBLE WITH THE
+	; RESET COMMAND.  ON Z80 SYSTEMS THEY TAKE A VERY LONG TIME
+	; TO RESET.  ON Z180 SYSTEMS, I AM NOT SEEING AN ISSUE.
+	; CH375 CHIPS AND VERSION 3 OF THE CH376 SEEM FINE (IN Z80
+	; OR Z180 SYSTEMS).  NO IDEA WHAT IS GOING ON, SO I AM
 	; GIVING UP FOR NOW AND REMOVING THE RESET.
+;
 	;CALL	CH_RESET		; FULL CH37X RESET
 ;
 	CALL	CH_DETECT		; DETECT CHIP PRESENCE
@@ -199,6 +204,7 @@ CH_INIT3A:
 	AND	$3F			; ISOLATE VERSION BITS
 	CALL	PRTHEXBYTE		; PRINT IT
 ;
+#IF (CHUSBENABLE)
 	; USB SUB-DRIVER INIT
 	LD	L,(IY+CH_USBCFG+0)	; LSB OF USB CFG ENTRY
 	LD	H,(IY+CH_USBCFG+1)	; MSB OF USB CFG ENTRY
@@ -207,7 +213,9 @@ CH_INIT3A:
 	OR	A			; SET FLAGS
 	CALL	NZ,CHUSB_INIT		; IF SO, DO USB INIT
 	POP	IY			; RESTORE IY
+#ENDIF
 ;
+#IF (CHSDENABLE)
 	; SD CARD SUB-DRIVER INIT
 	LD	L,(IY+CH_SDCFG+0)	; LSB OF SD CFG ENTRY
 	LD	H,(IY+CH_SDCFG+1)	; MSB OF SD CFG ENTRY
@@ -216,6 +224,7 @@ CH_INIT3A:
 	OR	A			; SET FLAGS
 	CALL	NZ,CHSD_INIT		; IF SO, DO SD INIT
 	POP	IY			; RESTORE IY
+#ENDIF
 ;
 CH_INIT4:
 	LD	DE,CH_CFGSIZ		; SIZE OF CFG TABLE ENTRY
@@ -384,22 +393,33 @@ CH_GETVER:
 ; THE CH376 DOES NOT SEEM TO MAINTAIN SEPARATE OPERATING CONTEXTS FOR
 ; THE USB AND SD DEVICES.  IF BOTH ARE IN OPERATION, THEN A MODE
 ; SWITCH REQUIRES A COMPLETE REINITIALIZATION OF THE REQUESTED
-; DEVICE.
+; DEVICE.  THIS WHOLE MESS IS ONLY NEEDED IF BOTH CHSD AND CHUSB
+; ARE ENDABLED, SO IT IS CONDITIONAL.
 ;
 CH_SETMODE:
+#IF (CHUSBENABLE & CHSDENABLE)
 	PUSH	BC			; SAVE BC
 	PUSH	DE			; SAVE DE
 	PUSH	HL			; SAVE HL
 	;PRTS("\r\nSETMODE:$")		; *DEBUG*
-	LD	L,A			; SAVE REQUESTED MODE
-	LD	A,(CH_MODE)		; GET CURRENT MODE
 	;CALL	PC_SPACE		; *DEBUG*
 	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	L			; COMPARE
+	LD	E,A			; SAVE REQUESTED MODE
+;
+	; WARNING: CH_SETMODE IS CALLED BY THE SUB-DRIVERS, SO
+	; IY WILL BE A POINTER TO THE CONFIG BLOCK OF THE SUB-DRIVER.
+	; BY CONVENTION, THE LOCATION OF THE MODE BYTE FOR EACH
+	; SUB-DRIVER IS AT OFFSET 12 IN THE CONFIG BLOCK!
+	LD	L,(IY+12)		; GET MODE PTR (LSB)
+	LD	H,(IY+13)		; GET MODE PTR (MSB)
+	LD	A,(HL)			; GET CUR MODE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	E			; COMPARE
 	JR	Z,CH_SETMODE_Z		; IF EQUAL, DONE
 ;
 	; NEED TO CHANGE MODES
-	LD	A,L			; GET REQUESTED MODE
+	LD	A,E			; RECOVER REQUESTED MODE
 	CP	CH_MODE_USB		; USB?
 	JR	Z,CH_SETMODE_USB	; IF SO, DO IT
 	CP	CH_MODE_SD		; SD?
@@ -408,1447 +428,41 @@ CH_SETMODE:
 	JR	CH_SETMODE_Z		; BAIL OUT
 ;
 CH_SETMODE_USB:
+#IF (CHUSBENABLE)
 	CALL	CHUSB_RESET		; FULL USB STACK RESET
+#ENDIF
 	JR	CH_SETMODE_Z		; MOVE ON
 ;
 CH_SETMODE_SD:
+#IF (CHSDENABLE)
 	CALL	CHSD_RESET		; FULL SD STACK RESET
+#ENDIF
 	JR	CH_SETMODE_Z		; MOVE ON
 ;
 CH_SETMODE_Z:
 	POP	HL			; RECOVER HL
 	POP	DE			; RECOVER DE
 	POP	BC			; RECOVER BC
+#ENDIF
 	RET				; DONE
 ;
 ;
 ;
-CH_MODE		.DB	CH_MODE_UNK
+CH0_MODE	.DB	CH_MODE_UNK
+CH1_MODE	.DB	CH_MODE_UNK
 ;
 CH_STR_NOHW	.TEXT	" NOT PRESENT$"
 ;
 CH_STR_375	.TEXT	"CH375$"
 CH_STR_376	.TEXT	"CH376$"
 ;
-;==================================================================================================
-; CH375/376 USB SUB-DRIVER
-;==================================================================================================
-;
-CHUSB_FASTIO	.EQU	TRUE		; USE INIR/OTIR?
-;
-; CHUSB DEVICE STATUS
-;
-CHUSB_STOK	.EQU	0
-CHUSB_STNOMEDIA	.EQU	-1
-CHUSB_STCMDERR	.EQU	-2
-CHUSB_STIOERR	.EQU	-3
-CHUSB_STTO	.EQU	-4
-CHUSB_STNOTSUP	.EQU	-5
-;
-; CHUSB DEVICE CONFIGURATION
-;
-CHUSB_CFGSIZ	.EQU	12		; SIZE OF USB CFG TBL ENTRIES
-;
-; CONFIG ENTRY DATA OFFSETS
-;
-; FIRST 3 BYTES SAME AS CH CONFIG
-CHUSB_STAT	.EQU	3		; LAST STATUS (BYTE)
-CHUSB_MEDCAP	.EQU	4		; MEDIA CAPACITY (DWORD)
-CHUSB_LBA	.EQU	8		; CURRENT LBA (DWORD)
-;
-CHUSB_CFGTBL:
-;
-#IF (CHCNT >= 1)
-CHUSB_CFG0:
-	.DB	0			; DEV NUM, FILLED DYNAMICALLY
-	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
-	.DB	CH0BASE			; IO BASE ADDRESS
-	.DB	0			; DEVICE STATUS
-	.DW	0,0			; DEVICE CAPACITY
-	.DW	0,0			; CURRENT LBA
-;
-  #IF (CH0USBENABLE)
-	.ECHO	"CHUSB: IO="
-	.ECHO	CH0BASE
-	.ECHO	"\n"
-  #ENDIF
-#ENDIF
-;
-#IF (CHCNT >= 2)
-CHUSB_CFG1:
-	.DB	0			; DEV NUM
-	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
-	.DB	CH1BASE			; IO BASE ADDRESS
-	.DB	0			; DEVICE STATUS
-	.DW	0,0			; DEVICE CAPACITY
-	.DW	0,0			; CURRENT LBA
-;
-  #IF (CH1USBENABLE)
-	.ECHO	"CHUSB: IO="
-	.ECHO	CH1BASE
-	.ECHO	"\n"
-  #ENDIF
-#ENDIF
-;
-#IF ($ - CHUSB_CFGTBL) != (CHCNT * CHUSB_CFGSIZ)
-	.ECHO	"*** INVALID CHUSB CONFIG TABLE ***\n"
-#ENDIF
-;
-	.DB	$FF			; END OF TABLE MARKER
-;
-;
-;
-CHUSB_INIT:
-	LD	A,(IY+CH_TYPE)		; GET DEVICE TYPE
-	PUSH	HL			; COPY INCOMING HL
-	POP	IY			; ... TO IY
-	LD	(IY+CH_TYPE),A		; SAVE DEVICE TYPE
-;
-	; UPDATE DRIVER RELATIVE UNIT NUMBER IN CONFIG TABLE
-	LD	A,(CHUSB_DEVNUM)	; GET NEXT UNIT NUM TO ASSIGN
-	LD	(IY+CH_DEV),A		; UPDATE IT
-	INC	A			; BUMP TO NEXT UNIT NUM TO ASSIGN
-	LD	(CHUSB_DEVNUM),A	; SAVE IT
-;
-	; ADD UNIT TO GLOBAL DISK UNIT TABLE
-	LD	BC,CHUSB_FNTBL		; BC := FUNC TABLE ADR
-	PUSH	IY			; CFG ENTRY POINTER
-	POP	DE			; COPY TO DE
-	CALL	DIO_ADDENT		; ADD ENTRY TO GLOBAL DISK DEV TABLE
-;
-	CALL	CHUSB_RESET		; RESET & DISCOVER MEDIA
-#IF (CHUSBTRACE <= 1)
-	CALL	NZ,CHUSB_PRTSTAT
-#ENDIF
-	RET	NZ			; ABORT ON FAILURE
-;
-	; START PRINTING DEVICE INFO
-	CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
-;
-	; PRINT STORAGE CAPACITY (BLOCK COUNT)
-	PRTS(" BLOCKS=0x$")		; PRINT FIELD LABEL
-	LD	A,CHUSB_MEDCAP		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	LD32			; GET THE CAPACITY VALUE
-	CALL	PRTHEX32		; PRINT HEX VALUE
-;
-	; PRINT STORAGE SIZE IN MB
-	PRTS(" SIZE=$")			; PRINT FIELD LABEL
-	LD	B,11			; 11 BIT SHIFT TO CONVERT BLOCKS --> MB
-	CALL	SRL32			; RIGHT SHIFT
-	CALL	PRTDEC32		; PRINT DWORD IN DECIMAL
-	PRTS("MB$")			; PRINT SUFFIX
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; DRIVER FUNCTION TABLE
-;
-CHUSB_FNTBL:
-	.DW	CHUSB_STATUS
-	.DW	CHUSB_RESET
-	.DW	CHUSB_SEEK
-	.DW	CHUSB_READ
-	.DW	CHUSB_WRITE
-	.DW	CHUSB_VERIFY
-	.DW	CHUSB_FORMAT
-	.DW	CHUSB_DEVICE
-	.DW	CHUSB_MEDIA
-	.DW	CHUSB_DEFMED
-	.DW	CHUSB_CAP
-	.DW	CHUSB_GEOM
-#IF (($ - CHUSB_FNTBL) != (DIO_FNCNT * 2))
-	.ECHO	"*** INVALID CHUSB FUNCTION TABLE ***\n"
-#ENDIF
-;
-CHUSB_VERIFY:
-CHUSB_FORMAT:
-CHUSB_DEFMED:
-	SYSCHKERR(ERR_NOTIMPL)		; NOT IMPLEMENTED
-	RET
-;
-;
-;
-CHUSB_READ:
-	LD	A,CH_MODE_USB		; REQUEST USB MODE
-	CALL	CH_SETMODE		; DO IT
-	JP	NZ,CHUSB_CMDERR		; HANDLE ERROR
-;
-	CALL	HB_DSKREAD		; HOOK HBIOS DISK READ SUPERVISOR
-	LD	(CHUSB_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
-	LD	A,CH_CMD_DSKRD		; DISK READ COMMAND
-	CALL	CHUSB_RWSTART		; SEND CMD AND LBA
-;
-	; READ THE SECTOR IN 64 BYTE CHUNKS
-	LD	B,8			; 8 CHUNKS OF 64 FOR 512 BYTE SECTOR
-	LD	HL,(CHUSB_DSKBUF)	; GET DISK BUF ADR
-CHUSB_READ1:
-	CALL	CH_POLL			; WAIT FOR DATA READY
-	CP	$1D			; DATA READY TO READ?
-	;CALL	PC_LT			; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	JP	NZ,CHUSB_IOERR		; HANDLE IO ERROR
-	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
-	CALL	CH_RD			; READ DATA BLOCK LENGTH
-	CP	64			; AS EXPECTED?
-	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
-;
-#IF (CHUSB_FASTIO)
-	; READ 64 BYTE CHUNK
-	PUSH	BC			; SAVE LOOP CONTROL
-	LD	B,64			; READ 64 BYTES
-	LD	C,(IY+CH_IOBASE)	; BASE PORT
-	INIR				; DO IT FAST
-	POP	BC			; RESTORE LOOP CONTROL
-#ELSE
-	; BYTE READ LOOP
-	PUSH	BC			; SAVE LOOP CONTROL
-	LD	B,64			; READ 64 BYTES
-CHUSB_READ2:
-	CALL	CH_RD			; GET NEXT BYTE
-	LD	(HL),A			; SAVE IT
-	INC	HL			; INC BUF PTR
-	DJNZ	CHUSB_READ2		; LOOP AS NEEDED
-	POP	BC			; RESTORE LOOP CONTROL
-#ENDIF
-;
-	; PREPARE FOR NEXT CHUNK
-	LD	A,CH_CMD_DSKRDGO	; CONTINUE DISK READ
-	CALL	CH_CMD			; SEND IT
-	DJNZ	CHUSB_READ1		; LOOP TILL DONE
-;
-	; FINAL CHECK FOR COMPLETION & SUCCESS
-	CALL	CH_POLL			; WAIT FOR COMPLETION
-	CP	$14			; SUCCESS?
-	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
-;
-	; INCREMENT LBA
-	PUSH	HL			; SAVE HL
-	LD	A,CHUSB_LBA		; LBA OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	INC32HL			; INCREMENT THE VALUE
-	POP	HL			; RESTORE HL
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-;
-;
-CHUSB_WRITE:
-	LD	A,CH_MODE_USB		; REQUEST USB MODE
-	CALL	CH_SETMODE		; DO IT
-	JP	NZ,CHUSB_CMDERR		; HANDLE ERROR
-;
-	CALL	HB_DSKWRITE		; HOOK HBIOS DISK WRITE SUPERVISOR
-	LD	(CHUSB_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
-	LD	A,CH_CMD_DSKWR		; DISK READ COMMAND
-	CALL	CHUSB_RWSTART		; SEND CMD AND LBA
-;
-	; WRITE THE SECTOR IN 64 BYTE CHUNKS
-	LD	B,8			; 8 CHUNKS OF 64 FOR 512 BYTE SECTOR
-	LD	HL,(CHUSB_DSKBUF)	; GET DISK BUF ADR
-CHUSB_WRITE1:
-	CALL	CH_POLL			; WAIT FOR DATA READY
-	CP	$1E			; DATA READY TO WRITE
-	;CALL	PC_GT			; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	JP	NZ,CHUSB_IOERR		; HANDLE IO ERROR
-	CALL	CH_CMD_WR		; SEND WRITE USB DATA CMD
-	LD	A,64			; 64 BYTE CHUNK
-	CALL	CH_WR			; SEND DATA BLOCK LENGTH
-;
-#IF (CHUSB_FASTIO)
-	; WRITE 64 BYTE CHUNK
-	PUSH	BC			; SAVE LOOP CONTROL
-	LD	B,64			; WRITE 64 BYTES
-	LD	C,(IY+CH_IOBASE)	; BASE PORT
-	OTIR				; DO IT FAST
-	POP	BC			; RESTORE LOOP CONTROL
-#ELSE
-	; BYTE WRITE LOOP
-	PUSH	BC			; SAVE LOOP CONTROL
-	LD	B,64			; WRITE 64 BYTES
-CHUSB_WRITE2:
-	LD	A,(HL)			; GET NEXT BYTE
-	INC	HL			; INC BUF PTR
-	CALL	CH_WR			; WRITE NEXT BYTE
-	DJNZ	CHUSB_WRITE2		; LOOP AS NEEDED
-	POP	BC			; RESTORE LOOP CONTROL
-#ENDIF
-;
-	; PREPARE FOR NEXT CHUNK
-	LD	A,CH_CMD_DSKWRGO	; CONTINUE DISK READ
-	CALL	CH_CMD			; SEND IT
-	DJNZ	CHUSB_WRITE1		; LOOP TILL DONE
-;
-	; FINAL CHECK FOR COMPLETION & SUCCESS
-	CALL	CH_POLL			; WAIT FOR COMPLETION
-	CP	$14			; SUCCESS?
-	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
-;
-	; INCREMENT LBA
-	PUSH	HL			; SAVE HL
-	LD	A,CHUSB_LBA		; LBA OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	INC32HL			; INCREMENT THE VALUE
-	POP	HL			; RESTORE HL
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; INITIATE A DISK SECTOR READ/WRITE OPERATION
-; A: READ OR WRITE OPCODE
-;
-CHUSB_RWSTART:
-	CALL	CH_CMD			; SEND R/W COMMAND
-;
-	; SEND LBA, 4 BYTES, LITTLE ENDIAN
-	LD	A,CHUSB_LBA		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	LD	B,4			; SEND 4 BYTES
-CHUSB_RWSTART1:
-	LD	A,(HL)			; GET BYTE
-	INC	HL			; BUMP PTR
-	CALL	CH_WR			; SEND BYTE
-	DJNZ	CHUSB_RWSTART1		; LOOP AS NEEDED
-;
-	; REQUEST 1 SECTOR
-	LD	A,1			; 1 SECTOR
-	CALL	CH_WR			; SEND IT
-	RET
-;
-;
-;
-CHUSB_STATUS:
-	; RETURN UNIT STATUS
-	LD	A,(IY+CHUSB_STAT)	; GET STATUS OF SELECTED DEVICE
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-; RESET THE INTERFACE AND REDISCOVER MEDIA
-;
-CHUSB_RESET:
-	;PRTS("\n\rRES USB:$")		; *DEBUG*
-	;CALL	CH_FLUSH		; DISCARD ANY GARBAGE
-	;CALL	CH_RESET		; FULL CH37X RESET
-;
-	; RESET THE BUS
-	LD	A,CH_CMD_MODE		; SET MODE COMMAND
-	CALL	CH_CMD			; SEND IT
-	LD	A,7			; RESET BUS
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP			; SMALL WAIT
-	CALL	CH_RD			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CALL	CH_NAP			; SMALL WAIT
-;
-	; ACTIVATE USB MODE
-	LD	A,CH_CMD_MODE		; SET MODE COMMAND
-	CALL	CH_CMD			; SEND IT
-	LD	A,6			; USB ENABLED, SEND SOF
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP			; SMALL WAIT
-	CALL	CH_RD			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CALL	CH_NAP			; SMALL WAIT
-;
-	LD	A,CH_MODE_USB		; WE ARE NOW IN USB MODE
-	LD	(CH_MODE),A		; SAVE IT
-;
-	; INITIALIZE DISK
-	LD	B,24			; TRY A FEW TIMES
-CHUSB_RESET1:
-	;PRTS("\n\rDSKINIT:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKINIT	; DISK INIT COMMAND
-	CALL	CH_CMD			; SEND IT
-	LD	DE,10000		; 10000 * 16 = 160US ???
-	LD	DE,20000		; 10000 * 16 = 160US ???
-	LD	DE,12500		; 1250 * 16 = 200US ???
-	CALL	VDELAY			; DELAY
-	CALL	CH_POLL			; WAIT FOR RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; SUCCESS?
-	JR	Z,CHUSB_RESET1A		; IF SO, CHECK READY
-	CP	$16			; NO MEDIA
-	JP	Z,CHUSB_NOMEDIA		; HANDLE IT
-	CALL	CH_NAP			; SMALL DELAY
-	DJNZ	CHUSB_RESET1		; LOOP AS NEEDED
-	JP	CHUSB_TO		; HANDLE TIMEOUT
-;
-CHUSB_RESET1A:
-	;CALL	CHUSB_DSKRES		; DISK RESET
-	;CP	$14			; GOOD?
-	;JR	Z,CHUSB_RESET2
-	;CALL	CHUSB_DSKRDY		; CHECK IF DISK READY
-	;CP	$14			; GOOD?
-	;JR	Z,CHUSB_RESET2		; IF SO, MOVE ON
-	;DJNZ	CHUSB_RESET1		; KEEP TRYING
-;
-CHUSB_RESET2:
-	; USE OF CH376 DISK_MOUNT COMMAND SEEMS TO IMPROVE
-	; COMPATIBILITY WITH SOME OLDER USB THUMBDRIVES.
-	LD	A,(IY+CH_TYPE)		; CH37X TYPE?
-	CP	CHTYP_376		; IS CH376?
-	CALL	Z,CHUSB_DSKMNT		; IF SO, TRY MOUNT, IGNORE ERRS
-	;CALL	CHUSB_AUTOSET		; *DEBUG*
-	;CALL	CHUSB_TSTCON		; *DEBUG*
-	;CALL	CHUSB_MAXLUN		; *DEBUG*
-	;CALL	CHUSB_DSKRDY		; *DEBUG*
-	;CALL	CHUSB_DSKINQ		; *DEBUG*
-;;
-	CALL	CHUSB_DSKSIZ		; GET AND RECORD DISK SIZE
-	RET	NZ			; ABORT ON ERROR
-;
-	; SET STATUS AND RETURN
-	XOR	A			; CLEAR STATUS
-	LD	(IY+CHUSB_STAT),A	; RECORD STATUS
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-;
-;
-CHUSB_DEVICE:
-	LD	D,DIODEV_CHUSB		; D := DEVICE TYPE
-	LD	E,(IY+CH_DEV)		; E := PHYSICAL DEVICE NUMBER
-	LD	C,%00110011		; USB HARD DISK ATTRIBUTES
-	LD	H,(IY+CH_TYPE)		; H := MODE
-	LD	L,(IY+CH_IOBASE)	; L := BASE I/O ADDRESS
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; CHUSB_GETMED
-;
-CHUSB_MEDIA:
-	LD	A,E			; GET FLAGS
-	OR	A			; SET FLAGS
-	JR	Z,CHUSB_MEDIA1		; JUST REPORT CURRENT STATUS AND MEDIA
-	CALL	CHUSB_RESET		; RESET CHUSB INTERFACE
-;
-CHUSB_MEDIA1:
-	LD	A,(IY+CHUSB_STAT)	; GET STATUS
-	OR	A			; SET FLAGS
-	LD	D,0			; NO MEDIA CHANGE DETECTED
-	LD	E,MID_HD		; ASSUME WE ARE OK
-	RET	Z			; RETURN IF GOOD INIT
-	LD	E,MID_NONE		; SIGNAL NO MEDIA
-	LD	A,ERR_NOMEDIA		; NO MEDIA ERROR
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-;
-;
-CHUSB_SEEK:
-	BIT	7,D			; CHECK FOR LBA FLAG
-	CALL	Z,HB_CHS2LBA		; CLEAR MEANS CHS, CONVERT TO LBA
-	RES	7,D			; CLEAR FLAG REGARDLESS (DOES NO HARM IF ALREADY LBA)
-	LD	(IY+CHUSB_LBA+0),L	; SAVE NEW LBA
-	LD	(IY+CHUSB_LBA+1),H	; ...
-	LD	(IY+CHUSB_LBA+2),E	; ...
-	LD	(IY+CHUSB_LBA+3),D	; ...
-	XOR	A			; SIGNAL SUCCESS
-	RET				; AND RETURN
-;
-;
-;
-CHUSB_CAP:
-	LD	A,(IY+CHUSB_STAT)	; GET STATUS
-	PUSH	AF			; SAVE IT
-	LD	A,CHUSB_MEDCAP		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	LD32			; GET THE CURRENT CAPACITY INTO DE:HL
-	LD	BC,512			; 512 BYTES PER BLOCK
-	POP	AF			; RECOVER STATUS
-	OR	A			; SET FLAGS
-	RET
-;
-;
-;
-CHUSB_GEOM:
-	; FOR LBA, WE SIMULATE CHS ACCESS USING 16 HEADS AND 16 SECTORS
-	; RETURN HS:CC -> DE:HL, SET HIGH BIT OF D TO INDICATE LBA CAPABLE
-	CALL	CHUSB_CAP		; GET TOTAL BLOCKS IN DE:HL, BLOCK SIZE TO BC
-	LD	L,H			; DIVIDE BY 256 FOR # TRACKS
-	LD	H,E			; ... HIGH BYTE DISCARDED, RESULT IN HL
-	LD	D,16 | $80		; HEADS / CYL = 16, SET LBA CAPABILITY BIT
-	LD	E,16			; SECTORS / TRACK = 16
-	RET				; DONE, A STILL HAS CHUSB_CAP STATUS
-;
-; CH37X HELPER ROUTINES
-;
-;
-; PERFORM DISK MOUNT
-;
-CHUSB_DSKMNT:
-	;PRTS("\n\rMOUNT:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKMNT		; DISK QUERY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; SUCCESS?
-	RET	NZ			; ABORT IF NOT
-;
-#IF FALSE
-	CALL	CH_CMD_RD		; SEND READ COMMAND
-	CALL	CH_RD			; GET LENGTH
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	LD	B,A			; LOOP COUNTER
-	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
-CHUSB_DSKMNT1:
-	CALL	CH_RD			; GET A BYTE
-	LD	(HL),A			; SAVE IT
-	INC	HL			; BUMP BUF PTR
-	DJNZ	CHUSB_DSKMNT1		; LOOP FOR ALL DATA
-;
-	;LD	DE,HB_WRKBUF		; *DEBUG*
-	;CALL	DUMP_BUFFER		; *DEBUG*
-;
-	CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
-	LD	HL,HB_WRKBUF + 8
-	LD	B,28
-CHUSB_DSKMNT2:
-	LD	A,(HL)
-	INC	HL
-	CALL	COUT
-	DJNZ	CHUSB_DSKMNT2
-#ENDIF
-;
-	XOR	A
-	RET
-;
-; PERFORM DISK SIZE
-;
-CHUSB_DSKSIZ:
-	;PRTS("\n\rDSKSIZ:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKSIZ		; DISK SIZE COMMAND
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_POLL			; WAIT FOR RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; SUCCESS?
-	JP	NZ,CHUSB_CMDERR		; HANDLE CMD ERROR
-	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
-	CALL	CH_RD			; GET RD DATA LEN
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$08			; MAKE SURE IT IS 8
-	JP	NZ,CHUSB_CMDERR		; HANDLE CMD ERROR
-	LD	A,CHUSB_MEDCAP		; MEDIA CAPACITY OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	PUSH	HL			; SAVE ADDRESS
-	CALL	CH_RD
-	LD	D,A
-	CALL	CH_RD
-	LD	E,A
-	CALL	CH_RD
-	LD	H,A
-	CALL	CH_RD
-	LD	L,A
-	CALL	CH_RD
-	CALL	CH_RD
-	CALL	CH_RD
-	CALL	CH_RD
-	POP	BC			; RECOVER ADDRESS TO BC
-	CALL	ST32			; STORE IT
-	XOR	A			; SIGNAL SUCCESS
-	RET				; AND DONE
-;
-#IF FALSE
-;
-; PERFORM DISK INQUIRY
-; BASICALLY THE SCSI INQUIRY COMMAND
-;
-CHUSB_DSKINQ:
-	;PRTS("\n\rINQUIRY:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKINQ		; DISK QUERY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; SUCCESS?
-	RET	NZ			; ABORT IF NOT
-	CALL	CH_CMD_RD		; SEND READ COMMAND
-	CALL	CH_RD			; GET LENGTH
-	LD	B,A			; LOOP COUNTER
-	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
-DSKINQ1:
-	CALL	CH_RD			; GET A BYTE
-	LD	(HL),A			; SAVE IT
-	INC	HL			; BUMP BUF PTR
-	DJNZ	DSKINQ1			; LOOP FOR ALL DATA
-;
-	;LD	DE,HB_WRKBUF		; *DEBUG*
-	;CALL	DUMP_BUFFER		; *DEBUG*
-;
-	;CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
-	;LD	HL,HB_WRKBUF + 8
-	;LD	B,28
-DSKINQ2:
-	;LD	A,(HL)
-	;INC	HL
-	;CALL	COUT
-	;DJNZ	DSKINQ2
-;
-	RET
-;
-; PERFORM SET RETRIES
-;
-CHUSB_SETRETRY:
-	;PRTS("\n\rSETRETRY:$")		; *DEBUG*
-	LD	A,CH_CMD_SETRETRY	; DISK READY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_NAP
-	LD	A,$25			; CONSTANT
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP
-	LD	A,$BF			; MAX
-	CALL	CH_WR
-	CALL	CH_NAP
-	CALL	CH_RD			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-	RET
-;
-; PERFORM DISK RESET
-;
-CHUSB_DSKRES:
-	;PRTS("\n\rDSKRES:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKRES		; DISK READY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-	RET
-;
-; PERFORM DISK READY
-;
-CHUSB_DSKRDY:
-	;PRTS("\n\rDSKRDY:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKRDY		; DISK READY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; *DEBUG*
-	JR	NZ,CHUSB_DSKRDY		; *DEBUG*
-;
-	RET
-;
-; PERFORM AUTO SETUP
-;
-CHUSB_AUTOSET:
-	;PRTS("\n\rAUTOSET:$")		; *DEBUG*
-	LD	A,CH_CMD_AUTOSET	; AUTOMATIC SETUP FOR USB
-	CALL	CH_CMD			; DO IT
-	CALL	LDELAY			; *DEBUG*
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-	RET
-;
-; PERFORM TEST CONNECT
-;
-CHUSB_TSTCON:
-	;PRTS("\n\rTSTCON:$")		; *DEBUG*
-	LD	A,CH_CMD_TSTCON		; TEST USB DEVICE CONNECT
-	CALL	CH_CMD			; DO IT
-	CALL	CH_NAP			; WAIT A BIT
-	CALL	CH_RD			; GET RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-	RET
-;
-; PERFORM GET MAX LUN
-;
-CHUSB_MAXLUN:
-	;PRTS("\n\rMAXLUN:$")		; *DEBUG*
-	LD	A,CH_CMD_MAXLUN		; TEST USB DEVICE CONNECT
-	CALL	CH_CMD			; DO IT
-	CALL	CH_NAP			; WAIT A BIT
-	LD	A,$38			; CONSTANT
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP
-	CALL	CH_RD			; GET RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-	RET
-;
-#ENDIF
-;
-; ERROR HANDLERS
-;
-;
-CHUSB_NOMEDIA:
-	LD	A,CHUSB_STNOMEDIA
-	JR	CHUSB_ERR
-;
-CHUSB_CMDERR:
-	LD	A,CHUSB_STCMDERR
-	JR	CHUSB_ERR
-;
-CHUSB_IOERR:
-	LD	A,CHUSB_STIOERR
-	JR	CHUSB_ERR
+; INCLUDE SUB-DRIVERS AS NEEDED
 ;
-CHUSB_TO:
-	LD	A,CHUSB_STTO
-	JR	CHUSB_ERR
-;
-CHUSB_NOTSUP:
-	LD	A,CHUSB_STNOTSUP
-	JR	CHUSB_ERR
-;
-CHUSB_ERR:
-	LD	(IY+CHUSB_STAT),A	; SAVE NEW STATUS
-;
-CHUSB_ERR2:
-#IF (CHUSBTRACE >= 2)
-	CALL	CHUSB_PRTSTAT
+#IF (CHUSBENABLE)
+  #INCLUDE "chusb.asm"
 #ENDIF
-	OR	A			; SET FLAGS
-	RET
-;
-;
-;
-CHUSB_PRTERR:
-	RET	Z			; DONE IF NO ERRORS
-	; FALL THRU TO CHUSB_PRTSTAT
-;
-; PRINT FULL DEVICE STATUS LINE
-;
-CHUSB_PRTSTAT:
-	PUSH	AF
-	PUSH	DE
-	PUSH	HL
-	LD	A,(IY+CHUSB_STAT)
-	CALL	CHUSB_PRTPREFIX		; PRINT UNIT PREFIX
-	CALL	PC_SPACE		; FORMATTING
-	CALL	CHUSB_PRTSTATSTR
-	POP	HL
-	POP	DE
-	POP	AF
-	RET
-;
-; PRINT STATUS STRING
-;
-CHUSB_PRTSTATSTR:
-	PUSH	AF
-	PUSH	DE
-	PUSH	HL
-	LD	A,(IY+CHUSB_STAT)
-	NEG
-	LD	HL,CHUSB_STR_ST_MAP
-	ADD	A,A
-	CALL	ADDHLA
-	LD	E,(HL)
-	INC	HL
-	LD	D,(HL)
-	CALL	WRITESTR
-	POP	HL
-	POP	DE
-	POP	AF
-	RET
-;
-; PRINT DIAGNONSTIC PREFIX
-;
-CHUSB_PRTPREFIX:
-	PUSH	AF
-	CALL	NEWLINE
-	PRTS("CHUSB$")
-	LD	A,(IY+CH_DEV)		; GET CURRENT DEVICE NUM
-	CALL	PRTDECB
-	CALL	PC_COLON
-	POP	AF
-	RET
-;
-; DATA STORAGE
-;
-CHUSB_DEVNUM	.DB	0		; TEMP DEVICE NUM USED DURING INIT
-CHUSB_DSKBUF	.DW	0
-;
-CHUSB_STR_ST_MAP:
-	.DW		CHUSB_STR_STOK
-	.DW		CHUSB_STR_STNOMEDIA
-	.DW		CHUSB_STR_STCMDERR
-	.DW		CHUSB_STR_STIOERR
-	.DW		CHUSB_STR_STTO
-	.DW		CHUSB_STR_STNOTSUP
-;
-CHUSB_STR_STOK		.TEXT	"OK$"
-CHUSB_STR_STNOMEDIA	.TEXT	"NO MEDIA$"
-CHUSB_STR_STCMDERR	.TEXT	"COMMAND ERROR$"
-CHUSB_STR_STIOERR	.TEXT	"IO ERROR$"
-CHUSB_STR_STTO		.TEXT	"TIMEOUT$"
-CHUSB_STR_STNOTSUP	.TEXT	"NOT SUPPORTED$"
-CHUSB_STR_STUNK		.TEXT	"UNKNOWN ERROR$"
-;
-;==================================================================================================
-; CH375/376 SD CARD SUB-DRIVER
-;==================================================================================================
-;
-#DEFINE	CHSD_IMGFILE "DISK.IMG"
-;
-CHSD_FASTIO	.EQU	TRUE		; USE INIR/OTIR?
-;
-; CHUSB DEVICE STATUS
 ;
-CHSD_STOK	.EQU	0
-CHSD_STNOMEDIA	.EQU	-1
-CHSD_STCMDERR	.EQU	-2
-CHSD_STIOERR	.EQU	-3
-CHSD_STTO	.EQU	-4
-CHSD_STNOTSUP	.EQU	-5
-CHSD_STNOFILE	.EQU	-6
-;
-; CHSD DEVICE CONFIGURATION
-;
-CHSD_CFGSIZ	.EQU	12		; SIZE OF USB CFG TBL ENTRIES
-;
-; CONFIG ENTRY DATA OFFSETS
-;
-; FIRST 3 BYTES SAME AS CH CONFIG
-CHSD_STAT	.EQU	3		; LAST STATUS (BYTE)
-CHSD_MEDCAP	.EQU	4		; MEDIA CAPACITY (DWORD)
-CHSD_LBA	.EQU	8		; CURRENT LBA (DWORD)
-;
-CHSD_CFGTBL:
-;
-#IF (CHCNT >= 1)
-CHSD_CFG0:
-	.DB	0			; DEV NUM, FILLED DYNAMICALLY
-	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
-	.DB	CH0BASE			; IO BASE ADDRESS
-	.DB	0			; DEVICE STATUS
-	.DW	0,0			; DEVICE CAPACITY
-	.DW	0,0			; CURRENT LBA
-;
-  #IF (CH0SDENABLE)
-	.ECHO	"CHSD: IO="
-	.ECHO	CH0BASE
-	.ECHO	"\n"
-  #ENDIF
-#ENDIF
-;
-#IF (CHCNT >= 2)
-CHSD_CFG1:
-	.DB	0			; DEV NUM
-	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
-	.DB	CH1BASE			; IO BASE ADDRESS
-	.DB	0			; DEVICE STATUS
-	.DW	0,0			; DEVICE CAPACITY
-	.DW	0,0			; CURRENT LBA
-;
-  #IF (CH1SDENABLE)
-	.ECHO	"CHSD: IO="
-	.ECHO	CH1BASE
-	.ECHO	"\n"
-  #ENDIF
+#IF (CHSDENABLE)
+  #INCLUDE "chsd.asm"
 #ENDIF
 ;
-#IF ($ - CHSD_CFGTBL) != (CHCNT * CHSD_CFGSIZ)
-	.ECHO	"*** INVALID CHSD CONFIG TABLE ***\n"
-#ENDIF
-;
-	.DB	$FF			; END OF TABLE MARKER
-;
-;
-;
-CHSD_INIT:
-	LD	A,(IY+CH_TYPE)		; GET DEVICE TYPE
-	PUSH	HL			; COPY INCOMING HL
-	POP	IY			; ... TO IY
-	LD	(IY+CH_TYPE),A		; SAVE DEVICE TYPE
-;
-	; UPDATE DRIVER RELATIVE UNIT NUMBER IN CONFIG TABLE
-	LD	A,(CHSD_DEVNUM)		; GET NEXT UNIT NUM TO ASSIGN
-	LD	(IY+CH_DEV),A		; UPDATE IT
-	INC	A			; BUMP TO NEXT UNIT NUM TO ASSIGN
-	LD	(CHSD_DEVNUM),A		; SAVE IT
-;
-	; ADD UNIT TO GLOBAL DISK UNIT TABLE
-	LD	BC,CHSD_FNTBL		; BC := FUNC TABLE ADR
-	PUSH	IY			; CFG ENTRY POINTER
-	POP	DE			; COPY TO DE
-	CALL	DIO_ADDENT		; ADD ENTRY TO GLOBAL DISK DEV TABLE
-;
-	CALL	CHSD_RESET		; RESET & DISCOVER MEDIA
-#IF (CHSDTRACE <= 1)
-	CALL	NZ,CHSD_PRTSTAT
-#ENDIF
-	RET	NZ			; ABORT ON FAILURE
-;
-	; START PRINTING DEVICE INFO
-	CALL	CHSD_PRTPREFIX		; PRINT DEVICE PREFIX
-;
-	; PRINT STORAGE CAPACITY (BLOCK COUNT)
-	PRTS(" BLOCKS=0x$")		; PRINT FIELD LABEL
-	LD	A,CHSD_MEDCAP		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	LD32			; GET THE CAPACITY VALUE
-	CALL	PRTHEX32		; PRINT HEX VALUE
-;
-	; PRINT STORAGE SIZE IN MB
-	PRTS(" SIZE=$")			; PRINT FIELD LABEL
-	LD	B,11			; 11 BIT SHIFT TO CONVERT BLOCKS --> MB
-	CALL	SRL32			; RIGHT SHIFT
-	CALL	PRTDEC32		; PRINT DWORD IN DECIMAL
-	PRTS("MB$")			; PRINT SUFFIX
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; DRIVER FUNCTION TABLE
-;
-CHSD_FNTBL:
-	.DW	CHSD_STATUS
-	.DW	CHSD_RESET
-	.DW	CHSD_SEEK
-	.DW	CHSD_READ
-	.DW	CHSD_WRITE
-	.DW	CHSD_VERIFY
-	.DW	CHSD_FORMAT
-	.DW	CHSD_DEVICE
-	.DW	CHSD_MEDIA
-	.DW	CHSD_DEFMED
-	.DW	CHSD_CAP
-	.DW	CHSD_GEOM
-#IF (($ - CHSD_FNTBL) != (DIO_FNCNT * 2))
-	.ECHO	"*** INVALID CHSD FUNCTION TABLE ***\n"
-#ENDIF
-;
-CHSD_VERIFY:
-CHSD_FORMAT:
-CHSD_DEFMED:
-	SYSCHKERR(ERR_NOTIMPL)		; NOT IMPLEMENTED
-	RET
-;
-;
-;
-CHSD_READ:
-	LD	A,CH_MODE_SD		; REQUEST SD MODE
-	CALL	CH_SETMODE		; DO IT
-	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
-;
-	CALL	HB_DSKREAD		; HOOK HBIOS DISK READ SUPERVISOR
-	LD	(CHSD_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
-	CALL	CHSD_RWSTART		; SET LBA OFFSET
-	RET	NZ
-;
-	;PRTS("\n\rREAD:$")		; *DEBUG*
-	LD	A,CH_CMD_BYTERD		; BYTE READ
-	CALL	CH_CMD			; SEND COMMAND
-	CALL	CH_NAP
-	LD	A,0			; LSB
-	CALL	CH_WR			; SEND IT
-	LD	A,2			; MSB
-	CALL	CH_WR			; SEND IT
-	CALL	CH_POLL			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$1D			; DATA READY TO READ?
-	JP	NZ,CHSD_IOERR		; HANDLE I/O ERROR
-;
-	LD	HL,(CHSD_DSKBUF)
-CHSD_READ1:
-	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
-	CALL	CH_RD			; GET DATA LENGTH
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-#IF (CHSD_FASTIO)
-	LD	B,A			; BYTE COUNT TO READ
-	LD	C,(IY+CH_IOBASE)	; BASE PORT
-	INIR				; DO IT FAST
-#ELSE
-	LD	B,A			; SAVE IT
-CHSD_READ2:
-	CALL	CH_RD			; GET DATA BYTE
-	LD	(HL),A			; SAVE IN BUFFER
-	INC	HL			; INC BUF PTR
-	DJNZ	CHSD_READ2		; LOOP TILL DONE W/ ALL BYTES
-#ENDIF
-;
-	LD	A,CH_CMD_BYTERDGO	; BYTE READ GO COMMAND
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_NAP
-	CALL	CH_POLL			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$1D			; MORE?
-	JR	Z,CHSD_READ1		; IF SO, GET MORE
-	CP	$14			; GOOD FINISH?
-	JP	NZ,CHSD_IOERR		; HANDLE ERROR
-;
-	; INCREMENT LBA
-	PUSH	HL			; SAVE HL
-	LD	A,CHSD_LBA		; LBA OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	INC32HL			; INCREMENT THE VALUE
-	POP	HL			; RESTORE HL
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-;
-;
-CHSD_WRITE:
-	LD	A,CH_MODE_SD		; REQUEST SD MODE
-	CALL	CH_SETMODE		; DO IT
-	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
-;
-	CALL	HB_DSKWRITE		; HOOK HBIOS DISK WRITE SUPERVISOR
-	LD	(CHSD_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
-	CALL	CHSD_RWSTART		; SET LBA OFFSET'
-	RET	NZ
-;
-	;PRTS("\n\rWRITE:$")		; *DEBUG*
-	LD	A,CH_CMD_BYTEWR		; BYTE WRITE
-	CALL	CH_CMD			; SEND COMMAND
-	LD	A,0			; LSB
-	CALL	CH_WR			; SEND IT
-	LD	A,2			; MSB
-	CALL	CH_WR			; SEND IT
-	CALL	CH_POLL			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$1E			; DATA READY TO GO?
-	JP	NZ,CHSD_IOERR		; HANDLE I/O ERROR
-;
-	LD	HL,(CHSD_DSKBUF)
-CHSD_WRITE1:
-	LD	A,CH_CMD_WRREQDAT	; WRITE REQUESTED DATA CMD
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_RD			; GET DATA LENGTH
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-;
-#IF (CHSD_FASTIO)
-	LD	B,A			; BYTE COUNT TO WRITE
-	LD	C,(IY+CH_IOBASE)	; BASE PORT
-	OTIR				; DO IT FAST
-#ELSE
-	LD	B,A			; SAVE IT
-CHSD_WRITE2:
-	CALL	CH_WR			; WRITE DATA BYTE
-	LD	(HL),A			; SAVE IN BUFFER
-	INC	HL			; INC BUF PTR
-	DJNZ	CHSD_WRITE2		; LOOP TILL DONE W/ ALL BYTES
-#ENDIF
-;
-	LD	A,CH_CMD_BYTEWRGO	; BYTE WRITE GO COMMAND
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_NAP
-	CALL	CH_POLL			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$1E			; MORE?
-	JR	Z,CHSD_WRITE1		; IF SO, SEND MORE
-	CP	$14			; GOOD FINISH?
-	JP	NZ,CHSD_IOERR		; HANDLE ERROR
-;
-	; INCREMENT LBA
-	PUSH	HL			; SAVE HL
-	LD	A,CHSD_LBA		; LBA OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	INC32HL			; INCREMENT THE VALUE
-	POP	HL			; RESTORE HL
-;
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; SEEK TO CURRENT LBA
-;
-CHSD_RWSTART:
-	;PRTS("\n\rRWST:$")		; *DEBUG*
-	LD	A,CH_CMD_BYTE_LOC	; BYTE LOCATE COMMAND (SEEK)
-	CALL	CH_CMD			; SEND IT
-;
-	; GET CURRENT LBA OFFSET
-	LD	A,CHSD_LBA		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	LD32			; OFFSET = DE:HL
-;
-	; CONVERT OFFSET FROM LBA TO BYTE
-	LD	B,9
-CHSD_RWSTART1:
-	SLA	L
-	RL	H
-	RL	E
-	RL	D
-	DJNZ	CHSD_RWSTART1
-	;CALL	PRTHEX32		; *DEBUG*
-;
-	; SEND THE BYTE OFFSET (LSB FIRST)
-	LD	A,L
-	CALL	CH_WR
-	LD	A,H
-	CALL	CH_WR
-	LD	A,E
-	CALL	CH_WR
-	LD	A,D
-	CALL	CH_WR
-;
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$14			; CHECK RESULT
-	JP	NZ,CHUSB_CMDERR		; HANDLE CMD ERROR
-;
-	XOR	A
-	RET
-;
-;
-;
-CHSD_STATUS:
-	; RETURN UNIT STATUS
-	LD	A,(IY+CHSD_STAT)	; GET STATUS OF SELECTED DEVICE
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-; RESET THE INTERFACE AND REDISCOVER MEDIA
-;
-CHSD_RESET:
-	;PRTS("\n\rRES SD:$")		; *DEBUG*
-;
-	; ACTIVATE SD MODE
-	LD	A,CH_CMD_MODE		; SET MODE COMMAND
-	CALL	CH_CMD			; SEND IT
-	LD	A,3			; SD MODE
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP			; SMALL WAIT
-	CALL	CH_RD			; GET RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CALL	CH_NAP			; SMALL WAIT
-;
-	LD	A,CH_MODE_SD		; WE ARE NOW IN SD MODE
-	LD	(CH_MODE),A		; SAVE IT
-;
-	CALL	CHSD_DSKMNT		; MOUNT DISK
-	RET	NZ
-;
-	; OPEN DISK IMAGE FILE
-	LD	DE,CHSD_FNAME
-	CALL	CHSD_FOPEN
-	RET	NZ
-;
-	; GET FILESIZE
-	CALL	CHSD_FILESIZE
-	RET	NZ
-;
-	; SET STATUS AND RETURN
-	XOR	A			; CLEAR STATUS
-	LD	(IY+CHSD_STAT),A	; RECORD STATUS
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-;
-;
-CHSD_DEVICE:
-	LD	D,DIODEV_CHSD		; D := DEVICE TYPE
-	LD	E,(IY+CH_DEV)		; E := PHYSICAL DEVICE NUMBER
-	LD	C,%00110010		; SD HARD DISK ATTRIBUTES
-	LD	H,(IY+CH_TYPE)		; H := MODE
-	LD	L,(IY+CH_IOBASE)	; L := BASE I/O ADDRESS
-	XOR	A			; SIGNAL SUCCESS
-	RET
-;
-; CHSD_GETMED
-;
-CHSD_MEDIA:
-	LD	A,E			; GET FLAGS
-	OR	A			; SET FLAGS
-	JR	Z,CHSD_MEDIA1		; JUST REPORT CURRENT STATUS AND MEDIA
-	CALL	CHSD_RESET		; RESET CHSD INTERFACE
-;
-CHSD_MEDIA1:
-	LD	A,(IY+CHSD_STAT)	; GET STATUS
-	OR	A			; SET FLAGS
-	LD	D,0			; NO MEDIA CHANGE DETECTED
-	LD	E,MID_HD		; ASSUME WE ARE OK
-	RET	Z			; RETURN IF GOOD INIT
-	LD	E,MID_NONE		; SIGNAL NO MEDIA
-	LD	A,ERR_NOMEDIA		; NO MEDIA ERROR
-	OR	A			; SET FLAGS
-	RET				; AND RETURN
-;
-;
-;
-CHSD_SEEK:
-	BIT	7,D			; CHECK FOR LBA FLAG
-	CALL	Z,HB_CHS2LBA		; CLEAR MEANS CHS, CONVERT TO LBA
-	RES	7,D			; CLEAR FLAG REGARDLESS (DOES NO HARM IF ALREADY LBA)
-	LD	(IY+CHSD_LBA+0),L	; SAVE NEW LBA
-	LD	(IY+CHSD_LBA+1),H	; ...
-	LD	(IY+CHSD_LBA+2),E	; ...
-	LD	(IY+CHSD_LBA+3),D	; ...
-	XOR	A			; SIGNAL SUCCESS
-	RET				; AND RETURN
-;
-;
-;
-CHSD_CAP:
-	LD	A,(IY+CHSD_STAT)	; GET STATUS
-	PUSH	AF			; SAVE IT
-	LD	A,CHSD_MEDCAP		; OFFSET TO CAPACITY FIELD
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	CALL	LD32			; GET THE CURRENT CAPACITY INTO DE:HL
-	LD	BC,512			; 512 BYTES PER BLOCK
-	POP	AF			; RECOVER STATUS
-	OR	A			; SET FLAGS
-	RET
-;
-;
-;
-CHSD_GEOM:
-	; FOR LBA, WE SIMULATE CHS ACCESS USING 16 HEADS AND 16 SECTORS
-	; RETURN HS:CC -> DE:HL, SET HIGH BIT OF D TO INDICATE LBA CAPABLE
-	CALL	CHSD_CAP		; GET TOTAL BLOCKS IN DE:HL, BLOCK SIZE TO BC
-	LD	L,H			; DIVIDE BY 256 FOR # TRACKS
-	LD	H,E			; ... HIGH BYTE DISCARDED, RESULT IN HL
-	LD	D,16 | $80		; HEADS / CYL = 16, SET LBA CAPABILITY BIT
-	LD	E,16			; SECTORS / TRACK = 16
-	RET				; DONE, A STILL HAS CHSD_CAP STATUS
-;
-; CH37X HELPER ROUTINES
-;
-;
-; PERFORM DISK MOUNT
-;
-CHSD_DSKMNT:
-	;PRTS("\n\rMOUNT:$")		; *DEBUG*
-	LD	A,CH_CMD_DSKMNT		; DISK QUERY
-	CALL	CH_CMD			; DO IT
-	CALL	CH_POLL			; WAIT FOR RESPONSE
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$82			; NO DISK?
-	JP	Z,CHSD_NOMEDIA		; HANDLE NO MEDIA ERROR
-	CP	$14			; SUCCESS?
-	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
-;
-#IF FALSE
-	CALL	CH_CMD_RD		; SEND READ COMMAND
-	CALL	CH_RD			; GET LENGTH
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	LD	B,A			; LOOP COUNTER
-	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
-CHSD_DSKMNT1:
-	CALL	CH_RD			; GET A BYTE
-	LD	(HL),A			; SAVE IT
-	INC	HL			; BUMP BUF PTR
-	DJNZ	CHSD_DSKMNT1		; LOOP FOR ALL DATA
-;
-	;LD	DE,HB_WRKBUF		; *DEBUG*
-	;CALL	DUMP_BUFFER		; *DEBUG*
-;
-	CALL	CHSD_PRTPREFIX		; PRINT DEVICE PREFIX
-	LD	HL,HB_WRKBUF + 8
-	LD	B,28
-CHSD_DSKMNT2:
-	LD	A,(HL)
-	INC	HL
-	CALL	COUT
-	DJNZ	CHSD_DSKMNT2
-#ENDIF
-;
-	XOR	A
-	RET
-;
-; SET FILE NAME
-;
-CHSD_SETFNAME:
-	;PRTS("\n\rSETFNAME:$")		; *DEBUG*
-	LD	A,CH_CMD_SET_FN		; SET FILE NAME COMMAND
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_NAP
-	;CALL	DELAY			; MAY NOT BE NEEDED
-	;CALL	PC_SPACE		; *DEBUG*
-CHSD_SETFNAME1:
-	;CALL	DELAY
-	LD	A,(DE)			; GET NEXT BYTE
-	INC	DE			; BUMP POINTER
-	CALL	CH_WR			; SEND IT
-	;CALL	COUT			; *DEBUG*
-	OR	A			; CHECK FOR NUL (EOS)
-	RET	Z			; IF NUL, DONE
-	JR	CHSD_SETFNAME1		; SEND MORE CHARACTERS
-;
-; OPEN FILE
-;
-CHSD_FOPEN:
-	CALL	CHSD_SETFNAME
-	;PRTS("\n\rFOPEN:$")		; *DEBUG*
-	LD	A,CH_CMD_FOPEN		; FILE OPEN  COMMAND
-	CALL	CH_CMD			; SEND IT
-	CALL	CH_POLL			; WAIT FOR RESULT
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEXBYTE		; *DEBUG*
-	CP	$42			; MISSING FILE?
-	JP	Z,CHSD_NOFILE		; HANDLE ERROR
-	CP	$14			; SUCCESS?
-	JP	NZ,CHSD_IOERR		; HANDLE ERROR
-	RET				; RETURN WITH ZF SET APPROPRIATELY
-;
-; GET FILE SIZE
-;
-CHSD_FILESIZE:
-	;PRTS("\n\rFSIZE:$")
-	LD	A,CH_CMD_FILESIZE	; FILE SIZE COMMAND
-	CALL	CH_CMD			; SEND IT
-	LD	A,$68			; REQUIRED CMD PARAMETER
-	CALL	CH_WR			; SEND IT
-	CALL	CH_NAP
-	LD	A,CHSD_MEDCAP		; MEDIA CAPACITY OFFSET
-	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
-	PUSH	HL			; SAVE ADDRESS
-	CALL	CH_RD
-	LD	L,A
-	CALL	CH_RD
-	LD	H,A
-	CALL	CH_RD
-	LD	E,A
-	CALL	CH_RD
-	LD	D,A
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEX32		; *DEBUG*
-	LD	B,9			; ROTATE 9 BITS FOR DIV 512
-CHSD_FILESIZE1:
-	SRL	D
-	RR	E
-	RR	H
-	RR	L
-	DJNZ	CHSD_FILESIZE1		; LOOP TILL DONE
-	POP	BC			; RECOVER ADDRESS TO BC
-	;CALL	PC_SPACE		; *DEBUG*
-	;CALL	PRTHEX32		; *DEBUG*
-	CALL	ST32			; STORE IT
-	XOR	A			; SIGNAL SUCCESS
-	RET				; AND DONE
-;
-; ERROR HANDLERS
-;
-;
-CHSD_NOFILE:
-	LD	A,CHSD_STNOFILE
-	JR	CHSD_ERR
-;
-CHSD_NOMEDIA:
-	LD	A,CHSD_STNOMEDIA
-	JR	CHSD_ERR
-;
-CHSD_CMDERR:
-	LD	A,CHSD_STCMDERR
-	JR	CHSD_ERR
-;
-CHSD_IOERR:
-	LD	A,CHSD_STIOERR
-	JR	CHSD_ERR
-;
-CHSD_TO:
-	LD	A,CHSD_STTO
-	JR	CHSD_ERR
-;
-CHSD_NOTSUP:
-	LD	A,CHSD_STNOTSUP
-	JR	CHSD_ERR
-;
-CHSD_ERR:
-	LD	(IY+CHSD_STAT),A	; SAVE NEW STATUS
-;
-CHSD_ERR2:
-#IF (CHSDTRACE >= 2)
-	CALL	CHSD_PRTSTAT
-#ENDIF
-	OR	A			; SET FLAGS
-	RET
-;
-;
-;
-CHSD_PRTERR:
-	RET	Z			; DONE IF NO ERRORS
-	; FALL THRU TO CHSD_PRTSTAT
-;
-; PRINT FULL DEVICE STATUS LINE
-;
-CHSD_PRTSTAT:
-	PUSH	AF
-	PUSH	DE
-	PUSH	HL
-	LD	A,(IY+CHSD_STAT)
-	CALL	CHSD_PRTPREFIX		; PRINT UNIT PREFIX
-	CALL	PC_SPACE		; FORMATTING
-	CALL	CHSD_PRTSTATSTR
-	POP	HL
-	POP	DE
-	POP	AF
-	RET
-;
-; PRINT STATUS STRING
-;
-CHSD_PRTSTATSTR:
-	PUSH	AF
-	PUSH	DE
-	PUSH	HL
-	LD	A,(IY+CHSD_STAT)
-	NEG
-	LD	HL,CHSD_STR_ST_MAP
-	ADD	A,A
-	CALL	ADDHLA
-	LD	E,(HL)
-	INC	HL
-	LD	D,(HL)
-	CALL	WRITESTR
-	POP	HL
-	POP	DE
-	POP	AF
-	RET
-;
-; PRINT DIAGNONSTIC PREFIX
-;
-CHSD_PRTPREFIX:
-	PUSH	AF
-	CALL	NEWLINE
-	PRTS("CHSD$")
-	LD	A,(IY+CH_DEV)		; GET CURRENT DEVICE NUM
-	CALL	PRTDECB
-	CALL	PC_COLON
-	POP	AF
-	RET
-;
-; DATA STORAGE
-;
-CHSD_DEVNUM	.DB	0		; TEMP DEVICE NUM USED DURING INIT
-CHSD_DSKBUF	.DW	0
-;
-CHSD_FNAME	.DB	"/", CHSD_IMGFILE, 0
-;
-CHSD_STR_ST_MAP:
-	.DW		CHSD_STR_STOK
-	.DW		CHSD_STR_STNOMEDIA
-	.DW		CHSD_STR_STCMDERR
-	.DW		CHSD_STR_STIOERR
-	.DW		CHSD_STR_STTO
-	.DW		CHSD_STR_STNOTSUP
-	.DW		CHSD_STR_STNOFILE
-;
-CHSD_STR_STOK		.TEXT	"OK$"
-CHSD_STR_STNOMEDIA	.TEXT	"NO MEDIA$"
-CHSD_STR_STCMDERR	.TEXT	"COMMAND ERROR$"
-CHSD_STR_STIOERR	.TEXT	"IO ERROR$"
-CHSD_STR_STTO		.TEXT	"TIMEOUT$"
-CHSD_STR_STNOTSUP	.TEXT	"NOT SUPPORTED$"
-CHSD_STR_STNOFILE	.TEXT	"MISSING "
-			.TEXT	CHSD_IMGFILE
-			.TEXT	" FILE$"
-CHSD_STR_STUNK		.TEXT	"UNKNOWN ERROR$"
diff --git a/Source/HBIOS/chsd.asm b/Source/HBIOS/chsd.asm
new file mode 100644
index 00000000..a5789c9a
--- /dev/null
+++ b/Source/HBIOS/chsd.asm
@@ -0,0 +1,685 @@
+;
+;==================================================================================================
+; CH376 SD CARD SUB-DRIVER
+;==================================================================================================
+;
+; Thanks and credit to Alan Cox.  Much of this driver is based on
+; his code in FUZIX (https://github.com/EtchedPixels/FUZIX).
+;
+; This file contains the SD Card specific support for the CH37x
+; driver.  This file is included by the core driver file (ch.asm) as
+; needed.  Note that only the CH376 actually supports SD Card access.
+;
+; The SD Card support is implemented using the CH376 file-level
+; support.  It is *not* possible to access SD Cards using raw
+; sector I/O.
+;
+; TODO:
+;  - Implement auto-recovery on error status?
+;
+#DEFINE	CHSD_IMGFILE "DISK.IMG"
+;
+CHSD_FASTIO	.EQU	TRUE		; USE INIR/OTIR?
+;
+; CHUSB DEVICE STATUS
+;
+CHSD_STOK	.EQU	0
+CHSD_STNOMEDIA	.EQU	-1
+CHSD_STCMDERR	.EQU	-2
+CHSD_STIOERR	.EQU	-3
+CHSD_STTO	.EQU	-4
+CHSD_STNOTSUP	.EQU	-5
+CHSD_STNOFILE	.EQU	-6
+;
+; CHSD DEVICE CONFIGURATION
+;
+CHSD_CFGSIZ	.EQU	14		; SIZE OF USB CFG TBL ENTRIES
+;
+; CONFIG ENTRY DATA OFFSETS
+;
+; THE LOCATION OF CHSD_MODE IS SHARED BY ALL SUB-DRIVERS AND THE
+; CH_SETMODE FUNCTION IN THE MAIN DRIVER (CH.ASM).  IF YOU CHANGE
+; IT, YOU MUST SYNC UP THE MAIN DRIVER AND ALL SUB-DRIVERS!
+;
+; FIRST 3 BYTES SAME AS CH CONFIG
+CHSD_STAT	.EQU	3		; LAST STATUS (BYTE)
+CHSD_MEDCAP	.EQU	4		; MEDIA CAPACITY (DWORD)
+CHSD_LBA	.EQU	8		; CURRENT LBA (DWORD)
+CHSD_MODE	.EQU	12		; PTR TO MODE BYTE (WORD)
+;
+CHSD_CFGTBL:
+;
+#IF (CHCNT >= 1)
+CHSD_CFG0:
+	.DB	0			; DEV NUM, FILLED DYNAMICALLY
+	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
+	.DB	CH0BASE			; IO BASE ADDRESS
+	.DB	0			; DEVICE STATUS
+	.DW	0,0			; DEVICE CAPACITY
+	.DW	0,0			; CURRENT LBA
+	.DW	CH0_MODE		; POINTER TO MODE BYTE
+;
+  #IF (CH0SDENABLE)
+	.ECHO	"CHSD: IO="
+	.ECHO	CH0BASE
+	.ECHO	"\n"
+  #ENDIF
+#ENDIF
+;
+#IF (CHCNT >= 2)
+CHSD_CFG1:
+	.DB	0			; DEV NUM
+	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
+	.DB	CH1BASE			; IO BASE ADDRESS
+	.DB	0			; DEVICE STATUS
+	.DW	0,0			; DEVICE CAPACITY
+	.DW	0,0			; CURRENT LBA
+	.DW	CH1_MODE		; POINTER TO MODE BYTE
+;
+  #IF (CH1SDENABLE)
+	.ECHO	"CHSD: IO="
+	.ECHO	CH1BASE
+	.ECHO	"\n"
+  #ENDIF
+#ENDIF
+;
+#IF ($ - CHSD_CFGTBL) != (CHCNT * CHSD_CFGSIZ)
+	.ECHO	"*** INVALID CHSD CONFIG TABLE ***\n"
+#ENDIF
+;
+	.DB	$FF			; END OF TABLE MARKER
+;
+;
+;
+CHSD_INIT:
+	LD	A,(IY+CH_TYPE)		; GET DEVICE TYPE
+	PUSH	HL			; COPY INCOMING HL
+	POP	IY			; ... TO IY
+	LD	(IY+CH_TYPE),A		; SAVE DEVICE TYPE
+;
+	; UPDATE DRIVER RELATIVE UNIT NUMBER IN CONFIG TABLE
+	LD	A,(CHSD_DEVNUM)		; GET NEXT UNIT NUM TO ASSIGN
+	LD	(IY+CH_DEV),A		; UPDATE IT
+	INC	A			; BUMP TO NEXT UNIT NUM TO ASSIGN
+	LD	(CHSD_DEVNUM),A		; SAVE IT
+;
+	; ADD UNIT TO GLOBAL DISK UNIT TABLE
+	LD	BC,CHSD_FNTBL		; BC := FUNC TABLE ADR
+	PUSH	IY			; CFG ENTRY POINTER
+	POP	DE			; COPY TO DE
+	CALL	DIO_ADDENT		; ADD ENTRY TO GLOBAL DISK DEV TABLE
+;
+	CALL	CHSD_RESET		; RESET & DISCOVER MEDIA
+#IF (CHSDTRACE <= 1)
+	CALL	NZ,CHSD_PRTSTAT
+#ENDIF
+	RET	NZ			; ABORT ON FAILURE
+;
+	; START PRINTING DEVICE INFO
+	CALL	CHSD_PRTPREFIX		; PRINT DEVICE PREFIX
+;
+	; PRINT STORAGE CAPACITY (BLOCK COUNT)
+	PRTS(" BLOCKS=0x$")		; PRINT FIELD LABEL
+	LD	A,CHSD_MEDCAP		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	LD32			; GET THE CAPACITY VALUE
+	CALL	PRTHEX32		; PRINT HEX VALUE
+;
+	; PRINT STORAGE SIZE IN MB
+	PRTS(" SIZE=$")			; PRINT FIELD LABEL
+	LD	B,11			; 11 BIT SHIFT TO CONVERT BLOCKS --> MB
+	CALL	SRL32			; RIGHT SHIFT
+	CALL	PRTDEC32		; PRINT DWORD IN DECIMAL
+	PRTS("MB$")			; PRINT SUFFIX
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; DRIVER FUNCTION TABLE
+;
+CHSD_FNTBL:
+	.DW	CHSD_STATUS
+	.DW	CHSD_RESET
+	.DW	CHSD_SEEK
+	.DW	CHSD_READ
+	.DW	CHSD_WRITE
+	.DW	CHSD_VERIFY
+	.DW	CHSD_FORMAT
+	.DW	CHSD_DEVICE
+	.DW	CHSD_MEDIA
+	.DW	CHSD_DEFMED
+	.DW	CHSD_CAP
+	.DW	CHSD_GEOM
+#IF (($ - CHSD_FNTBL) != (DIO_FNCNT * 2))
+	.ECHO	"*** INVALID CHSD FUNCTION TABLE ***\n"
+#ENDIF
+;
+CHSD_VERIFY:
+CHSD_FORMAT:
+CHSD_DEFMED:
+	SYSCHKERR(ERR_NOTIMPL)		; NOT IMPLEMENTED
+	RET
+;
+;
+;
+CHSD_READ:
+	LD	A,CH_MODE_SD		; REQUEST SD MODE
+	CALL	CH_SETMODE		; DO IT
+	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
+;
+	CALL	HB_DSKREAD		; HOOK HBIOS DISK READ SUPERVISOR
+	LD	(CHSD_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
+	CALL	CHSD_RWSTART		; SET LBA OFFSET
+	RET	NZ
+;
+	;PRTS("\n\rREAD:$")		; *DEBUG*
+	LD	A,CH_CMD_BYTERD		; BYTE READ
+	CALL	CH_CMD			; SEND COMMAND
+	CALL	CH_NAP
+	LD	A,0			; LSB
+	CALL	CH_WR			; SEND IT
+	LD	A,2			; MSB
+	CALL	CH_WR			; SEND IT
+	CALL	CH_POLL			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$1D			; DATA READY TO READ?
+	JP	NZ,CHSD_IOERR		; HANDLE I/O ERROR
+;
+	LD	HL,(CHSD_DSKBUF)
+CHSD_READ1:
+	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
+	CALL	CH_RD			; GET DATA LENGTH
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+#IF (CHSD_FASTIO)
+	LD	B,A			; BYTE COUNT TO READ
+	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	INIR				; DO IT FAST
+#ELSE
+	LD	B,A			; SAVE IT
+CHSD_READ2:
+	CALL	CH_RD			; GET DATA BYTE
+	LD	(HL),A			; SAVE IN BUFFER
+	INC	HL			; INC BUF PTR
+	DJNZ	CHSD_READ2		; LOOP TILL DONE W/ ALL BYTES
+#ENDIF
+;
+	LD	A,CH_CMD_BYTERDGO	; BYTE READ GO COMMAND
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_NAP
+	CALL	CH_POLL			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$1D			; MORE?
+	JR	Z,CHSD_READ1		; IF SO, GET MORE
+	CP	$14			; GOOD FINISH?
+	JP	NZ,CHSD_IOERR		; HANDLE ERROR
+;
+	; INCREMENT LBA
+	PUSH	HL			; SAVE HL
+	LD	A,CHSD_LBA		; LBA OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	INC32HL			; INCREMENT THE VALUE
+	POP	HL			; RESTORE HL
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+;
+;
+CHSD_WRITE:
+	LD	A,CH_MODE_SD		; REQUEST SD MODE
+	CALL	CH_SETMODE		; DO IT
+	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
+;
+	CALL	HB_DSKWRITE		; HOOK HBIOS DISK WRITE SUPERVISOR
+	LD	(CHSD_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
+	CALL	CHSD_RWSTART		; SET LBA OFFSET'
+	RET	NZ
+;
+	;PRTS("\n\rWRITE:$")		; *DEBUG*
+	LD	A,CH_CMD_BYTEWR		; BYTE WRITE
+	CALL	CH_CMD			; SEND COMMAND
+	LD	A,0			; LSB
+	CALL	CH_WR			; SEND IT
+	LD	A,2			; MSB
+	CALL	CH_WR			; SEND IT
+	CALL	CH_POLL			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$1E			; DATA READY TO GO?
+	JP	NZ,CHSD_IOERR		; HANDLE I/O ERROR
+;
+	LD	HL,(CHSD_DSKBUF)
+CHSD_WRITE1:
+	LD	A,CH_CMD_WRREQDAT	; WRITE REQUESTED DATA CMD
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_RD			; GET DATA LENGTH
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+#IF (CHSD_FASTIO)
+	LD	B,A			; BYTE COUNT TO WRITE
+	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	OTIR				; DO IT FAST
+#ELSE
+	LD	B,A			; SAVE IT
+CHSD_WRITE2:
+	CALL	CH_WR			; WRITE DATA BYTE
+	LD	(HL),A			; SAVE IN BUFFER
+	INC	HL			; INC BUF PTR
+	DJNZ	CHSD_WRITE2		; LOOP TILL DONE W/ ALL BYTES
+#ENDIF
+;
+	LD	A,CH_CMD_BYTEWRGO	; BYTE WRITE GO COMMAND
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_NAP
+	CALL	CH_POLL			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$1E			; MORE?
+	JR	Z,CHSD_WRITE1		; IF SO, SEND MORE
+	CP	$14			; GOOD FINISH?
+	JP	NZ,CHSD_IOERR		; HANDLE ERROR
+;
+	; INCREMENT LBA
+	PUSH	HL			; SAVE HL
+	LD	A,CHSD_LBA		; LBA OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	INC32HL			; INCREMENT THE VALUE
+	POP	HL			; RESTORE HL
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; SEEK TO CURRENT LBA
+;
+CHSD_RWSTART:
+	;PRTS("\n\rRWST:$")		; *DEBUG*
+	LD	A,CH_CMD_BYTE_LOC	; BYTE LOCATE COMMAND (SEEK)
+	CALL	CH_CMD			; SEND IT
+;
+	; GET CURRENT LBA OFFSET
+	LD	A,CHSD_LBA		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	LD32			; OFFSET = DE:HL
+;
+	; CONVERT OFFSET FROM LBA TO BYTE
+	LD	B,9
+CHSD_RWSTART1:
+	SLA	L
+	RL	H
+	RL	E
+	RL	D
+	DJNZ	CHSD_RWSTART1
+	;CALL	PRTHEX32		; *DEBUG*
+;
+	; SEND THE BYTE OFFSET (LSB FIRST)
+	LD	A,L
+	CALL	CH_WR
+	LD	A,H
+	CALL	CH_WR
+	LD	A,E
+	CALL	CH_WR
+	LD	A,D
+	CALL	CH_WR
+;
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; CHECK RESULT
+	JP	NZ,CHSD_CMDERR		; HANDLE CMD ERROR
+;
+	XOR	A
+	RET
+;
+;
+;
+CHSD_STATUS:
+	; RETURN UNIT STATUS
+	LD	A,(IY+CHSD_STAT)	; GET STATUS OF SELECTED DEVICE
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+; RESET THE INTERFACE AND REDISCOVER MEDIA
+;
+CHSD_RESET:
+	;PRTS("\n\rRES SD:$")		; *DEBUG*
+;
+	; ACTIVATE SD MODE
+	LD	A,CH_CMD_MODE		; SET MODE COMMAND
+	CALL	CH_CMD			; SEND IT
+	LD	A,3			; SD MODE
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP			; SMALL WAIT
+	CALL	CH_RD			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CALL	CH_NAP			; SMALL WAIT
+;
+	LD	A,CH_MODE_SD		; WE ARE NOW IN SD MODE
+	LD	L,(IY+CHSD_MODE+0)	; GET MODE PTR (LSB)
+	LD	H,(IY+CHSD_MODE+1)	; GET MODE PTR (MSB)
+	LD	(HL),A			; SAVE IT
+;
+	CALL	CHSD_DSKMNT		; MOUNT DISK
+	RET	NZ
+;
+	; OPEN DISK IMAGE FILE
+	LD	DE,CHSD_FNAME
+	CALL	CHSD_FOPEN
+	RET	NZ
+;
+	; GET FILESIZE
+	CALL	CHSD_FILESIZE
+	RET	NZ
+;
+	; SET STATUS AND RETURN
+	XOR	A			; CLEAR STATUS
+	LD	(IY+CHSD_STAT),A	; RECORD STATUS
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+;
+;
+CHSD_DEVICE:
+	LD	D,DIODEV_CHSD		; D := DEVICE TYPE
+	LD	E,(IY+CH_DEV)		; E := PHYSICAL DEVICE NUMBER
+	LD	C,%00110010		; SD HARD DISK ATTRIBUTES
+	LD	H,(IY+CH_TYPE)		; H := MODE
+	LD	L,(IY+CH_IOBASE)	; L := BASE I/O ADDRESS
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; CHSD_GETMED
+;
+CHSD_MEDIA:
+	LD	A,E			; GET FLAGS
+	OR	A			; SET FLAGS
+	JR	Z,CHSD_MEDIA1		; JUST REPORT CURRENT STATUS AND MEDIA
+	CALL	CHSD_RESET		; RESET CHSD INTERFACE
+;
+CHSD_MEDIA1:
+	LD	A,(IY+CHSD_STAT)	; GET STATUS
+	OR	A			; SET FLAGS
+	LD	D,0			; NO MEDIA CHANGE DETECTED
+	LD	E,MID_HD		; ASSUME WE ARE OK
+	RET	Z			; RETURN IF GOOD INIT
+	LD	E,MID_NONE		; SIGNAL NO MEDIA
+	LD	A,ERR_NOMEDIA		; NO MEDIA ERROR
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+;
+;
+CHSD_SEEK:
+	BIT	7,D			; CHECK FOR LBA FLAG
+	CALL	Z,HB_CHS2LBA		; CLEAR MEANS CHS, CONVERT TO LBA
+	RES	7,D			; CLEAR FLAG REGARDLESS (DOES NO HARM IF ALREADY LBA)
+	LD	(IY+CHSD_LBA+0),L	; SAVE NEW LBA
+	LD	(IY+CHSD_LBA+1),H	; ...
+	LD	(IY+CHSD_LBA+2),E	; ...
+	LD	(IY+CHSD_LBA+3),D	; ...
+	XOR	A			; SIGNAL SUCCESS
+	RET				; AND RETURN
+;
+;
+;
+CHSD_CAP:
+	LD	A,(IY+CHSD_STAT)	; GET STATUS
+	PUSH	AF			; SAVE IT
+	LD	A,CHSD_MEDCAP		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	LD32			; GET THE CURRENT CAPACITY INTO DE:HL
+	LD	BC,512			; 512 BYTES PER BLOCK
+	POP	AF			; RECOVER STATUS
+	OR	A			; SET FLAGS
+	RET
+;
+;
+;
+CHSD_GEOM:
+	; FOR LBA, WE SIMULATE CHS ACCESS USING 16 HEADS AND 16 SECTORS
+	; RETURN HS:CC -> DE:HL, SET HIGH BIT OF D TO INDICATE LBA CAPABLE
+	CALL	CHSD_CAP		; GET TOTAL BLOCKS IN DE:HL, BLOCK SIZE TO BC
+	LD	L,H			; DIVIDE BY 256 FOR # TRACKS
+	LD	H,E			; ... HIGH BYTE DISCARDED, RESULT IN HL
+	LD	D,16 | $80		; HEADS / CYL = 16, SET LBA CAPABILITY BIT
+	LD	E,16			; SECTORS / TRACK = 16
+	RET				; DONE, A STILL HAS CHSD_CAP STATUS
+;
+; CH37X HELPER ROUTINES
+;
+;
+; PERFORM DISK MOUNT
+;
+CHSD_DSKMNT:
+	;PRTS("\n\rMOUNT:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKMNT		; DISK QUERY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$82			; NO DISK?
+	JP	Z,CHSD_NOMEDIA		; HANDLE NO MEDIA ERROR
+	CP	$14			; SUCCESS?
+	JP	NZ,CHSD_CMDERR		; HANDLE ERROR
+;
+#IF FALSE
+	CALL	CH_CMD_RD		; SEND READ COMMAND
+	CALL	CH_RD			; GET LENGTH
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	LD	B,A			; LOOP COUNTER
+	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
+CHSD_DSKMNT1:
+	CALL	CH_RD			; GET A BYTE
+	LD	(HL),A			; SAVE IT
+	INC	HL			; BUMP BUF PTR
+	DJNZ	CHSD_DSKMNT1		; LOOP FOR ALL DATA
+;
+	;LD	DE,HB_WRKBUF		; *DEBUG*
+	;CALL	DUMP_BUFFER		; *DEBUG*
+;
+	CALL	CHSD_PRTPREFIX		; PRINT DEVICE PREFIX
+	LD	HL,HB_WRKBUF + 8
+	LD	B,28
+CHSD_DSKMNT2:
+	LD	A,(HL)
+	INC	HL
+	CALL	COUT
+	DJNZ	CHSD_DSKMNT2
+#ENDIF
+;
+	XOR	A
+	RET
+;
+; SET FILE NAME
+;
+CHSD_SETFNAME:
+	;PRTS("\n\rSETFNAME:$")		; *DEBUG*
+	LD	A,CH_CMD_SET_FN		; SET FILE NAME COMMAND
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_NAP
+	;CALL	DELAY			; MAY NOT BE NEEDED
+	;CALL	PC_SPACE		; *DEBUG*
+CHSD_SETFNAME1:
+	;CALL	DELAY
+	LD	A,(DE)			; GET NEXT BYTE
+	INC	DE			; BUMP POINTER
+	CALL	CH_WR			; SEND IT
+	;CALL	COUT			; *DEBUG*
+	OR	A			; CHECK FOR NUL (EOS)
+	RET	Z			; IF NUL, DONE
+	JR	CHSD_SETFNAME1		; SEND MORE CHARACTERS
+;
+; OPEN FILE
+;
+CHSD_FOPEN:
+	CALL	CHSD_SETFNAME
+	;PRTS("\n\rFOPEN:$")		; *DEBUG*
+	LD	A,CH_CMD_FOPEN		; FILE OPEN  COMMAND
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_POLL			; WAIT FOR RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$42			; MISSING FILE?
+	JP	Z,CHSD_NOFILE		; HANDLE ERROR
+	CP	$14			; SUCCESS?
+	JP	NZ,CHSD_IOERR		; HANDLE ERROR
+	RET				; RETURN WITH ZF SET APPROPRIATELY
+;
+; GET FILE SIZE
+;
+CHSD_FILESIZE:
+	;PRTS("\n\rFSIZE:$")
+	LD	A,CH_CMD_FILESIZE	; FILE SIZE COMMAND
+	CALL	CH_CMD			; SEND IT
+	LD	A,$68			; REQUIRED CMD PARAMETER
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP
+	LD	A,CHSD_MEDCAP		; MEDIA CAPACITY OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	PUSH	HL			; SAVE ADDRESS
+	CALL	CH_RD
+	LD	L,A
+	CALL	CH_RD
+	LD	H,A
+	CALL	CH_RD
+	LD	E,A
+	CALL	CH_RD
+	LD	D,A
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEX32		; *DEBUG*
+	LD	B,9			; ROTATE 9 BITS FOR DIV 512
+CHSD_FILESIZE1:
+	SRL	D
+	RR	E
+	RR	H
+	RR	L
+	DJNZ	CHSD_FILESIZE1		; LOOP TILL DONE
+	POP	BC			; RECOVER ADDRESS TO BC
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEX32		; *DEBUG*
+	CALL	ST32			; STORE IT
+	XOR	A			; SIGNAL SUCCESS
+	RET				; AND DONE
+;
+; ERROR HANDLERS
+;
+;
+CHSD_NOFILE:
+	LD	A,CHSD_STNOFILE
+	JR	CHSD_ERR
+;
+CHSD_NOMEDIA:
+	LD	A,CHSD_STNOMEDIA
+	JR	CHSD_ERR
+;
+CHSD_CMDERR:
+	LD	A,CHSD_STCMDERR
+	JR	CHSD_ERR
+;
+CHSD_IOERR:
+	LD	A,CHSD_STIOERR
+	JR	CHSD_ERR
+;
+CHSD_TO:
+	LD	A,CHSD_STTO
+	JR	CHSD_ERR
+;
+CHSD_NOTSUP:
+	LD	A,CHSD_STNOTSUP
+	JR	CHSD_ERR
+;
+CHSD_ERR:
+	LD	(IY+CHSD_STAT),A	; SAVE NEW STATUS
+;
+CHSD_ERR2:
+#IF (CHSDTRACE >= 2)
+	CALL	CHSD_PRTSTAT
+#ENDIF
+	OR	A			; SET FLAGS
+	RET
+;
+;
+;
+CHSD_PRTERR:
+	RET	Z			; DONE IF NO ERRORS
+	; FALL THRU TO CHSD_PRTSTAT
+;
+; PRINT FULL DEVICE STATUS LINE
+;
+CHSD_PRTSTAT:
+	PUSH	AF
+	PUSH	DE
+	PUSH	HL
+	LD	A,(IY+CHSD_STAT)
+	CALL	CHSD_PRTPREFIX		; PRINT UNIT PREFIX
+	CALL	PC_SPACE		; FORMATTING
+	CALL	CHSD_PRTSTATSTR
+	POP	HL
+	POP	DE
+	POP	AF
+	RET
+;
+; PRINT STATUS STRING
+;
+CHSD_PRTSTATSTR:
+	PUSH	AF
+	PUSH	DE
+	PUSH	HL
+	LD	A,(IY+CHSD_STAT)
+	NEG
+	LD	HL,CHSD_STR_ST_MAP
+	ADD	A,A
+	CALL	ADDHLA
+	LD	E,(HL)
+	INC	HL
+	LD	D,(HL)
+	CALL	WRITESTR
+	POP	HL
+	POP	DE
+	POP	AF
+	RET
+;
+; PRINT DIAGNONSTIC PREFIX
+;
+CHSD_PRTPREFIX:
+	PUSH	AF
+	CALL	NEWLINE
+	PRTS("CHSD$")
+	LD	A,(IY+CH_DEV)		; GET CURRENT DEVICE NUM
+	CALL	PRTDECB
+	CALL	PC_COLON
+	POP	AF
+	RET
+;
+; DATA STORAGE
+;
+CHSD_DEVNUM	.DB	0		; TEMP DEVICE NUM USED DURING INIT
+CHSD_DSKBUF	.DW	0
+;
+CHSD_FNAME	.DB	"/", CHSD_IMGFILE, 0
+;
+CHSD_STR_ST_MAP:
+	.DW		CHSD_STR_STOK
+	.DW		CHSD_STR_STNOMEDIA
+	.DW		CHSD_STR_STCMDERR
+	.DW		CHSD_STR_STIOERR
+	.DW		CHSD_STR_STTO
+	.DW		CHSD_STR_STNOTSUP
+	.DW		CHSD_STR_STNOFILE
+;
+CHSD_STR_STOK		.TEXT	"OK$"
+CHSD_STR_STNOMEDIA	.TEXT	"NO MEDIA$"
+CHSD_STR_STCMDERR	.TEXT	"COMMAND ERROR$"
+CHSD_STR_STIOERR	.TEXT	"IO ERROR$"
+CHSD_STR_STTO		.TEXT	"TIMEOUT$"
+CHSD_STR_STNOTSUP	.TEXT	"NOT SUPPORTED$"
+CHSD_STR_STNOFILE	.TEXT	"MISSING "
+			.TEXT	CHSD_IMGFILE
+			.TEXT	" FILE$"
+CHSD_STR_STUNK		.TEXT	"UNKNOWN ERROR$"
diff --git a/Source/HBIOS/chusb.asm b/Source/HBIOS/chusb.asm
new file mode 100644
index 00000000..fd4c5d44
--- /dev/null
+++ b/Source/HBIOS/chusb.asm
@@ -0,0 +1,792 @@
+;
+;==================================================================================================
+; CH375/376 USB SUB-DRIVER
+;==================================================================================================
+;
+; Thanks and credit to Alan Cox.  Much of this driver is based on
+; his code in FUZIX (https://github.com/EtchedPixels/FUZIX).
+;
+; This file contains the USB Drive specific support for the CH37x
+; driver.  This file is included by the core driver file (ch.asm) as
+; needed.
+;
+; The USB support is implemented as pure raw sector I/O.  The CH376
+; file-level support is not utilized.
+;
+; NOTES:
+;  - There seem to be compatibility issues with older USB thumb drives.
+;    Such drives will complete DISK_INIT successfully, but then return
+;    an error attempting to do any I/O.  The error is $17 indicating
+;    the CH37x encountered an overflow during communication with the
+;    device.   I found that adding a DISK_MOUNT command (only possible
+;    on CH376) resolved the issue for some devices, so that has been
+;    added to the RESET routine when using CH376.
+;
+; TODO:
+;  - Implement auto-recovery on error status?
+;
+CHUSB_FASTIO	.EQU	TRUE		; USE INIR/OTIR?
+;
+; CHUSB DEVICE STATUS
+;
+CHUSB_STOK	.EQU	0
+CHUSB_STNOMEDIA	.EQU	-1
+CHUSB_STCMDERR	.EQU	-2
+CHUSB_STIOERR	.EQU	-3
+CHUSB_STTO	.EQU	-4
+CHUSB_STNOTSUP	.EQU	-5
+;
+; CHUSB DEVICE CONFIGURATION
+;
+CHUSB_CFGSIZ	.EQU	14		; SIZE OF USB CFG TBL ENTRIES
+;
+; CONFIG ENTRY DATA OFFSETS
+;
+; THE LOCATION OF CHSD_MODE IS SHARED BY ALL SUB-DRIVERS AND THE
+; CH_SETMODE FUNCTION IN THE MAIN DRIVER (CH.ASM).  IF YOU CHANGE
+; IT, YOU MUST SYNC UP THE MAIN DRIVER AND ALL SUB-DRIVERS!
+;
+; FIRST 3 BYTES SAME AS CH CONFIG
+CHUSB_STAT	.EQU	3		; LAST STATUS (BYTE)
+CHUSB_MEDCAP	.EQU	4		; MEDIA CAPACITY (DWORD)
+CHUSB_LBA	.EQU	8		; CURRENT LBA (DWORD)
+CHUSB_MODE	.EQU	12		; PTR TO MODE BYTE (WORD)
+;
+CHUSB_CFGTBL:
+;
+#IF (CHCNT >= 1)
+CHUSB_CFG0:
+	.DB	0			; DEV NUM, FILLED DYNAMICALLY
+	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
+	.DB	CH0BASE			; IO BASE ADDRESS
+	.DB	0			; DEVICE STATUS
+	.DW	0,0			; DEVICE CAPACITY
+	.DW	0,0			; CURRENT LBA
+	.DW	CH0_MODE		; POINTER TO MODE BYTE
+;
+  #IF (CH0USBENABLE)
+	.ECHO	"CHUSB: IO="
+	.ECHO	CH0BASE
+	.ECHO	"\n"
+  #ENDIF
+#ENDIF
+;
+#IF (CHCNT >= 2)
+CHUSB_CFG1:
+	.DB	0			; DEV NUM
+	.DB	CHTYP_NONE		; DEV TYPE, FILLED DYNCAMICALLY
+	.DB	CH1BASE			; IO BASE ADDRESS
+	.DB	0			; DEVICE STATUS
+	.DW	0,0			; DEVICE CAPACITY
+	.DW	0,0			; CURRENT LBA
+	.DW	CH1_MODE		; POINTER TO MODE BYTE
+;
+  #IF (CH1USBENABLE)
+	.ECHO	"CHUSB: IO="
+	.ECHO	CH1BASE
+	.ECHO	"\n"
+  #ENDIF
+#ENDIF
+;
+#IF ($ - CHUSB_CFGTBL) != (CHCNT * CHUSB_CFGSIZ)
+	.ECHO	"*** INVALID CHUSB CONFIG TABLE ***\n"
+#ENDIF
+;
+	.DB	$FF			; END OF TABLE MARKER
+;
+;
+;
+CHUSB_INIT:
+	LD	A,(IY+CH_TYPE)		; GET DEVICE TYPE
+	PUSH	HL			; COPY INCOMING HL
+	POP	IY			; ... TO IY
+	LD	(IY+CH_TYPE),A		; SAVE DEVICE TYPE
+;
+	; UPDATE DRIVER RELATIVE UNIT NUMBER IN CONFIG TABLE
+	LD	A,(CHUSB_DEVNUM)	; GET NEXT UNIT NUM TO ASSIGN
+	LD	(IY+CH_DEV),A		; UPDATE IT
+	INC	A			; BUMP TO NEXT UNIT NUM TO ASSIGN
+	LD	(CHUSB_DEVNUM),A	; SAVE IT
+;
+	; ADD UNIT TO GLOBAL DISK UNIT TABLE
+	LD	BC,CHUSB_FNTBL		; BC := FUNC TABLE ADR
+	PUSH	IY			; CFG ENTRY POINTER
+	POP	DE			; COPY TO DE
+	CALL	DIO_ADDENT		; ADD ENTRY TO GLOBAL DISK DEV TABLE
+;
+	CALL	CHUSB_RESET		; RESET & DISCOVER MEDIA
+#IF (CHUSBTRACE <= 1)
+	CALL	NZ,CHUSB_PRTSTAT
+#ENDIF
+	RET	NZ			; ABORT ON FAILURE
+;
+	; START PRINTING DEVICE INFO
+	CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
+;
+	; PRINT STORAGE CAPACITY (BLOCK COUNT)
+	PRTS(" BLOCKS=0x$")		; PRINT FIELD LABEL
+	LD	A,CHUSB_MEDCAP		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	LD32			; GET THE CAPACITY VALUE
+	CALL	PRTHEX32		; PRINT HEX VALUE
+;
+	; PRINT STORAGE SIZE IN MB
+	PRTS(" SIZE=$")			; PRINT FIELD LABEL
+	LD	B,11			; 11 BIT SHIFT TO CONVERT BLOCKS --> MB
+	CALL	SRL32			; RIGHT SHIFT
+	CALL	PRTDEC32		; PRINT DWORD IN DECIMAL
+	PRTS("MB$")			; PRINT SUFFIX
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; DRIVER FUNCTION TABLE
+;
+CHUSB_FNTBL:
+	.DW	CHUSB_STATUS
+	.DW	CHUSB_RESET
+	.DW	CHUSB_SEEK
+	.DW	CHUSB_READ
+	.DW	CHUSB_WRITE
+	.DW	CHUSB_VERIFY
+	.DW	CHUSB_FORMAT
+	.DW	CHUSB_DEVICE
+	.DW	CHUSB_MEDIA
+	.DW	CHUSB_DEFMED
+	.DW	CHUSB_CAP
+	.DW	CHUSB_GEOM
+#IF (($ - CHUSB_FNTBL) != (DIO_FNCNT * 2))
+	.ECHO	"*** INVALID CHUSB FUNCTION TABLE ***\n"
+#ENDIF
+;
+CHUSB_VERIFY:
+CHUSB_FORMAT:
+CHUSB_DEFMED:
+	SYSCHKERR(ERR_NOTIMPL)		; NOT IMPLEMENTED
+	RET
+;
+;
+;
+CHUSB_READ:
+	LD	A,CH_MODE_USB		; REQUEST USB MODE
+	CALL	CH_SETMODE		; DO IT
+	JP	NZ,CHUSB_CMDERR		; HANDLE ERROR
+;
+	CALL	HB_DSKREAD		; HOOK HBIOS DISK READ SUPERVISOR
+	LD	(CHUSB_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
+	LD	A,CH_CMD_DSKRD		; DISK READ COMMAND
+	CALL	CHUSB_RWSTART		; SEND CMD AND LBA
+;
+	; READ THE SECTOR IN 64 BYTE CHUNKS
+	LD	B,8			; 8 CHUNKS OF 64 FOR 512 BYTE SECTOR
+	LD	HL,(CHUSB_DSKBUF)	; GET DISK BUF ADR
+CHUSB_READ1:
+	CALL	CH_POLL			; WAIT FOR DATA READY
+	CP	$1D			; DATA READY TO READ?
+	;CALL	PC_LT			; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	JP	NZ,CHUSB_IOERR		; HANDLE IO ERROR
+	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
+	CALL	CH_RD			; READ DATA BLOCK LENGTH
+	CP	64			; AS EXPECTED?
+	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
+;
+#IF (CHUSB_FASTIO)
+	; READ 64 BYTE CHUNK
+	PUSH	BC			; SAVE LOOP CONTROL
+	LD	B,64			; READ 64 BYTES
+	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	INIR				; DO IT FAST
+	POP	BC			; RESTORE LOOP CONTROL
+#ELSE
+	; BYTE READ LOOP
+	PUSH	BC			; SAVE LOOP CONTROL
+	LD	B,64			; READ 64 BYTES
+CHUSB_READ2:
+	CALL	CH_RD			; GET NEXT BYTE
+	LD	(HL),A			; SAVE IT
+	INC	HL			; INC BUF PTR
+	DJNZ	CHUSB_READ2		; LOOP AS NEEDED
+	POP	BC			; RESTORE LOOP CONTROL
+#ENDIF
+;
+	; PREPARE FOR NEXT CHUNK
+	LD	A,CH_CMD_DSKRDGO	; CONTINUE DISK READ
+	CALL	CH_CMD			; SEND IT
+	DJNZ	CHUSB_READ1		; LOOP TILL DONE
+;
+	; FINAL CHECK FOR COMPLETION & SUCCESS
+	CALL	CH_POLL			; WAIT FOR COMPLETION
+	CP	$14			; SUCCESS?
+	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
+;
+	; INCREMENT LBA
+	PUSH	HL			; SAVE HL
+	LD	A,CHUSB_LBA		; LBA OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	INC32HL			; INCREMENT THE VALUE
+	POP	HL			; RESTORE HL
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+;
+;
+CHUSB_WRITE:
+	LD	A,CH_MODE_USB		; REQUEST USB MODE
+	CALL	CH_SETMODE		; DO IT
+	JP	NZ,CHUSB_CMDERR		; HANDLE ERROR
+;
+	CALL	HB_DSKWRITE		; HOOK HBIOS DISK WRITE SUPERVISOR
+	LD	(CHUSB_DSKBUF),HL	; SAVE DISK BUFFER ADDRESS
+	LD	A,CH_CMD_DSKWR		; DISK READ COMMAND
+	CALL	CHUSB_RWSTART		; SEND CMD AND LBA
+;
+	; WRITE THE SECTOR IN 64 BYTE CHUNKS
+	LD	B,8			; 8 CHUNKS OF 64 FOR 512 BYTE SECTOR
+	LD	HL,(CHUSB_DSKBUF)	; GET DISK BUF ADR
+CHUSB_WRITE1:
+	CALL	CH_POLL			; WAIT FOR DATA READY
+	CP	$1E			; DATA READY TO WRITE
+	;CALL	PC_GT			; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	JP	NZ,CHUSB_IOERR		; HANDLE IO ERROR
+	CALL	CH_CMD_WR		; SEND WRITE USB DATA CMD
+	LD	A,64			; 64 BYTE CHUNK
+	CALL	CH_WR			; SEND DATA BLOCK LENGTH
+;
+#IF (CHUSB_FASTIO)
+	; WRITE 64 BYTE CHUNK
+	PUSH	BC			; SAVE LOOP CONTROL
+	LD	B,64			; WRITE 64 BYTES
+	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	OTIR				; DO IT FAST
+	POP	BC			; RESTORE LOOP CONTROL
+#ELSE
+	; BYTE WRITE LOOP
+	PUSH	BC			; SAVE LOOP CONTROL
+	LD	B,64			; WRITE 64 BYTES
+CHUSB_WRITE2:
+	LD	A,(HL)			; GET NEXT BYTE
+	INC	HL			; INC BUF PTR
+	CALL	CH_WR			; WRITE NEXT BYTE
+	DJNZ	CHUSB_WRITE2		; LOOP AS NEEDED
+	POP	BC			; RESTORE LOOP CONTROL
+#ENDIF
+;
+	; PREPARE FOR NEXT CHUNK
+	LD	A,CH_CMD_DSKWRGO	; CONTINUE DISK READ
+	CALL	CH_CMD			; SEND IT
+	DJNZ	CHUSB_WRITE1		; LOOP TILL DONE
+;
+	; FINAL CHECK FOR COMPLETION & SUCCESS
+	CALL	CH_POLL			; WAIT FOR COMPLETION
+	CP	$14			; SUCCESS?
+	JP	NZ,CHUSB_IOERR		; IF NOT, HANDLE ERROR
+;
+	; INCREMENT LBA
+	PUSH	HL			; SAVE HL
+	LD	A,CHUSB_LBA		; LBA OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	INC32HL			; INCREMENT THE VALUE
+	POP	HL			; RESTORE HL
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; INITIATE A DISK SECTOR READ/WRITE OPERATION
+; A: READ OR WRITE OPCODE
+;
+CHUSB_RWSTART:
+	CALL	CH_CMD			; SEND R/W COMMAND
+;
+	; SEND LBA, 4 BYTES, LITTLE ENDIAN
+	LD	A,CHUSB_LBA		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	LD	B,4			; SEND 4 BYTES
+CHUSB_RWSTART1:
+	LD	A,(HL)			; GET BYTE
+	INC	HL			; BUMP PTR
+	CALL	CH_WR			; SEND BYTE
+	DJNZ	CHUSB_RWSTART1		; LOOP AS NEEDED
+;
+	; REQUEST 1 SECTOR
+	LD	A,1			; 1 SECTOR
+	CALL	CH_WR			; SEND IT
+	RET
+;
+;
+;
+CHUSB_STATUS:
+	; RETURN UNIT STATUS
+	LD	A,(IY+CHUSB_STAT)	; GET STATUS OF SELECTED DEVICE
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+; RESET THE INTERFACE AND REDISCOVER MEDIA
+;
+CHUSB_RESET:
+	;PRTS("\n\rRES USB:$")		; *DEBUG*
+	;CALL	CH_FLUSH		; DISCARD ANY GARBAGE
+	;CALL	CH_RESET		; FULL CH37X RESET
+;
+	; RESET THE BUS
+	LD	A,CH_CMD_MODE		; SET MODE COMMAND
+	CALL	CH_CMD			; SEND IT
+	LD	A,7			; RESET BUS
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP			; SMALL WAIT
+	CALL	CH_RD			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CALL	CH_NAP			; SMALL WAIT
+;
+	; ACTIVATE USB MODE
+	LD	A,CH_CMD_MODE		; SET MODE COMMAND
+	CALL	CH_CMD			; SEND IT
+	LD	A,6			; USB ENABLED, SEND SOF
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP			; SMALL WAIT
+	CALL	CH_RD			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CALL	CH_NAP			; SMALL WAIT
+;
+	LD	A,CH_MODE_USB		; WE ARE NOW IN USB MODE
+	LD	L,(IY+CHUSB_MODE+0)	; GET MODE PTR (LSB)
+	LD	H,(IY+CHUSB_MODE+1)	; GET MODE PTR (MSB)
+	LD	(HL),A			; SAVE IT
+;
+	; INITIALIZE DISK
+	LD	B,24			; TRY A FEW TIMES
+CHUSB_RESET1:
+	;PRTS("\n\rDSKINIT:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKINIT	; DISK INIT COMMAND
+	CALL	CH_CMD			; SEND IT
+	LD	DE,10000		; 10000 * 16 = 160US ???
+	LD	DE,20000		; 10000 * 16 = 160US ???
+	LD	DE,12500		; 1250 * 16 = 200US ???
+	CALL	VDELAY			; DELAY
+	CALL	CH_POLL			; WAIT FOR RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; SUCCESS?
+	JR	Z,CHUSB_RESET1A		; IF SO, CHECK READY
+	CP	$16			; NO MEDIA
+	JP	Z,CHUSB_NOMEDIA		; HANDLE IT
+	CALL	CH_NAP			; SMALL DELAY
+	DJNZ	CHUSB_RESET1		; LOOP AS NEEDED
+	JP	CHUSB_TO		; HANDLE TIMEOUT
+;
+CHUSB_RESET1A:
+	;CALL	CHUSB_DSKRES		; DISK RESET
+	;CP	$14			; GOOD?
+	;JR	Z,CHUSB_RESET2
+	;CALL	CHUSB_DSKRDY		; CHECK IF DISK READY
+	;CP	$14			; GOOD?
+	;JR	Z,CHUSB_RESET2		; IF SO, MOVE ON
+	;DJNZ	CHUSB_RESET1		; KEEP TRYING
+;
+CHUSB_RESET2:
+	; USE OF CH376 DISK_MOUNT COMMAND SEEMS TO IMPROVE
+	; COMPATIBILITY WITH SOME OLDER USB THUMBDRIVES.
+	LD	A,(IY+CH_TYPE)		; CH37X TYPE?
+	CP	CHTYP_376		; IS CH376?
+	CALL	Z,CHUSB_DSKMNT		; IF SO, TRY MOUNT, IGNORE ERRS
+	;CALL	CHUSB_AUTOSET		; *DEBUG*
+	;CALL	CHUSB_TSTCON		; *DEBUG*
+	;CALL	CHUSB_MAXLUN		; *DEBUG*
+	;CALL	CHUSB_DSKRDY		; *DEBUG*
+	;CALL	CHUSB_DSKINQ		; *DEBUG*
+;;
+	CALL	CHUSB_DSKSIZ		; GET AND RECORD DISK SIZE
+	RET	NZ			; ABORT ON ERROR
+;
+	; SET STATUS AND RETURN
+	XOR	A			; CLEAR STATUS
+	LD	(IY+CHUSB_STAT),A	; RECORD STATUS
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+;
+;
+CHUSB_DEVICE:
+	LD	D,DIODEV_CHUSB		; D := DEVICE TYPE
+	LD	E,(IY+CH_DEV)		; E := PHYSICAL DEVICE NUMBER
+	LD	C,%00110011		; USB HARD DISK ATTRIBUTES
+	LD	H,(IY+CH_TYPE)		; H := MODE
+	LD	L,(IY+CH_IOBASE)	; L := BASE I/O ADDRESS
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+; CHUSB_GETMED
+;
+CHUSB_MEDIA:
+	LD	A,E			; GET FLAGS
+	OR	A			; SET FLAGS
+	JR	Z,CHUSB_MEDIA1		; JUST REPORT CURRENT STATUS AND MEDIA
+	CALL	CHUSB_RESET		; RESET CHUSB INTERFACE
+;
+CHUSB_MEDIA1:
+	LD	A,(IY+CHUSB_STAT)	; GET STATUS
+	OR	A			; SET FLAGS
+	LD	D,0			; NO MEDIA CHANGE DETECTED
+	LD	E,MID_HD		; ASSUME WE ARE OK
+	RET	Z			; RETURN IF GOOD INIT
+	LD	E,MID_NONE		; SIGNAL NO MEDIA
+	LD	A,ERR_NOMEDIA		; NO MEDIA ERROR
+	OR	A			; SET FLAGS
+	RET				; AND RETURN
+;
+;
+;
+CHUSB_SEEK:
+	BIT	7,D			; CHECK FOR LBA FLAG
+	CALL	Z,HB_CHS2LBA		; CLEAR MEANS CHS, CONVERT TO LBA
+	RES	7,D			; CLEAR FLAG REGARDLESS (DOES NO HARM IF ALREADY LBA)
+	LD	(IY+CHUSB_LBA+0),L	; SAVE NEW LBA
+	LD	(IY+CHUSB_LBA+1),H	; ...
+	LD	(IY+CHUSB_LBA+2),E	; ...
+	LD	(IY+CHUSB_LBA+3),D	; ...
+	XOR	A			; SIGNAL SUCCESS
+	RET				; AND RETURN
+;
+;
+;
+CHUSB_CAP:
+	LD	A,(IY+CHUSB_STAT)	; GET STATUS
+	PUSH	AF			; SAVE IT
+	LD	A,CHUSB_MEDCAP		; OFFSET TO CAPACITY FIELD
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	CALL	LD32			; GET THE CURRENT CAPACITY INTO DE:HL
+	LD	BC,512			; 512 BYTES PER BLOCK
+	POP	AF			; RECOVER STATUS
+	OR	A			; SET FLAGS
+	RET
+;
+;
+;
+CHUSB_GEOM:
+	; FOR LBA, WE SIMULATE CHS ACCESS USING 16 HEADS AND 16 SECTORS
+	; RETURN HS:CC -> DE:HL, SET HIGH BIT OF D TO INDICATE LBA CAPABLE
+	CALL	CHUSB_CAP		; GET TOTAL BLOCKS IN DE:HL, BLOCK SIZE TO BC
+	LD	L,H			; DIVIDE BY 256 FOR # TRACKS
+	LD	H,E			; ... HIGH BYTE DISCARDED, RESULT IN HL
+	LD	D,16 | $80		; HEADS / CYL = 16, SET LBA CAPABILITY BIT
+	LD	E,16			; SECTORS / TRACK = 16
+	RET				; DONE, A STILL HAS CHUSB_CAP STATUS
+;
+; CH37X HELPER ROUTINES
+;
+;
+; PERFORM DISK MOUNT
+;
+CHUSB_DSKMNT:
+	;PRTS("\n\rMOUNT:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKMNT		; DISK QUERY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; SUCCESS?
+	RET	NZ			; ABORT IF NOT
+;
+#IF FALSE
+	CALL	CH_CMD_RD		; SEND READ COMMAND
+	CALL	CH_RD			; GET LENGTH
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	LD	B,A			; LOOP COUNTER
+	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
+CHUSB_DSKMNT1:
+	CALL	CH_RD			; GET A BYTE
+	LD	(HL),A			; SAVE IT
+	INC	HL			; BUMP BUF PTR
+	DJNZ	CHUSB_DSKMNT1		; LOOP FOR ALL DATA
+;
+	;LD	DE,HB_WRKBUF		; *DEBUG*
+	;CALL	DUMP_BUFFER		; *DEBUG*
+;
+	CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
+	LD	HL,HB_WRKBUF + 8
+	LD	B,28
+CHUSB_DSKMNT2:
+	LD	A,(HL)
+	INC	HL
+	CALL	COUT
+	DJNZ	CHUSB_DSKMNT2
+#ENDIF
+;
+	XOR	A
+	RET
+;
+; PERFORM DISK SIZE
+;
+CHUSB_DSKSIZ:
+	;PRTS("\n\rDSKSIZ:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKSIZ		; DISK SIZE COMMAND
+	CALL	CH_CMD			; SEND IT
+	CALL	CH_POLL			; WAIT FOR RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; SUCCESS?
+	JP	NZ,CHUSB_CMDERR		; HANDLE CMD ERROR
+	CALL	CH_CMD_RD		; SEND READ USB DATA CMD
+	CALL	CH_RD			; GET RD DATA LEN
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$08			; MAKE SURE IT IS 8
+	JP	NZ,CHUSB_CMDERR		; HANDLE CMD ERROR
+	LD	A,CHUSB_MEDCAP		; MEDIA CAPACITY OFFSET
+	CALL	LDHLIYA			; HL := IY + A, REG A TRASHED
+	PUSH	HL			; SAVE ADDRESS
+	CALL	CH_RD
+	LD	D,A
+	CALL	CH_RD
+	LD	E,A
+	CALL	CH_RD
+	LD	H,A
+	CALL	CH_RD
+	LD	L,A
+	CALL	CH_RD
+	CALL	CH_RD
+	CALL	CH_RD
+	CALL	CH_RD
+	POP	BC			; RECOVER ADDRESS TO BC
+	CALL	ST32			; STORE IT
+	XOR	A			; SIGNAL SUCCESS
+	RET				; AND DONE
+;
+#IF FALSE
+;
+; PERFORM DISK INQUIRY
+; BASICALLY THE SCSI INQUIRY COMMAND
+;
+CHUSB_DSKINQ:
+	;PRTS("\n\rINQUIRY:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKINQ		; DISK QUERY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; SUCCESS?
+	RET	NZ			; ABORT IF NOT
+	CALL	CH_CMD_RD		; SEND READ COMMAND
+	CALL	CH_RD			; GET LENGTH
+	LD	B,A			; LOOP COUNTER
+	LD	HL,HB_WRKBUF		; USE WORK BUFFER FOR DATA
+DSKINQ1:
+	CALL	CH_RD			; GET A BYTE
+	LD	(HL),A			; SAVE IT
+	INC	HL			; BUMP BUF PTR
+	DJNZ	DSKINQ1			; LOOP FOR ALL DATA
+;
+	;LD	DE,HB_WRKBUF		; *DEBUG*
+	;CALL	DUMP_BUFFER		; *DEBUG*
+;
+	;CALL	CHUSB_PRTPREFIX		; PRINT DEVICE PREFIX
+	;LD	HL,HB_WRKBUF + 8
+	;LD	B,28
+DSKINQ2:
+	;LD	A,(HL)
+	;INC	HL
+	;CALL	COUT
+	;DJNZ	DSKINQ2
+;
+	RET
+;
+; PERFORM SET RETRIES
+;
+CHUSB_SETRETRY:
+	;PRTS("\n\rSETRETRY:$")		; *DEBUG*
+	LD	A,CH_CMD_SETRETRY	; DISK READY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_NAP
+	LD	A,$25			; CONSTANT
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP
+	LD	A,$BF			; MAX
+	CALL	CH_WR
+	CALL	CH_NAP
+	CALL	CH_RD			; GET RESULT
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+	RET
+;
+; PERFORM DISK RESET
+;
+CHUSB_DSKRES:
+	;PRTS("\n\rDSKRES:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKRES		; DISK READY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+	RET
+;
+; PERFORM DISK READY
+;
+CHUSB_DSKRDY:
+	;PRTS("\n\rDSKRDY:$")		; *DEBUG*
+	LD	A,CH_CMD_DSKRDY		; DISK READY
+	CALL	CH_CMD			; DO IT
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+	CP	$14			; *DEBUG*
+	JR	NZ,CHUSB_DSKRDY		; *DEBUG*
+;
+	RET
+;
+; PERFORM AUTO SETUP
+;
+CHUSB_AUTOSET:
+	;PRTS("\n\rAUTOSET:$")		; *DEBUG*
+	LD	A,CH_CMD_AUTOSET	; AUTOMATIC SETUP FOR USB
+	CALL	CH_CMD			; DO IT
+	CALL	LDELAY			; *DEBUG*
+	CALL	CH_POLL			; WAIT FOR RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+	RET
+;
+; PERFORM TEST CONNECT
+;
+CHUSB_TSTCON:
+	;PRTS("\n\rTSTCON:$")		; *DEBUG*
+	LD	A,CH_CMD_TSTCON		; TEST USB DEVICE CONNECT
+	CALL	CH_CMD			; DO IT
+	CALL	CH_NAP			; WAIT A BIT
+	CALL	CH_RD			; GET RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+	RET
+;
+; PERFORM GET MAX LUN
+;
+CHUSB_MAXLUN:
+	;PRTS("\n\rMAXLUN:$")		; *DEBUG*
+	LD	A,CH_CMD_MAXLUN		; TEST USB DEVICE CONNECT
+	CALL	CH_CMD			; DO IT
+	CALL	CH_NAP			; WAIT A BIT
+	LD	A,$38			; CONSTANT
+	CALL	CH_WR			; SEND IT
+	CALL	CH_NAP
+	CALL	CH_RD			; GET RESPONSE
+	;CALL	PC_SPACE		; *DEBUG*
+	;CALL	PRTHEXBYTE		; *DEBUG*
+;
+	RET
+;
+#ENDIF
+;
+; ERROR HANDLERS
+;
+;
+CHUSB_NOMEDIA:
+	LD	A,CHUSB_STNOMEDIA
+	JR	CHUSB_ERR
+;
+CHUSB_CMDERR:
+	LD	A,CHUSB_STCMDERR
+	JR	CHUSB_ERR
+;
+CHUSB_IOERR:
+	LD	A,CHUSB_STIOERR
+	JR	CHUSB_ERR
+;
+CHUSB_TO:
+	LD	A,CHUSB_STTO
+	JR	CHUSB_ERR
+;
+CHUSB_NOTSUP:
+	LD	A,CHUSB_STNOTSUP
+	JR	CHUSB_ERR
+;
+CHUSB_ERR:
+	LD	(IY+CHUSB_STAT),A	; SAVE NEW STATUS
+;
+CHUSB_ERR2:
+#IF (CHUSBTRACE >= 2)
+	CALL	CHUSB_PRTSTAT
+#ENDIF
+	OR	A			; SET FLAGS
+	RET
+;
+;
+;
+CHUSB_PRTERR:
+	RET	Z			; DONE IF NO ERRORS
+	; FALL THRU TO CHUSB_PRTSTAT
+;
+; PRINT FULL DEVICE STATUS LINE
+;
+CHUSB_PRTSTAT:
+	PUSH	AF
+	PUSH	DE
+	PUSH	HL
+	LD	A,(IY+CHUSB_STAT)
+	CALL	CHUSB_PRTPREFIX		; PRINT UNIT PREFIX
+	CALL	PC_SPACE		; FORMATTING
+	CALL	CHUSB_PRTSTATSTR
+	POP	HL
+	POP	DE
+	POP	AF
+	RET
+;
+; PRINT STATUS STRING
+;
+CHUSB_PRTSTATSTR:
+	PUSH	AF
+	PUSH	DE
+	PUSH	HL
+	LD	A,(IY+CHUSB_STAT)
+	NEG
+	LD	HL,CHUSB_STR_ST_MAP
+	ADD	A,A
+	CALL	ADDHLA
+	LD	E,(HL)
+	INC	HL
+	LD	D,(HL)
+	CALL	WRITESTR
+	POP	HL
+	POP	DE
+	POP	AF
+	RET
+;
+; PRINT DIAGNONSTIC PREFIX
+;
+CHUSB_PRTPREFIX:
+	PUSH	AF
+	CALL	NEWLINE
+	PRTS("CHUSB$")
+	LD	A,(IY+CH_DEV)		; GET CURRENT DEVICE NUM
+	CALL	PRTDECB
+	CALL	PC_COLON
+	POP	AF
+	RET
+;
+; DATA STORAGE
+;
+CHUSB_DEVNUM	.DB	0		; TEMP DEVICE NUM USED DURING INIT
+CHUSB_DSKBUF	.DW	0
+;
+CHUSB_STR_ST_MAP:
+	.DW		CHUSB_STR_STOK
+	.DW		CHUSB_STR_STNOMEDIA
+	.DW		CHUSB_STR_STCMDERR
+	.DW		CHUSB_STR_STIOERR
+	.DW		CHUSB_STR_STTO
+	.DW		CHUSB_STR_STNOTSUP
+;
+CHUSB_STR_STOK		.TEXT	"OK$"
+CHUSB_STR_STNOMEDIA	.TEXT	"NO MEDIA$"
+CHUSB_STR_STCMDERR	.TEXT	"COMMAND ERROR$"
+CHUSB_STR_STIOERR	.TEXT	"IO ERROR$"
+CHUSB_STR_STTO		.TEXT	"TIMEOUT$"
+CHUSB_STR_STNOTSUP	.TEXT	"NOT SUPPORTED$"
+CHUSB_STR_STUNK		.TEXT	"UNKNOWN ERROR$"
diff --git a/Source/HBIOS/ctc.asm b/Source/HBIOS/ctc.asm
index 364b849b..777b28f8 100644
--- a/Source/HBIOS/ctc.asm
+++ b/Source/HBIOS/ctc.asm
@@ -162,7 +162,9 @@ CTCTIVT		.EQU	INT_CTC0A + CTCTIMCH
 ;==================================================================================================
 ;
 CTC_PREINIT:
-	; BLINDLY RESET THE CTC ASSUMING IT IS THERE
+	; BLINDLY RESET THE CTC ASSUMING IT IS THERE.  PER ALAN COX
+	; THE CTC CONFIGURATION IS UNDEFINED AT STARTUP.  THIS SHOULD
+	; PRECLUDE POSSIBLE EXTRANEOUS INTERRUPTS.
 	LD	A,CTC_DEFCFG
 	OUT	(CTCBASE),A
 	OUT	(CTCBASE+1),A
diff --git a/Source/ver.inc b/Source/ver.inc
index d8cdd1ce..137203d7 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,7 +2,7 @@
 #DEFINE	RMN	4
 #DEFINE	RUP	0
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.4.0-dev.37"
+#DEFINE BIOSVER	"3.4.0-dev.38"
 #define rmj	RMJ
 #define rmn	RMN
 #define rup	RUP
diff --git a/Source/ver.lib b/Source/ver.lib
index 54c608fb..745f88e1 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	4
 rup	equ	0
 rtp	equ	0
 biosver	macro
-	db	"3.4.0-dev.37"
+	db	"3.4.0-dev.38"
 	endm