diff --git a/Source/HBIOS/espsd.asm b/Source/HBIOS/espsd.asm
index e99ef950..63d3e00c 100644
--- a/Source/HBIOS/espsd.asm
+++ b/Source/HBIOS/espsd.asm
@@ -13,6 +13,7 @@
 ;
 ; TODO:
 ; - AVOID RESELECTING PRI/SEC ON EVERY I/O CALL
+; - REDUCE PUSH/POP CALLS IN GET/PUTBYTE, BLKREAD/WRITE
 ;
 ; NOTES:
 ;
@@ -34,7 +35,7 @@
 ;
 ;	XIN:	DATA READ FROM ESP32 PENDING
 ;	ERR:	ERROR ACTIVE
-;	DSW:	OLED DISPLAY ACTIVATION
+;	DSW:	OLED DISPLAY ACTIVATION SWITCH
 ;	CS1:	SD CARD 1 CHIP SELECT
 ;	CS0:	SD CARD 0 CHIP SELECT
 ;	CD1:	SD CARD 1 MEDIA PRESENT (CARD DETECT)
@@ -51,18 +52,53 @@
 ;	XIN:	UNUSED???
 ;	XOUT:	ACTIVATE WRITE TO ESP32
 ;
+; COMMAND/DATA EXCHANGES
+; ----------------------
+;  
+;   ->CMD_INIT1, <-STATUS
+;   ->CMD_INIT2, <-STATUS
+;   ->CMD_SEL1, <-STATUS
+;   ->CMD_SEL2, <-STATUS
+;   ->CMD_SETTRKSEC, ->[Track (byte), Sector (byte)], <-STATUS
+;   ->CMD_READ, <-[Sector Data (512 bytes)], <-STATUS
+;   ->CMD_WRITE, ->[Sector Data (512 bytes)], <-STATUS
+;   ->CMD_FORMAT, <-STATUS
+;   ->CMD_RESET
+;
+;   NEW/PROPOSED:
+;
+;   ->CMD_FWVER, <-[Version: Major (byte), Minor (byte)], <-STATUS
+;   ->CMD_SETLBA, ->[LBA value (4 bytes, MS first)], <-STATUS
+;   ->CMD_TYPE, <-[SD Card Type (1 byte)], <-STATUS
+;   ->CMD_CAP, <-[Sector Count (4 bytes, MS first)], <-STATUS
+;   ->CMD_CID, <-[CID Data (16 bytes), <-STATUS
+;   ->CMD_CSD, <-[CSD Data (16 bytes), <-STATUS
+;
+;   IF AN ERROR OCCURS IN ANY COMMAND THAT RETURNS DATA BEFORE THE
+;   STATUS BYTE, THEN DUMMY PADDING DATA MUST BE SENT BEFORE THE
+;   ERROR STATUS.
+;
 ESPSD_IO_STATUS		.EQU	0	; OFFSET OF STATUS PORT FROM BASE I/O ADDRESS
 ESPSD_IO_DATA		.EQU	1	; OFFSET OF DATA PORT FROM BASE I/O ADDRESS
 ;
-ESPSD_CMD_INIT0		.EQU	$80	; Initialize primary SD Card
+ESPSD_CMD_INIT0		.EQU	$80	; INITIALIZE PRIMARY SD CARD
 ESPSD_CMD_INIT1		.EQU	$81	; INITIALIZE SECONDARY SD CARD
 ESPSD_CMD_SEL0		.EQU	$82	; (RE)SELECT PRIMARY SD CARD
 ESPSD_CMD_SEL1		.EQU	$83	; (RE)SELECT SECONDARY SD CARD
-ESPSD_CMD_SETLBA	.EQU	$84	; SET LBA FOR SUBSEQUENT I/O
+ESPSD_CMD_SETTRKSEC	.EQU	$84	; SET TRACK/SECTOR FOR SUBSEQUENT I/O
 ESPSD_CMD_READ		.EQU	$85	; READ SECTOR FROM SELECTED SD CARD AT CURRENT LBA
 ESPSD_CMD_WRITE		.EQU	$86	; WRITE SECTOR TO SELECTED SD CARD AT CURRENT LBA
 ESPSD_CMD_FORMAT	.EQU	$87	; FORMAT SECTOR ON SELECTED SD CARD AT CURRENT LBA
 ESPSD_CMD_RESET		.EQU	$88	; RESET ESP32 MODULE
+ESPSD_CMD_FWVER		.EQU	$90	; REPORT ESP32 FIRMWARE VERSION
+ESPSD_CMD_SETLBA        .EQU	$91	; SET NEW CURRENT LBA (32-BIT)
+ESPSD_CMD_TYPE          .EQU	$92	; REPORT CARD TYPE OF SELECTED SD CARD
+ESPSD_CMD_CAP           .EQU	$93	; REPORT CAPACITY (SECTORS) OF SELECTED SD CARD
+ESPSD_CMD_CID           .EQU	$94	; REPORT CID DATA OF SELECTED SD CARD
+ESPSD_CMD_CSD           .EQU	$95	; REPORT CSD DATA OF SELECTED SD CARD
+;
+ESPSD_STAT_OK		.EQU	$00	; OPERATION COMPLETED OK
+ESPSD_STAT_ERR		.EQU	$1A	; OPERATION FAILED
 ;
 ; ESPSD DEVICE STATUS CODES
 ;
@@ -74,9 +110,7 @@ ESPSD_STNOTRDY		.EQU	-4
 ;
 ; IDE DEVICE CONFIGURATION
 ;
-ESPSD_CFGSIZ		.EQU	12		; SIZE OF CFG TBL ENTRIES
-;
-; PER DEVICE DATA OFFSETS
+; PER DEVICE DATA OFFSETS IN CFG BLOCK
 ;
 ESPSD_DEV		.EQU	0		; OFFSET OF DEVICE NUMBER (BYTE)
 ESPSD_ROLE		.EQU	1		; 0=PRIMARY, 1=SECONDARY
@@ -85,6 +119,8 @@ ESPSD_STAT		.EQU	3		; LAST STATUS (BYTE)
 ESPSD_MEDCAP		.EQU	4		; MEDIA CAPACITY (DWORD)
 ESPSD_LBA		.EQU	8		; OFFSET OF LBA (DWORD)
 ;
+ESPSD_CFGSIZ		.EQU	12		; SIZE OF CFG TBL ENTRIES
+;
 ESPSD_CFGTBL:
 ;
 #IF (ESPSDCNT >= 1)
@@ -275,12 +311,10 @@ ESPSD_DEFMED:
 ;
 ESPSD_READ:
 	CALL	HB_DSKREAD		; HOOK HBIOS DISK READ SUPERVISOR
-
 	;;;CALL	NEWLINE
 	;;;LD	A,'R'
 	;;;CALL	COUT
 	;;;CALL	PRTHEXWORDHL
-
 	LD	A,ESPSD_CMD_READ	; SETUP FOR BLOCK READ CMD
 	JP	ESPSD_IO		; CONTINUE TO GENERIC IO ROUTINE
 ;
@@ -288,12 +322,10 @@ ESPSD_READ:
 ;
 ESPSD_WRITE:
 	CALL	HB_DSKWRITE		; HOOK HBIOS DISK WRITE SUPERVISOR
-
 	;;;CALL	NEWLINE
 	;;;LD	A,'W'
 	;;;CALL	COUT
 	;;;CALL	PRTHEXWORDHL
-
 	LD	A,ESPSD_CMD_WRITE	; SETUP FOR BLOCK WRITE CMD
 	JP	ESPSD_IO		; CONTINUE TO GENERIC IO ROUTINE
 ;
@@ -526,7 +558,7 @@ ESPSD_RUNCMD:
 ; A 16-BIT LBA.
 ;
 ESPSD_SETLBA:
-	LD	E,ESPSD_CMD_SETLBA
+	LD	E,ESPSD_CMD_SETTRKSEC
 	CALL	ESPSD_CMD_SLOW
 	RET	NZ
 	LD	E,H
@@ -540,7 +572,7 @@ ESPSD_SETLBA:
 	LD	A,E			; RESULT TO ACCUM
 	OR	A			; SET FLAGS
 	RET	Z			; GOOD RETURN
-	LD	A,ESPSD_STIOERR	; CALL THIS AN IO ERROR
+	LD	A,ESPSD_STIOERR		; CALL THIS AN IO ERROR
 	OR	A
 	RET
 ;
@@ -555,22 +587,25 @@ ESPSD_BLKREAD:
 ESPSD_BLKREAD1:
 	PUSH	BC
 	CALL	ESPSD_GETBYTE_SLOW
+	POP	BC
 	RET	NZ
 	LD	(HL),E
 	INC	HL
+	PUSH	BC
 	CALL	ESPSD_GETBYTE_SLOW
+	POP	BC
 	RET	NZ
 	LD	(HL),E
 	INC	HL
-	POP	BC
 	DJNZ	ESPSD_BLKREAD1
 ;
 	CALL	ESPSD_GETBYTE_SLOW	; GET RESULT
 	RET	NZ			; HANDLE ERROR
 	LD	A,E			; RESULT TO ACCUM
+	;;;CALL	PRTHEXBYTE		; *DEBUG*
 	OR	A			; SET FLAGS
 	RET	Z			; GOOD RETURN
-	LD	A,ESPSD_STIOERR	; CALL THIS AN IO ERROR
+	LD	A,ESPSD_STIOERR		; CALL THIS AN IO ERROR
 	OR	A			; SET FLAGS
 	RET				; DONE
 ;
@@ -583,16 +618,18 @@ ESPSD_BLKWRITE:
 ;
 	LD	B,0			; LOOP COUNTER
 ESPSD_BLKWRITE1:
-	PUSH	BC
 	LD	E,(HL)
 	INC	HL
+	PUSH	BC
 	CALL	ESPSD_PUTBYTE_SLOW
+	POP	BC
 	RET	NZ
 	LD	E,(HL)
 	INC	HL
+	PUSH	BC
 	CALL	ESPSD_PUTBYTE_SLOW
-	RET	NZ
 	POP	BC
+	RET	NZ
 	DJNZ	ESPSD_BLKWRITE1
 ;
 	CALL	ESPSD_GETBYTE_SLOW	; GET RESULT
@@ -663,6 +700,7 @@ ESPSD_PUTBYTE2:
 ESPSD_PUTBYTE_SLOW:
 	PUSH	HL
 	LD	HL,50 * CPUMHZ		; CPU SPEED SCALED TIMEOUT
+	;;;LD	HL,0			; *DEBUG*
 ESPSD_PUTBYTE_SLOW1:
 	PUSH	HL
 	CALL	ESPSD_PUTBYTE
@@ -714,6 +752,7 @@ ESPSD_GETBYTE2:
 ESPSD_GETBYTE_SLOW:
 	PUSH	HL
 	LD	HL,50 * CPUMHZ		; CPU SPEED SCALED TIMEOUT
+	;;;LD	HL,0			; *DEBUG*
 ESPSD_GETBYTE_SLOW1:
 	PUSH	HL
 	CALL	ESPSD_GETBYTE
diff --git a/Source/ver.inc b/Source/ver.inc
index 01ff111e..b5ab0bb1 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,7 +2,7 @@
 #DEFINE	RMN	6
 #DEFINE	RUP	0
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.6.0-dev.18"
+#DEFINE BIOSVER	"3.6.0-dev.19"
 #define rmj	RMJ
 #define rmn	RMN
 #define rup	RUP
diff --git a/Source/ver.lib b/Source/ver.lib
index de03258f..1b841c39 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	6
 rup	equ	0
 rtp	equ	0
 biosver	macro
-	db	"3.6.0-dev.18"
+	db	"3.6.0-dev.19"
 	endm