*
** FLEX 9 DISK DRIVERS
*
* FOR SYS09BUG ON THE DIGILENT SPARTAN 3 STARTER BOARD
* WITH I/O MAPPED AT $XE000
* AND ROM MAPPED AT $XF000
* THE DIGILENT SPARTAN 3 STARTER BOARD HAS 1MBYTE OF SRAM
* THE FIRST 64K IS USED BY FLEX,
* THE SECOND 192K IS USED AS A ROM DISK
* THE REMAINING RAM IS USED FOR A RAM DISK
*
* These drivers should also work on the B5-X300 board
* although there is only enough room for the ROM Disk.
*
IMASK EQU $10 IRQ MASK CC
FMASK EQU $40 FIRQ MASK CC
TRPAGE EQU $0E PAGE $E000 DAT ADDRESS
DATREG EQU $FFF0 DAT REGISTERS
ORG $DE00
*
* DISK DRIVER JUMP TABLE LAST UPDATE: 22/12/2006
* Disk driver for RAM Disk.
*
* 14 SECTORS PER TRACK
* 16 * N TRACKS PER DISK
*
* ROM DISK OCCUPIES $10000 - $1E000, $20000 - $2E000, $30000 - $3E000
* RAM DISK OCCUPIES $40000 - $4E000 ... $F0000 - $FE000
* Track Buffer page mapped at $E000 - $EFFF
* TRPAGE = $0E = 14 x $1000 (4 K pages)
* LEAST SIGNIFICANT NYBBLE OF THE DAT IS INVERTED
* ON SWTPC ROM AT $XF000 AND IO AT $XE000
* APPEARS THROUGHOUT THE MEMORY SO MUST BE SKIPPED OVER
* WHEN USING RAM AS A RAMDISK.
* THE MSN OF THE TRACK MAPS INTO THE MSN OF THE DAT
* THE LSN OF THE TRACK NUMBER INDEXES INTO THE 4K RAM PAGE
* THE SECTOR MAPS INTO THE LSN OF THE DAT WHICH IS INVERTED
*
*
READ JMP READSC
WRITE JMP WRITSC
VERIFY JMP BUSY
RESTOR JMP RESTR1
DRIVE JMP DRVSEL
DRVRDY JMP CHKDRV
QUICK JMP CHKDRV
COLDDR JMP INITDR
WARMDR JMP WARMD1
SEEK JMP SEEKTS
*
* RAM SPACE
*
WRKDR FDB 0
WRKTR FDB 0,0,0,0
SECPTR FDB 0
TRKCNT FCB 0
SECCNT FCB 0
VERERR FCB 0
CCSAVE FCB 0
*
DRVBAS FCB $10 DRIVE 0
FCB $40 DRIVE 1
FCB $40 DRIVE 2
FCB $40 DRIVE 3
*
INITDR RTS
WARMD1 RTS
*
* Seek track and sector
* A holds track number (0-32)
* B holds sector number (1-14)
*
SEEKTS STA TRKCNT
STB SECCNT
ANDCC #$FE ; CLEAR CARRY
ORCC #$40 ; SET Z
RTS
*
* MAP RAM DISK INTO I/O SPACE
*
MAPIN TFR CC,A ; Save state of interrupt masks
STA CCSAVE
ORCC #FMASK+IMASK ; Mask interrupts while IO mapped out
LDA TRKCNT
LDU #DRVBAS ; Point to Drive base offset
LDB WRKDR ; Get working drive number
ADDA B,U ; Add Base offset into RAM
ANDA #$F0 ; Mask MSN
STA ,-S ; Save A on stack
*
LDA SECCNT
SUBA #1 ; Sectors 1 to 14 => 0 to 13
EORA #$0F ; Complement LSNybble
ANDA #$0F
*
ADDA ,S+ ; Add sector to LSN of Track and pop
STA DATREG+TRPAGE
*
LDA TRKCNT ; LSN of Track indexes into 4K page
ANDA #$0F
ADDA #TRPAGE*16
STA SECPTR
CLR SECPTR+1
LDU SECPTR
RTS
*
* MAP RAM DISK OUT OF MEMORY
*
MAPOUT LDA #TRPAGE ; Point to the I/O page
EORA #$0F ; Complement LSNybble
STA DATREG+TRPAGE ; map in I/O page
LDA CCSAVE ; restore interrupt masks
TFR A,CC
RTS
*
* READ DISK DRIVER
*
READSC LBSR SEEKTS ; SEEK TRACK & SECTOR
PSHS U,X
BSR MAPIN ; MAP RAM DISK INTO I/O SPACE
*
CLRB
READ3 LDA ,U+
STA ,X+ ; Move Sector to FCB
INCB
BNE READ3
*
BSR MAPOUT ; MAP RAM DISK OUT OF I/O SPACE
CLRB ; Z SET C CLEAR
PULS U,X,PC ; Restore registers and return
*
* WRITE DISK DRIVER
*
WRITSC BSR SEEKTS ; SEEK TRACK & SECTOR
PSHS U,X
BSR MAPIN ; MAP RAM DISK INTO I/O SPACE
*
CLRB
WRIT3 LDA ,X+ ; COPY FCB BLOCK TO RAM DISK
STA ,U+
INCB
BNE WRIT3
*
BSR MAPOUT ; MAP OUT RAM DISK
CLRB ; SET Z, CLEAR C
PULS U,X,PC ; Restore registers and return
*
* RESTORE DISK DRIVER (SEEK TRACK 00)
*
RESTR1 PSHS A
CLRA ; Track 0
LDAB #$01 ; Sector 1
LBSR SEEKTS
PULS A,PC
*
* CHECK FOR BUSY
* Doubles as VERIFY
*
BUSY CLRB Never busy
RTS
*
* DRIVE SELECT DISK DRIVER
*
DRVSEL PSHS X
LDA 3,X GET DRIVE # FROM FCB
CMPA #3
BLS DRVS2 IF > 3, SET IT TO 0
CLRA
DRVS2 BSR MXWT MOVE X TO WORKING TRK
LDB TRKCNT
STB 0,X SAVE TRACK
STA WRKDR SAVE DESIRED DRV AS WORKING DRV
BSR MXWT MOVE X TO WORKING TRK
LDA 0,X GET WORKING TRK ON DESIRED DRV
STA TRKCNT UPDATE 1771 TRACK REG
CLRB ; SET Z, CLEAR C
PULS X,PC
*
* MOVE INDEX REG TO POINT TO
* WORKING TRACK STORAGE
*
MXWT LDX #WRKTR POINT TO START OF STG
LDB WRKDR GET WORKING DRIVE
ABX
MXWT2 RTS
*
* CHECK DRIVE READY DISK DRIVER
*
CHKDRV LDA 3,X
CLRB ; CLEAR C, SET Z
RTS
END
