Update sd.asm

Refinements to sd.asm for RC2014 WizNet Module (SDMODE_MT).

Source/HBIOS/sd.asm

@@ -9,14 +9,14 @@
 ;    - TEST XC CARD TYPE DETECTION
 ;    - TRY TO GET INIT TO FAIL, REMOVE DELAYS AT START OF GOIDLE?
 ;
-;--------------------------------------------------------------------------------------
-; SD Signal	Active	JUHA	N8	CSIO	PPI	UART	DSD	MK4      SC
-; ------------	------- ------- ------- ------- ------- ------- ------- -------	------- 
-; CS (DAT3)	LO ->	RTC:2	RTC:2	RTC:2	~PC:4	~MCR:3	OPR:2	SD:2	~RTC:2	
-; CLK		HI ->	RTC:1	RTC:1	CSIO	PC:1	~MCR:2	OPR:1	CSIO	CSIO
-; DI (CMD)	HI ->	RTC:0	RTC:0	CSIO	PC:0	~MCR:0	OPR:0	CSIO	CSIO
-; DO (DAT0)	HI ->	RTC:7	RTC:6	CSIO	PB:7	~MSR:5	OPR:0	CSIO	CSIO
-;--------------------------------------------------------------------------------------
+;----------------------------------------------------------------------------------------------
+; SD Signal	Active	JUHA	N8	CSIO	PPI	UART	DSD	MK4	SC	MT
+; ------------	------- ------- ------- ------- ------- ------- ------- -------	-------	------- 
+; CS (DAT3)	LO ->	RTC:2	RTC:2	RTC:2	~PC:4	~MCR:3	OPR:2	SD:2	~RTC:2/3OPR:4/5	
+; CLK		HI ->	RTC:1	RTC:1	CSIO	PC:1	~MCR:2	OPR:1	CSIO	CSIO	SPI
+; DI (CMD)	HI ->	RTC:0	RTC:0	CSIO	PC:0	~MCR:0	OPR:0	CSIO	CSIO	SPI
+; DO (DAT0)	HI ->	RTC:7	RTC:6	CSIO	PB:7	~MSR:5	OPR:0	CSIO	CSIO	SPI
+;----------------------------------------------------------------------------------------------
 ;
 ; CS = CHIP SELECT (AKA DAT3 FOR NON-SPI MODE)
 ; CLK = CLOCK
@@ -120,7 +120,7 @@ SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
 SD_OPRREG	.EQU	RTCIO		; USES RTC LATCHES FOR OPERATION
 SD_OPRDEF	.EQU	%00000001	; QUIESCENT STATE
 SD_INPREG	.EQU	RTCIO		; INPUT REGISTER IS RTC
-SD_CS		.EQU	%00000100	; RTC:2 IS SELECT
+SD_CS0		.EQU	%00000100	; RTC:2 IS SELECT
 SD_CLK		.EQU	%00000010	; RTC:1 IS CLOCK
 SD_DI		.EQU	%00000001	; RTC:0 IS DATA IN (CARD <- CPU)
 SD_DO		.EQU	%10000000	; RTC:7 IS DATA OUT (CARD -> CPU)
@@ -131,7 +131,7 @@ SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
 SD_OPRREG	.EQU	RTCIO		; USES RTC LATCHES FOR OPERATION
 SD_OPRDEF	.EQU	%00000001	; QUIESCENT STATE
 SD_INPREG	.EQU	RTCIO		; INPUT REGISTER IS RTC
-SD_CS		.EQU	%00000100	; RTC:2 IS SELECT
+SD_CS0		.EQU	%00000100	; RTC:2 IS SELECT
 SD_CLK		.EQU	%00000010	; RTC:1 IS CLOCK
 SD_DI		.EQU	%00000001	; RTC:0 IS DATA IN (CARD <- CPU)
 SD_DO		.EQU	%01000000	; RTC:6 IS DATA OUT (CARD -> CPU)
@@ -141,7 +141,7 @@ SD_DO		.EQU	%01000000	; RTC:6 IS DATA OUT (CARD -> CPU)
 SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
 SD_OPRREG	.EQU	RTCIO		; USES RTC LATCHES FOR OPERATION
 SD_OPRDEF	.EQU	%00000000	; QUIESCENT STATE
-SD_CS		.EQU	%00000100	; RTC:2 IS SELECT
+SD_CS0		.EQU	%00000100	; RTC:2 IS SELECT
 SD_CNTR		.EQU	Z180_CNTR
 SD_TRDR		.EQU	Z180_TRDR
 #ENDIF
@@ -155,7 +155,7 @@ SD_PPIX		.EQU	PPIBASE + 3	; PPI CONTROL PORT
 SD_OPRREG	.EQU	SD_PPIC		; PPI PORT C IS OPR REG
 SD_OPRDEF	.EQU	%00110001	; CS HI, DI HI
 SD_INPREG	.EQU	SD_PPIB		; INPUT REGISTER IS PPI PORT B
-SD_CS		.EQU	%00010000	; PPIC:4 IS SELECT
+SD_CS0		.EQU	%00010000	; PPIC:4 IS SELECT
 SD_CLK		.EQU	%00000010	; PPIC:1 IS CLOCK
 SD_DI		.EQU	%00000001	; PPIC:0 IS DATA IN (CARD <- CPU)
 SD_DO		.EQU	%10000000	; PPIB:7 IS DATA OUT (CARD -> CPU)
@@ -166,7 +166,7 @@ SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
 SD_OPRREG	.EQU	SIO_MCR		; UART MCR PORT (OUTPUT: CS, CLK, DIN)
 SD_OPRDEF	.EQU	%00001100	; QUIESCENT STATE
 SD_INPREG	.EQU	SIO_MSR		; INPUT REGISTER IS MSR
-SD_CS		.EQU	%00001000	; UART MCR:3 IS SELECT
+SD_CS0		.EQU	%00001000	; UART MCR:3 IS SELECT
 SD_CLK		.EQU	%00000100	; UART MCR:2 IS CLOCK
 SD_DI		.EQU	%00000001	; UART MCR:0 IS DATA IN (CARD <- CPU)
 SD_DO		.EQU	%00100000	; UART MSR:5 IS DATA OUT (CARD -> CPU)
@@ -179,7 +179,7 @@ SD_OPRDEF	.EQU	%00000001	; QUIESCENT STATE
 SD_INPREG	.EQU	SD_OPRREG	; INPUT REGISTER IS OPRREG
 SD_SELREG	.EQU	SD_OPRREG + 1	; DEDICATED SELECTION REGISTER
 SD_SELDEF	.EQU	%00000000	; SELECTION REGISTER DEFAULT
-SD_CS		.EQU	%00000100	; RTC:2 IS SELECT
+SD_CS0		.EQU	%00000100	; RTC:2 IS SELECT
 SD_CLK		.EQU	%00000010	; RTC:1 IS CLOCK
 SD_DI		.EQU	%00000001	; RTC:6 IS DATA IN (CARD <- CPU)
 SD_DO		.EQU	%00000001	; RTC:0 IS DATA OUT (CARD -> CPU)
@@ -189,7 +189,7 @@ SD_DO		.EQU	%00000001	; RTC:0 IS DATA OUT (CARD -> CPU)
 SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
 SD_OPRREG	.EQU	$89		; DEDICATED MK4 SDCARD REGISTER
 SD_OPRDEF	.EQU	%00000000	; QUIESCENT STATE
-SD_CS		.EQU	%00000100	; SELECT ACTIVE
+SD_CS0		.EQU	%00000100	; SELECT ACTIVE
 SD_CNTR		.EQU	Z180_CNTR
 SD_TRDR		.EQU	Z180_TRDR
 #ENDIF
@@ -205,19 +205,25 @@ SD_TRDR		.EQU	Z180_TRDR
 #ENDIF
 ;
 #IF (SDMODE == SDMODE_MT)		; MT shift register for RC2014 (ref SDMODE_CSIO)
-SD_BASE		.EQU	%01011100	; Dedicated base address $5C
-SD_DEVCNT	.EQU	1		; NUMBER OF PHYSICAL UNITS (SOCKETS)
-SD_OPRREG	.EQU	SD_BASE+2	; SD CHIP SELECTOR
-SD_OPRDEF	.EQU	%00100000	; QUIESCENT STATE
-SD_CD0		.EQU	%00000001	; IN/OUT:SD_OPREG:0 = CD0, PMOD pull CD0 low
-SD_CD1		.EQU	%00000010	; IN:SD_OPREG:1 = CD1, IN=0 Card detect switch
-SD_CD2		.EQU	%00000100	; IN:SD_OPREG:2 = CD2, IN=0 Card detect switch
-ENETCS0		.EQU	%00001000	; IN/OUT:SD_OPREG:3 = CS0, PMOD SPI CS
-SDCS1		.EQU	%00010000	; IN/OUT:SD_OPREG:4 = CS1, SDCARD1 CS, IN=1 Card present
-PARK		.EQU	%00100000	; IN/OUT:SD_OPREG:5 = CS2, SDCARD2 CS, IN=1 Card present
-SD_WRTR		.EQU	%01011100	; Write data and transfer
-SD_RDTR		.EQU	%01011101	; Read data and transfer
-SD_RDNTR	.EQU	%01011100	; Read data and NO transfer
+;
+; 3 SPI CHANNELS.  CHANNEL 0 (CDX & CSX) IS A DEDICATED CONNECTION TO ONBOARD
+; WIZNET W5500 AND IS NOT USED HERE.  CHANNEL 1 (CD0 & CS0) & 2 (CD1 & CS1)
+; ARE ASSUMED TO BE CONNECTED TO SD CARDS.
+;
+SD_BASE		.EQU	$5C		; Module base address
+SD_DEVCNT	.EQU	2		; NUMBER OF PHYSICAL UNITS (SOCKETS)
+SD_WRTR		.EQU	SD_BASE + 0	; Write data and transfer
+SD_RDTR		.EQU	SD_BASE + 1	; Read data and transfer
+SD_RDNTR	.EQU	SD_BASE	+ 0	; Read data and NO transfer
+SD_OPRREG	.EQU	SD_BASE + 2	; SD CHIP SELECTOR
+SD_OPRDEF	.EQU	%00000000	; QUIESCENT STATE
+SD_CDX		.EQU	%00000001	; IN/OUT:SD_OPREG:0 = CD0, PMOD pull CD0 low
+SD_CD0		.EQU	%00000010	; IN:SD_OPREG:1 = CD1, IN=0 Card detect switch
+SD_CD1		.EQU	%00000100	; IN:SD_OPREG:2 = CD2, IN=0 Card detect switch
+SD_CSX		.EQU	%00001000	; IN/OUT:SD_OPREG:3 = CS0, PMOD SPI CS
+SD_CS0		.EQU	%00010000	; IN/OUT:SD_OPREG:4 = CS1, SDCARD1 CS, IN=1 Card present
+SD_CS1		.EQU	%00100000	; IN/OUT:SD_OPREG:5 = CS2, SDCARD2 CS, IN=1 Card present
+
 #ENDIF
 ;
 ; SD CARD COMMANDS
@@ -413,7 +419,7 @@ SD_INIT:
 #IF (SDMODE == SDMODE_MT)
 	PRTS(" MODE=MT$")
 	PRTS(" IO=0x$")
-	LD	A,SD_OPRREG
+	LD	A,SD_BASE
 	CALL	PRTHEXBYTE
 #ENDIF
 ;
@@ -577,50 +583,51 @@ SD_PROBE:
 	RET				; RETURN W/ ZF SET AS NEEDED
 #ENDIF
 ;
-#IF (SDMODE == SDMODE_MT)
-	LD	A,SD_OPRDEF
-	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
-	; TEST WITH PMOD NOT CONNECTED
-;	IN	A,(SD_OPRREG)
-;	AND	SD_CD0+SD_CS0		; ISOLATE CD0 AND CS0
-;	CP	SD_CD0+SD_CS0		; BOTH SHOULD BE HIGH
-;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT
-	; TEST CD0
-;	LD	A,SD_CD0		; D1=DNP CANNOT TEST
-;	OUT	(SD_OPRREG),A
-;	IN	A,(SD_OPRREG)
-;	AND	SD_CD0
-;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
-	; TEST CS0
-;	LD	A,SD_CS0		; D2=DNP CANNOT TEST
-;	OUT	(SD_OPRREG),A
-;	IN	A,(SD_OPRREG)
-;	AND	SD_CS0
-;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
-	; TEST CS1
-;	LD	A,SD_CS1
-;	OUT	(SD_OPRREG),A
-;	IN	A,(SD_OPRREG)
-;	AND	SD_CS1
-;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
-;	; TEST CS2
-;	LD	A,SD_CS2
-;	OUT	(SD_OPRREG),A
-;	IN	A,(SD_OPRREG)
-;	AND	SD_CS2
-;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
-
-	LD	A,SD_OPRDEF
-	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
-#ENDIF
+;#IF (SDMODE == SDMODE_MT)
+;	LD	A,SD_OPRDEF
+;	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
+;;
+;	; TEST WITH PMOD NOT CONNECTED
+;;	IN	A,(SD_OPRREG)
+;;	AND	SD_CD0+SD_CS0		; ISOLATE CD0 AND CS0
+;;	CP	SD_CD0+SD_CS0		; BOTH SHOULD BE HIGH
+;;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT
+;	; TEST CD0
+;;	LD	A,SD_CD0		; D1=DNP CANNOT TEST
+;;	OUT	(SD_OPRREG),A
+;;	IN	A,(SD_OPRREG)
+;;	AND	SD_CD0
+;;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
+;	; TEST CS0
+;;	LD	A,SD_CS0		; D2=DNP CANNOT TEST
+;;	OUT	(SD_OPRREG),A
+;;	IN	A,(SD_OPRREG)
+;;	AND	SD_CS0
+;;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
+;	; TEST CS1
+;;	LD	A,SD_CS1
+;;	OUT	(SD_OPRREG),A
+;;	IN	A,(SD_OPRREG)
+;;	AND	SD_CS1
+;;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
+;;	; TEST CS2
+;;	LD	A,SD_CS2
+;;	OUT	(SD_OPRREG),A
+;;	IN	A,(SD_OPRREG)
+;;	AND	SD_CS2
+;;	JR	NZ,SD_PROBE_FAIL	; FAIL IF NOT PULLED LOW
+;
+;	LD	A,SD_OPRDEF
+;	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
+;#ENDIF
 ;
 	XOR	A			; SIGNAL SUCCESS
 ;
-#IF (SDMODE == SDMODE_MT)
-SD_PROBE_FAIL:
-	LD	A,SD_OPRDEF
-	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
-#ENDIF
+;#IF (SDMODE == SDMODE_MT)
+;SD_PROBE_FAIL:
+;	LD	A,SD_OPRDEF
+;	OUT	(SD_OPRREG),A		; MAKE SURE CONTROL REGISTER IS CLEARED
+;#ENDIF
 	RET				; AND RETURN
 ;
 ;=============================================================================
@@ -830,13 +837,6 @@ SD_INITCARD:
 	JP	Z,SD_NOMEDIA		; Z=NO MEDIA, HANDLE IF SO
 ;
 	; WAKE UP THE CARD, KEEP DIN HI (ASSERTED) AND /CS HI (DEASSERTED)
-#IF (SDMODE == SDMODE_MT)
-	LD	A,$FF
-	LD	B,$10	; MIN 74 CLOCKS REQUIRED, WE USE 128 ($10 * 8)
-SD_INITCARD1:
-	OUT	(SD_WRTR),A		; SEND 8 CLOCKS
-	DJNZ	SD_INITCARD1
-#ELSE
 	LD	B,$10	; MIN 74 CLOCKS REQUIRED, WE USE 128 ($10 * 8)
 SD_INITCARD1:
 	LD	A,$FF			; KEEP DIN HI
@@ -844,7 +844,6 @@ SD_INITCARD1:
 	CALL	SD_PUT			; SEND 8 CLOCKS
 	POP	BC			; RESTORE LOOP CONTROL
 	DJNZ	SD_INITCARD1		; LOOP AS NEEDED
-#ENDIF
 ;
 	; PUT CARD IN IDLE STATE
 	CALL	SD_GOIDLE		; GO TO IDLE
@@ -875,9 +874,9 @@ SD_INITCARD3:
 	CALL	VDELAY			; CPU SPEED NORMALIZED DELAY
 	; SEND APP CMD INTRODUCER
 	CALL	SD_EXECACMD		; SEND APP COMMAND INTRODUCER
-#IF (SDMODE == SDMODE_MT)
-	CALL	NZ,SD_EXECACMD		; retry any fail
-#ENDIF
+;#IF (SDMODE == SDMODE_MT)
+;	CALL	NZ,SD_EXECACMD		; retry any fail
+;#ENDIF
 	CP	SD_STCMDERR		; COMMAND ERROR?
 	JR	Z,SD_INITCARD3A		; IF SO, TRY MMC CARD INIT
 	OR	A			; SET FLAGS
@@ -936,11 +935,7 @@ SD_INITCARD4:
 	CALL	SD_EXECCMD		; EXECUTE COMMAND
 	RET	NZ			; ABORT ON ERROR
 	; CMD58 WORKED, GET OCR DATA AND SET CARD TYPE
-#IF (SDMODE == SDMODE_MT)
-	IN	A,(SD_RDTR)		; BITS 31-24
-#ELSE
 	CALL	SD_GET			; BITS 31-24
-#ENDIF
 	CALL	SD_DONE			; FINISH THE TRANSACTION
 	AND	$40			; ISOLATE BIT 30 (CCS)
 	LD	C,SD_TYPESDSC		; ASSUME V1 CARD
@@ -1303,16 +1298,6 @@ SD_EXECCMD:
 SD_EXECCMD0:
 	; SEND THE COMMAND
 	LD	HL,SD_CMDBUF		; POINT TO COMMAND BUFFER
-#IF (SDMODE == SDMODE_MT)
-;	OUT	(SD_WRTR),A		; SEND IT
-	LD	C,SD_WRTR
-	OUTI
-	OUTI
-	OUTI
-	OUTI
-	OUTI
-	OUTI
-#ELSE
 	LD	E,6			; COMMANDS ARE 6 BYTES
 SD_EXECCMD1:
 	LD	A,(HL)			; PREPARE TO SEND NEXT BYTE
@@ -1320,31 +1305,15 @@ SD_EXECCMD1:
 	INC	HL			; POINT TO NEXT BYTE
 	DEC	E			; DEC LOOP COUNTER
 	JR	NZ,SD_EXECCMD1		; LOOP TILL DONE W/ ALL 6 BYTES
-#ENDIF
 ;
 #IF (SD_NOPULLUP)
 	; THE FIRST FILL BYTE IS DISCARDED!  THIS HACK IS REQUIRED BY
 	; STUPID SD CARD ADAPTERS THAT NOW OMIT THE MISO PULL-UP.  SEE
 	; COMMENTS AT TOP OF THIS FILE.
-  #IF (SDMODE == SDMODE_MT)
-	IN	A,(SD_RDTR)		; GET A BYTE AND DISCARD IT
-  #ELSE
 	CALL	SD_GET			; GET A BYTE AND DISCARD IT
-  #ENDIF
 #ENDIF
 ;
 	; GET RESULT
-#IF (SDMODE == SDMODE_MT)
-	; 256 loops might not be long enough timeout
-	; when only IN is required to read data
-	LD	E,0			; INIT TIMEOUT LOOP COUNTER
-SD_EXECCMD2:
-	IN	A,(SD_RDTR)		; GET A BYTE FROM THE CARD
-	OR	A			; SET FLAGS
-	JP	P,SD_EXECCMD3		; IF HIGH BIT IS 0, WE HAVE RESULT
-	DEC	E			; OTHERWISE DECREMENT LOOP COUNTER
-	JR	NZ,SD_EXECCMD2		; AND LOOP UNTIL TIMEOUT
-#ELSE
 	LD	E,0			; INIT TIMEOUT LOOP COUNTER
 SD_EXECCMD2:
 	CALL	SD_GET			; GET A BYTE FROM THE CARD
@@ -1352,7 +1321,6 @@ SD_EXECCMD2:
 	JP	P,SD_EXECCMD3		; IF HIGH BIT IS 0, WE HAVE RESULT
 	DEC	E			; OTHERWISE DECREMENT LOOP COUNTER
 	JR	NZ,SD_EXECCMD2		; AND LOOP UNTIL TIMEOUT
-#ENDIF
 	JP	SD_ERRCMDTO
 ;
 SD_EXECCMD3:
@@ -1524,11 +1492,7 @@ SD_PUTDATA3:
 SD_WAITRDY:
 	LD	DE,$FFFF		; LOOP MAX (TIMEOUT)
 SD_WAITRDY1:
-#IF (SDMODE == SDMODE_MT)
-	IN	A,(SD_RDTR)
-#ELSE
 	CALL	SD_GET
-#ENDIF
 	INC	A			; $FF -> $00
 	RET	Z			; IF READY, RETURN
 	DEC	DE
@@ -1552,11 +1516,7 @@ SD_WAITRDY1:
 SD_DONE:
 	PUSH	AF
 	LD	A,$FF
-#IF (SDMODE == SDMODE_MT)
-	OUT	(SD_WRTR),A
-#ELSE
 	CALL	SD_PUT
-#ENDIF
 	CALL	SD_DESELECT
 	POP	AF
 	RET
@@ -1589,14 +1549,14 @@ SD_SETUP:
 	OUT	(SD_OPRREG),A
 #ENDIF
 ;
-#IF ((SDMODE == SDMODE_MK4) | (SDMODE == SDMODE_DSD) | (SDMODE == SDMODE_PPI))
+#IF ((SDMODE == SDMODE_MK4) | (SDMODE == SDMODE_DSD) | (SDMODE == SDMODE_PPI)| (SDMODE == SDMODE_MT))
 	LD	A,SD_OPRDEF
 	LD	(SD_OPRVAL),A
 	OUT	(SD_OPRREG),A
 #ENDIF
 ;
 #IF (SDMODE == SDMODE_UART)
-SD_OPRMSK	.EQU	(SD_CS | SD_CLK | SD_DI)
+SD_OPRMSK	.EQU	(SD_CS0 | SD_CLK | SD_DI)
 	IN	A,(SD_OPRREG)		; OPRREG == SIO_MCR
 	AND	~SD_OPRMSK		; MASK OFF SD CONTROL BITS
 	OR	SD_OPRDEF		; SET DEFAULT BITS
@@ -1645,34 +1605,29 @@ SD_CHKWP:
 ; SELECT CARD
 ;
 SD_SELECT:
-	LD	A,(SD_OPRVAL)
-#IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
-  #IF (SDMODE == SDMODE_SC)
 	LD	A,(IY+SD_DEV)		; GET CURRENT DEVICE
 	OR	A			; SET FLAGS
 	LD	A,(SD_OPRVAL)		; GET CURRENT OPRVAL BACK
 	JR	NZ,SD_SELECT1		; IF NOT ZERO, DO SECONDARY
-	; ASSERT PRIMARY CS, DEASSERT SECONDARY
-	AND	~SD_CS0
-	OR	SD_CS1
+	; ASSERT PRIMARY CS, DEASSERT SECONDARY (IF ANY)
+	OR	SD_CS0
+#IF (SD_DEVCNT > 1)
+	AND	~SD_CS1
+#ENDIF
 	JR	SD_SELECT2
 SD_SELECT1:
-	; DEASSERT PRIMARY CS, ASSERT SECONDARY
-	OR	SD_CS0
-	AND	~SD_CS1
+	; DEASSERT PRIMARY CS, ASSERT SECONDARY (IF ANY)
+	AND	~SD_CS0
+#IF (SD_DEVCNT > 1)
+	OR	SD_CS1
+#ENDIF
 SD_SELECT2:
+; ADJUST BIT(S) FOR INTERFACES USING INVERTED CS BITS
+#IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
+  #IF (SD_DEVCNT > 1)
+	XOR	SD_CS0 | SD_CS1
   #ELSE
-	AND	~SD_CS			; SET SD_CS (CHIP SELECT)
-  #ENDIF
-#ELSE
-  #IF (SDMODE == SDMODE_MT)
-	LD	A,SDCS1
-SD_SELECT3:
-	LD	D,A
-	LD	A,(SD_OPRVAL)
-	OR	D			
-  #ELSE
-	OR	SD_CS			; SET SD_CS (CHIP SELECT)
+	XOR	SD_CS0
   #ENDIF
 #ENDIF
 	LD	(SD_OPRVAL),A
@@ -1683,18 +1638,17 @@ SD_SELECT3:
 ;
 SD_DESELECT:
 	LD	A,(SD_OPRVAL)
-#IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
-  #IF (SDMODE == SDMODE_SC)
-	OR	SD_CS0			; RESET PRIMARY CHIP SELECT
-	OR	SD_CS1			; RESET SECONDARY CHIP SELECT
-  #ELSE
-	OR	SD_CS			; RESET SD_CS (CHIP SELECT)
-  #ENDIF
+#IF (SD_DEVCNT > 1)
+	AND	~(SD_CS0 | SD_CS1)
 #ELSE
-  #IF (SDMODE == SDMODE_MT)
-	LD	A,PARK			; WHY IS PARK (CS2) BEING ASSERTED HERE???
+	AND	~SD_CS0
+#ENDIF
+; ADJUST BIT(S) FOR INTERFACES USING INVERTED CS BITS
+#IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
+  #IF (SD_DEVCNT > 1)
+	XOR	SD_CS0 | SD_CS1
   #ELSE
-	AND	~SD_CS			; RESET SD_CS (CHIP SELECT)
+	XOR	SD_CS0
   #ENDIF
 #ENDIF
 	LD	(SD_OPRVAL),A
@@ -1723,9 +1677,12 @@ SD_WAITRX:
 ;
 ; SEND ONE BYTE
 ;
-#IF (SDMODE != SDMODE_MT)		; SDMODE_MT uses "OUT  (SD_WRTR),A"
-;
 SD_PUT:
+;
+#IF (SDMODE == SDMODE_MT)
+	OUT	(SD_WRTR),A
+#ELSE
+;
   #IF ((SDMODE == SDMODE_CSIO) | (SDMODE == SDMODE_MK4) | (SDMODE == SDMODE_SC))
 	CALL	MIRROR			; MSB<-->LSB MIRROR BITS, RESULT IN C
 	CALL	SD_WAITTX		; MAKE SURE WE ARE DONE SENDING
@@ -1753,14 +1710,17 @@ SD_PUT1:
 	LD	A,(SD_OPRVAL)		; LOAD CURRENT OPR VALUE
 	OUT	(SD_OPRREG),A		; LEAVE WITH CLOCK LOW
   #ENDIF
-	RET				; DONE
 #ENDIF
+	RET				; DONE
 ;
 ; RECEIVE ONE BYTE
 ;
-#IF (SDMODE != SDMODE_MT)		; SDMODE_MT uses "IN  A,(SD_RDTR)"
 ;
 SD_GET:
+;
+#IF (SDMODE == SDMODE_MT)
+	IN	A,(SD_RDTR)
+#ELSE
   #IF ((SDMODE == SDMODE_CSIO) | (SDMODE == SDMODE_MK4) | (SDMODE == SDMODE_SC))
 	CALL	SD_WAITTX		; MAKE SURE WE ARE DONE SENDING
 	IN0	A,(Z180_CNTR)		; GET CSIO STATUS
@@ -1801,8 +1761,8 @@ SD_GET1:
 	XOR	$FF			; DO IS INVERTED ON UART
     #ENDIF
   #ENDIF
-	RET
 #ENDIF
+	RET
 ;
 ;=============================================================================
 ; ERROR HANDLING AND DIAGNOSTICS
@@ -1857,7 +1817,9 @@ SD_ERR2:
 	CALL	SD_PRTSTAT
 	CALL	SD_REGDUMP
 #ENDIF
+	PUSH	AF
 	CALL	SD_DESELECT		; De-select if there was an error
+	POP	AF
 	OR	A			; SET FLAGS
 	RET
 ;