ORG     0100H

;------------------------------------------------------------
; SCSTEST_MENU_Z80.ASM
;
; Standalone Z80 NCR5380 SCSI read/write sector test
; No CP/M BDOS calls required for console I/O.
;
; Console:
;   CONSOLE_STATUS = 00H
;   CONSOLE_DATA   = 01H
;
; NCR5380:
;   Base I/O address = 40H
;
; Menu driven:
;   R = read selected CP/M 128-byte sector
;   W = write test pattern to selected CP/M sector, then read back
;   T = set track number, 4 hex digits
;   S = set sector number, 2 hex digits, 01..40H normally
;   D = dump last read sector buffer
;   Q = quit / return
;
; Disk geometry:
;   CP/M logical sector size = 128 bytes
;   SCSI physical sector     = 512 bytes
;   CP/M sectors per track   = 64
;   4 CP/M sectors per SCSI sector
;
; LBA = TRACK * 16 + ((SECTOR - 1) / 4)
;
; WARNING:
;   The W command writes a 128-byte test pattern into the selected
;   CP/M sector using read/modify/write of the containing 512-byte
;   SCSI physical sector.
;------------------------------------------------------------

CONSOLE_STATUS EQU  00H
CONSOLE_DATA   EQU  01H

DEFAULT_TRK    EQU  0000H
DEFAULT_SEC    EQU  0001H

NCRBASE EQU     48H		;Base port for all ports on board	

U17_SEL EQU     48H             ;U17 address selection port store for NCR5380
NCR_CS  EQU     4AH             ;Chip select for NRC5380 SCSI chip

ODR     EQU     NCRBASE+0
CSD     EQU     NCRBASE+0
ICR     EQU     NCRBASE+1
MR2     EQU     NCRBASE+2
TCR     EQU     NCRBASE+3
SER     EQU     NCRBASE+4
CSB     EQU     NCRBASE+4
BSR     EQU     NCRBASE+5
IDR     EQU     NCRBASE+6
RPI     EQU     NCRBASE+7

ICR_DBUS EQU    01H
ICR_ATN  EQU    02H
ICR_SEL  EQU    04H
ICR_BSY  EQU    08H
ICR_ACK  EQU    10H
ICR_RST  EQU    80H

PH_DATAOUT EQU  00H
PH_DATAIN  EQU  01H
PH_COMMAND EQU  02H
PH_STATUS  EQU  03H
PH_MSGOUT  EQU  06H
PH_MSGIN   EQU  07H

CSB_REQ EQU     20H
CSB_BSY EQU     40H

OURID   EQU     80H			;Controller SCSI ID  (ID 7)
TGTID   EQU     01H			;Assumes SCSI drive ID is  0

START:
        LD      SP,STACK
;       CALL    SCSI_INIT              ;<--- This was suggested by Chat GTP (made no difference)


        LD      HL,DEFAULT_TRK
        LD      (CURTRK),HL
        LD      HL,DEFAULT_SEC
        LD      (CURSEC),HL

        CALL    CRLF
        LD      HL,MSG_TITLE
        CALL    PSTRING

MAIN_MENU:
        CALL    SHOW_POSITION
        LD      HL,MSG_MENU
        CALL    PSTRING

        CALL    CONSOLE_INPUT_UPPER
        CALL    ECHO_CHAR
        CALL    CRLF

        CP      'R'
        JP      Z,DO_READ
        CP      'W'
        JP      Z,DO_WRITE
        CP      'T'
        JP      Z,SET_TRACK
        CP      'S'
        JP      Z,SET_SECTOR
        CP      'D'
        JP      Z,DO_DUMP
        CP      'Q'
        JP      Z,EXIT_PROGRAM

        LD      HL,MSG_BAD
        CALL    PSTRING
        JP      MAIN_MENU

EXIT_PROGRAM:
        LD      HL,MSG_EXIT
        CALL    PSTRING
        RET

DO_READ:
        CALL    MAKE_LBA
        CALL    SCSI_READ512
        OR      A
        JP      NZ,SCSI_ERROR
        CALL    COPY_FROM_SECBUF
        LD      HL,MSG_READOK
        CALL    PSTRING
        CALL    DUMP_DMABUF
        JP      MAIN_MENU

DO_WRITE:
        LD      HL,MSG_WARN1
        CALL    PSTRING
        CALL    CONSOLE_INPUT_UPPER
        CALL    ECHO_CHAR
        CALL    CRLF
        CP      'Y'
        JP      NZ,MAIN_MENU

        CALL    MAKE_LBA
        CALL    MAKE_PATTERN
        CALL    COPY_TO_SECBUF_RMW
        OR      A
        JP      NZ,SCSI_ERROR
        CALL    SCSI_WRITE512
        OR      A
        JP      NZ,SCSI_ERROR

        LD      HL,MSG_WRITEOK
        CALL    PSTRING
        CALL    SCSI_READ512
        OR      A
        JP      NZ,SCSI_ERROR
        CALL    COPY_FROM_SECBUF
        CALL    DUMP_DMABUF
        JP      MAIN_MENU

SET_TRACK:
        LD      HL,MSG_TRACK
        CALL    PSTRING
        CALL    READ_HEX4
        LD      (CURTRK),HL
        CALL    CRLF
        JP      MAIN_MENU

SET_SECTOR:
        LD      HL,MSG_SECTOR
        CALL    PSTRING
        CALL    READ_HEX2
        LD      L,A
        LD      H,0
        LD      (CURSEC),HL
        CALL    CRLF
        JP      MAIN_MENU

DO_DUMP:
        LD      HL,MSG_DUMP
        CALL    PSTRING
        CALL    DUMP_DMABUF
        JP      MAIN_MENU

SCSI_ERROR:
        LD      HL,MSG_SCSIERR
        CALL    PSTRING
        JP      MAIN_MENU

MAKE_LBA:
        LD      HL,(CURSEC)
        DEC     HL
        LD      A,L
        AND     03H
        CP      00H
        JR      NZ,MO1
        XOR     A
        LD      (SECOFFL),A
        LD      (SECOFFH),A
        JR      MOX
MO1:
        CP      01H
        JR      NZ,MO2
        LD      A,080H
        LD      (SECOFFL),A
        XOR     A
        LD      (SECOFFH),A
        JR      MOX
MO2:
        CP      02H
        JR      NZ,MO3
        XOR     A
        LD      (SECOFFL),A
        LD      A,01H
        LD      (SECOFFH),A
        JR      MOX
MO3:
        LD      A,080H
        LD      (SECOFFL),A
        LD      A,01H
        LD      (SECOFFH),A
MOX:
        LD      A,L             
        SRL     A
        SRL     A
        AND     0FH
        LD      E,A
        LD      D,0
        LD      HL,(CURTRK)
        ADD     HL,HL
        ADD     HL,HL
        ADD     HL,HL
        ADD     HL,HL
        ADD     HL,DE
        LD      A,L
        LD      (LBA0),A
        LD      A,H
        LD      (LBA1),A
        XOR     A
        LD      (LBA2),A
        RET

COPY_FROM_SECBUF:
        LD      HL,SECBUF
        LD      A,(SECOFFL)
        LD      E,A
        LD      A,(SECOFFH)
        LD      D,A
        ADD     HL,DE
        LD      DE,DMABUF
        LD      BC,128
        LDIR
        RET

COPY_TO_SECBUF_RMW:
        CALL    SCSI_READ512
        OR      A
        RET     NZ
        LD      HL,DMABUF
        LD      DE,SECBUF
        LD      A,(SECOFFL)
        LD      C,A
        LD      A,(SECOFFH)
        LD      B,A
        EX      DE,HL
        ADD     HL,BC
        EX      DE,HL
        LD      BC,128
        LDIR
        XOR     A
        RET

MAKE_PATTERN:
        LD      HL,DMABUF
        LD      B,128
        LD      A,00H
MP1:
        LD      (HL),A
        INC     A
        INC     HL
        DJNZ    MP1
        LD      HL,DMABUF
        LD      (HL),'S'
        INC     HL
        LD      (HL),'C'
        INC     HL
        LD      (HL),'S'
        INC     HL
        LD      (HL),'I'
        INC     HL
        LD      (HL),'-'
        INC     HL
        LD      (HL),'T'
        INC     HL
        LD      (HL),'E'
        INC     HL
        LD      (HL),'S'
        INC     HL
        LD      (HL),'T'
        RET

SCSI_READ512:
        CALL    BUILD_READ_CDB
        LD	A,'@'           ;;;;;;;;;;;;;;;;
 	CALL	ZCO
        CALL    SCSI_SELECT
        RET     NZ

	LD	A,'#'           ;;;;;;;;;;;;;;;;
 	CALL	ZCO
        LD      HL,CDB
        LD      B,6
        CALL    SCSI_SEND_CMD
        RET     NZ

	LD	A,'$'           ;;;;;;;;;;;;;;;;
 	CALL	ZCO
        LD      HL,SECBUF
        LD      DE,512
        CALL    SCSI_RECV_DATA
        RET     NZ

	LD	A,'%'           ;;;;;;;;;;;;;;;;
 	CALL	ZCO
        CALL    SCSI_GET_STATUS
        RET

SCSI_WRITE512:
        CALL    BUILD_WRITE_CDB
        CALL    SCSI_SELECT
        RET     NZ
        LD      HL,CDB
        LD      B,6
        CALL    SCSI_SEND_CMD
        RET     NZ
        LD      HL,SECBUF
        LD      DE,512
        CALL    SCSI_SEND_DATA
        RET     NZ
        CALL    SCSI_GET_STATUS
        RET

BUILD_READ_CDB:
        LD      HL,CDB
        LD      (HL),08H
        INC     HL
        LD      A,(LBA2)
        AND     1FH
        LD      (HL),A
        INC     HL
        LD      A,(LBA1)
        LD      (HL),A
        INC     HL
        LD      A,(LBA0)
        LD      (HL),A
        INC     HL
        LD      (HL),01H
        INC     HL
        LD      (HL),00H
        RET

BUILD_WRITE_CDB:
        LD      HL,CDB
        LD      (HL),0AH
        INC     HL
        LD      A,(LBA2)
        AND     1FH
        LD      (HL),A
        INC     HL
        LD      A,(LBA1)
        LD      (HL),A
        INC     HL
        LD      A,(LBA0)
        LD      (HL),A
        INC     HL
        LD      (HL),01H
        INC     HL
        LD      (HL),00H
        RET

SCSI_SELECT:
        XOR     A
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<       
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;



;;;;;;; OUT     (TCR),A                 ;<<<<<<<<<<<<  
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;
                                        ;Store NRC port address select  

;;;;;;; OUT     (MR2),A                 ;<<<<<<<<<<<<  
        PUSH    AF                      ;
        LD      A,MR2                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

SELWAIT:
;;;;;;  IN      A,(CSB)			;<<<<<<<<<<<<<<
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        AND     CSB_BSY
        JR      NZ,SELWAIT
        
        LD      A,OURID+TGTID
;;;;;;; OUT     (ODR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ODR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A              ;
 
        LD      A,ICR_DBUS+ICR_SEL
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A              ;

         CALL    DELAY

SELBUSY:
;;;;;;; IN      A,(CSB)
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)
        AND     CSB_BSY
        JR      Z,SELBUSY

        XOR     A
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;
                                        ;Store NRC port address select  
        XOR     A
        RET

SCSI_SEND_CMD:
        LD      A,PH_COMMAND
;;;;;;; OUT     (TCR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

SCMD1:
        LD      A,(HL)
        CALL    SCSI_SEND_BYTE
        RET     NZ
        INC     HL
        DJNZ    SCMD1
        XOR     A
        RET

SCSI_SEND_DATA:
;;;;;;; OUT     (TCR),A                 ;<<<<<<<<<<<<
        LD      A,PH_DATAOUT            ;<---- Suggested by Chat GPT -------------
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A              ;

SDO1:
        LD      A,D
        OR      E
        JR      Z,SDO_DONE
        LD      A,(HL)
        CALL    SCSI_SEND_BYTE
        RET     NZ
        INC     HL
        DEC     DE
        JP      SDO1
SDO_DONE:
        XOR     A
        RET

SCSI_RECV_DATA:
        LD      A,PH_DATAIN
;;;;;;; OUT     (TCR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

SDI1:
        LD      A,D
        OR      E
        JR      Z,SDI_DONE
        CALL    SCSI_RECV_BYTE
        LD      (HL),A
        INC     HL
        DEC     DE
        JP      SDI1
SDI_DONE:
        XOR     A
        RET

SCSI_SEND_BYTE:
;;;;;;; OUT     (ODR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ODR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

WSREQ1:
;;;;;;; IN      A,(CSB)                 ;<<<<<<<<<<<< 
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        AND     CSB_REQ
        JR      Z,WSREQ1
        LD      A,ICR_DBUS
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

        LD      A,ICR_DBUS+ICR_ACK
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

WSREQ0:
;;;;;;; IN      A,(CSB)                 ;<<<<<<<<<<<< 
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        AND     CSB_REQ
        JR      NZ,WSREQ0
        XOR     A
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

        XOR     A
        RET

SCSI_RECV_BYTE:
WRREQ1:
;;;;;;; IN      A,(CSB)                 ;<<<<<<<<<<<< 
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        AND     CSB_REQ
        JR      Z,WRREQ1
;;;;;;; IN      A,(CSD)                 ;<<<<<<<<<<<< 
        LD      A,CSD                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        PUSH    AF
        LD      A,ICR_ACK
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

WRREQ0:
;;;;;;; IN      A,(CSB)                 ;<<<<<<<<<<<< 
        LD      A,CSB                   ;Store NRC port address select
        OUT     (U17_SEL),A
        IN      A,(NCR_CS)

        AND     CSB_REQ
        JR      NZ,WRREQ0
        XOR     A
;;;;;;; OUT     (ICR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,ICR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

        POP     AF
        RET

SCSI_GET_STATUS:
        LD      A,PH_STATUS
;;;;;;; OUT     (TCR),A                 ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

        CALL    SCSI_RECV_BYTE
        LD      (SCSISTAT),A
        LD      A,PH_MSGIN
;;;;;;; OUT     (TCR),A                  ;<<<<<<<<<<<<
        PUSH    AF                      ;
        LD      A,TCR                   ;Store NRC port address select  
        OUT     (U17_SEL),A             ;
        POP     AF                      ;
        OUT     (NCR_CS),A             ;

        CALL    SCSI_RECV_BYTE
        LD      (SCSIMSG),A
        LD      A,(SCSISTAT)
        OR      A
        JR      Z,SGOK
        LD      A,1
        RET
SGOK:
        XOR     A
        RET



SCSI_INIT:                                      ;Chat GTP code additions
        XOR     A
        CALL    NCR_OUT_ICR
        CALL    NCR_OUT_TCR
        CALL    NCR_OUT_MR2
        CALL    NCR_OUT_SER

        LD      A,ICR_RST
        CALL    NCR_OUT_ICR
        CALL    LONG_DELAY

        XOR     A
        CALL    NCR_OUT_ICR

        CALL    LONG_DELAY
        CALL    LONG_DELAY
        RET

NCR_OUT_ICR:
        PUSH    AF
        LD      A,ICR
        OUT     (U17_SEL),A
        POP     AF
        OUT     (NCR_CS),A
        RET

NCR_OUT_TCR:
        PUSH    AF
        LD      A,TCR
        OUT     (U17_SEL),A
        POP     AF
        OUT     (NCR_CS),A
        RET

NCR_OUT_MR2:
        PUSH    AF
        LD      A,MR2
        OUT     (U17_SEL),A
        POP     AF
        OUT     (NCR_CS),A
        RET

NCR_OUT_SER:
        PUSH    AF
        LD      A,SER
        OUT     (U17_SEL),A
        POP     AF
        OUT     (NCR_CS),A
        RET

LONG_DELAY:
        LD      DE,0010H
LDLY1:  LD      BC,0FFFFH
LDLY2:  DEC     BC
        LD      A,B
        OR      C
        JR      NZ,LDLY2
        DEC     DE
        LD      A,D
        OR      E
        JR      NZ,LDLY1
        RET

;----------------------------------- Support Routines -------------------------

ZCI:
        IN      A,(CONSOLE_STATUS)
        AND     02H
        JR      Z,ZCI
        IN      A,(CONSOLE_DATA)
        AND     7FH
        RET

ZCO:	PUSH	AF			;Note this is different from typical Monitor ZCO
ZCO1:   IN      A,(CONSOLE_STATUS)	;where the character in in [C]
        AND     04H
        JR      Z,ZCO1
	POP	AF
        OUT     (CONSOLE_DATA),A        ;<<<<<<<<<<<<
                                        ;Store NRC port address select  

        RET


ZCSTS:
        IN      A,(CONSOLE_STATUS)
        AND     02H
        JP      Z,NOCHAR
GOT_CHAR:
        XOR     A
        DEC     A
        RET
NOCHAR:
        XOR     A
        RET

CONSOLE_INPUT_UPPER:
        CALL    ZCI
        CP      'a'
        RET     C
        CP      'z'+1
        RET     NC
        SUB     20H
        RET

ECHO_CHAR:
        CALL    ZCO
        RET

PSTRING:
        LD      A,(HL)
        CP      '$'
        RET     Z
        CALL    ZCO
        INC     HL
        JR      PSTRING

CRLF:
	PUSH	AF
        LD      A,13
        CALL    ZCO
        LD      A,10
        CALL    ZCO
        POP	AF
        RET

SPACE:
        LD      A,' '
        CALL    ZCO
        RET

READ_HEX4:
        LD      HL,0
        LD      B,4
RH4_1:
        CALL    READ_HEX_NIBBLE
        ADD     HL,HL
        ADD     HL,HL
        ADD     HL,HL
        ADD     HL,HL
        LD      E,A
        LD      D,0
        ADD     HL,DE
        DJNZ    RH4_1
        RET

READ_HEX2:
        CALL    READ_HEX_NIBBLE
        RLCA
        RLCA
        RLCA
        RLCA
        LD      B,A
        CALL    READ_HEX_NIBBLE
        OR      B
        RET

READ_HEX_NIBBLE:
        CALL    CONSOLE_INPUT_UPPER
        CALL    ECHO_CHAR
        CP      '0'
        JR      C,READ_HEX_NIBBLE
        CP      '9'+1
        JR      C,RHN_DIGIT
        CP      'A'
        JR      C,READ_HEX_NIBBLE
        CP      'F'+1
        JR      NC,READ_HEX_NIBBLE
        SUB     'A'-10
        RET
RHN_DIGIT:
        SUB     '0'
        RET

HEXOUT:
        PUSH    AF
        RRCA
        RRCA
        RRCA
        RRCA
        CALL    HEXNIB
        POP     AF
        CALL    HEXNIB
        RET

HEXNIB:
        AND     0FH
        CP      10
        JR      C,HEXDIG
        ADD     A,7
HEXDIG:
        ADD     A,'0'
        CALL    ZCO
        RET

PRINT_HL_HEX:
        LD      A,H
        CALL    HEXOUT
        LD      A,L
        CALL    HEXOUT
        RET

PRINT_A_HEX:
        CALL    HEXOUT
        RET

SHOW_POSITION:
        CALL    CRLF
        LD      HL,MSG_POS1
        CALL    PSTRING
        LD      HL,(CURTRK)
        CALL    PRINT_HL_HEX
        LD      HL,MSG_POS2
        CALL    PSTRING
        LD      HL,(CURSEC)
        LD      A,L
        CALL    PRINT_A_HEX
        CALL    CRLF
        RET

DUMP_DMABUF:
        LD      HL,DMABUF
        LD      B,8
DUMPLINE:
        PUSH    BC
        LD      B,16
DUMPBYTE:
        LD      A,(HL)
        CALL    HEXOUT
        CALL    SPACE
        INC     HL
        DJNZ    DUMPBYTE
        CALL    CRLF
        POP     BC
        DJNZ    DUMPLINE
        RET

DELAY:
        LD      BC,0020H
DLY1:
        DEC     BC
        LD      A,B
        OR      C
        JR      NZ,DLY1
        RET

MSG_TITLE:
        DB      'NCR5380 SCSI SECTOR TEST - DIRECT CONSOLE I/O (V0.1A) ',13,10,'$'
MSG_MENU:
        DB      13,10
        DB      'R = Read selected sector',13,10
        DB      'W = Write test pattern to selected sector',13,10
        DB      'T = Set track, 4 hex digits',13,10
        DB      'S = Set sector, 2 hex digits',13,10
        DB      'D = Dump last buffer',13,10
        DB      'Q = Quit',13,10
        DB      'Choice: $'
MSG_POS1:
        DB      'Current Track=$'
MSG_POS2:
        DB      ' Sector=$'
MSG_TRACK:
        DB      'Enter track as 4 hex digits: $'
MSG_SECTOR:
        DB      'Enter sector as 2 hex digits, 01-40H: $'
MSG_BAD:
        DB      'Unknown command',13,10,'$'
MSG_WARN1:
        DB      'WRITE WILL MODIFY THE DISK. Type Y to continue: $'
MSG_READOK:
        DB      'READ OK - 128 byte sector dump:',13,10,'$'
MSG_WRITEOK:
        DB      'WRITE OK - readback follows:',13,10,'$'
MSG_DUMP:
        DB      'Last 128 byte buffer:',13,10,'$'
MSG_SCSIERR:
        DB      'SCSI ERROR',13,10,'$'
MSG_EXIT:
        DB      'Exiting.',13,10,'$'


CURTRK: DW      0
CURSEC: DW      1
LBA0:   DB      0
LBA1:   DB      0
LBA2:   DB      0
SECOFFL: DB     0
SECOFFH: DB     0
CDB:        DS  6
SCSISTAT:   DB  0
SCSIMSG:    DB  0
DMABUF:     DS  128
SECBUF:     DS  512
            DS  256
STACK:

        END     START