mirror of
https://github.com/tjboldt/ProDOS-ROM-Drive.git
synced 2024-11-24 00:31:12 +00:00
214 lines
8.9 KiB
Plaintext
214 lines
8.9 KiB
Plaintext
ca65 V2.18 - N/A
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Main file : Firmware.asm
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Current file: Firmware.asm
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000000r 1 ;i/o ports to write to
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000000r 1 writeLatchHigh = $C081
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000000r 1 writeLatchLow = $C080
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000000r 1
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000000r 1 ;temp variables becasue 6502 only has 3 registers
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000000r 1 highLatch = $F8
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000000r 1 lowLatch = $F9
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000000r 1 tempY = $FE
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000000r 1 blockHalfCounter = $FF
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000000r 1
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000000r 1 ;ProDOS defines
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000000r 1 command = $42 ;ProDOS command
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000000r 1 unit = $43 ;7=drive 6-4=slot 3-0=not used
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000000r 1 buflo = $44 ;low address of buffer
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000000r 1 bufhi = $45 ;hi address of buffer
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000000r 1 blklo = $46 ;low block
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000000r 1 blkhi = $47 ;hi block
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000000r 1 ioerr = $27 ;I/O error code
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000000r 1 nodev = $28 ;no device connected
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000000r 1 wperr = $2B ;write protect error
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000000r 1
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000000r 1 ;for relocatable code, address to jump to instead of JSR absolute + RTS
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000000r 1 jumpAddressLo = $FA
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000000r 1 jumpAddressHi = $FB
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000000r 1 ioAddressLo = $FC
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000000r 1 ioAddressHi = $FD
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000000r 1 knownRts = $FF58
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000000r 1
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000000r 1 .org $C700
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00C700 1 ;code is relocatable
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00C700 1 ; but set to $c700 for
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00C700 1 ; readability
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00C700 1
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00C700 1 ;ID bytes for booting and drive detection
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00C700 1 E0 20 cpx #$20 ;ID bytes for ProDOS and the
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00C702 1 A0 00 ldy #$00 ; Apple Autostart ROM
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00C704 1 E0 03 cpx #$03 ;
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00C706 1 E0 3C cpx #$3C ;this one for older II's
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00C708 1
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00C708 1 ;zero out block numbers and buffer address
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00C708 1 84 44 sty buflo
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00C70A 1 84 46 sty blklo
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00C70C 1 84 47 sty blkhi
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00C70E 1 C8 iny ;set command = 1 for read block
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00C70F 1 84 42 sty command
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00C711 1 84 FA sty jumpAddressLo ;$01 of $0801 where boot code starts
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00C713 1 20 58 FF jsr knownRts ;jump to known RTS to get our address from the stack
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00C716 1 BA tsx
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00C717 1 BD 00 01 lda $0100,x ;this for example would be $C7 in slot 7
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00C71A 1 85 45 sta bufhi ;keep the slot here
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00C71C 1 0A asl
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00C71D 1 0A asl
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00C71E 1 0A asl
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00C71F 1 0A asl
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00C720 1 AA tax
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00C721 1
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00C721 1 ;display copyright message
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00C721 1 A0 C5 ldy #<text
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00C723 1 drawtxt:
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00C723 1 B1 44 lda (buflo),y
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00C725 1 F0 06 beq boot
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00C727 1 99 0B 07 sta $07D0-<text,y ;put text on last line
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00C72A 1 C8 iny
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00C72B 1 D0 F6 bne drawtxt
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00C72D 1
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00C72D 1 ;load block 0000 at $0800
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00C72D 1 boot:
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00C72D 1 A9 08 lda #$08
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00C72F 1 85 45 sta bufhi
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00C731 1 85 FB sta jumpAddressHi
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00C733 1 86 43 stx unit
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00C735 1 D0 08 bne start
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00C737 1 ;This is the ProDOS entry point for this card
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00C737 1 entry:
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00C737 1 A9 58 lda #<knownRts
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00C739 1 85 FA sta jumpAddressLo
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00C73B 1 A9 FF lda #>knownRts
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00C73D 1 85 FB sta jumpAddressHi
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00C73F 1 start:
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00C73F 1 A9 C0 lda #$C0
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00C741 1 85 FD sta ioAddressHi
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00C743 1 20 58 FF jsr knownRts
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00C746 1 BA tsx
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00C747 1 BD 00 01 lda $0100,x
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00C74A 1 0A asl a
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00C74B 1 0A asl a
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00C74C 1 0A asl a
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00C74D 1 0A asl a
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00C74E 1 AA tax
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00C74F 1 E4 43 cpx unit ;make sure same as ProDOS
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00C751 1 F0 04 beq docmd ;yep, do command
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00C753 1 38 sec ;nope, set device not connected
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00C754 1 A9 28 lda #nodev
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00C756 1 60 rts ;go back to ProDOS
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00C757 1
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00C757 1 docmd:
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00C757 1 A5 42 lda command
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00C759 1 F0 08 beq getstat ;command 0 is GetStatus
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00C75B 1 C9 01 cmp #$01
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00C75D 1 F0 0C beq readblk ;command 1 is ReadBlock
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00C75F 1 38 sec ;Format/Write not permitted
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00C760 1 A9 2B lda #wperr ;write protect error
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00C762 1 60 rts ;go back to ProDOS
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00C763 1
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00C763 1 getstat:
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00C763 1 18 clc ;send back status
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00C764 1 A9 00 lda #$00 ;good status
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00C766 1 A2 00 ldx #$00 ;1024 blocks
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00C768 1 A0 04 ldy #$04 ;
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00C76A 1 60 rts
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00C76B 1
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00C76B 1 readblk:
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00C76B 1 A5 47 lda blkhi ;get hi block
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00C76D 1 0A asl a ;shift up to top 3 bits
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00C76E 1 0A asl a ;since that's all the high
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00C76F 1 0A asl a ;blocks we can handle
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00C770 1 0A asl a ;
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00C771 1 0A asl a ;
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00C772 1 85 F8 sta highLatch ;save it in scratch ram 0
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00C774 1 ;so we can stuff it in the
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00C774 1 ;high latch later
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00C774 1 A5 46 lda blklo ;get low block
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00C776 1 4A lsr a ;shift so we get the top 5
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00C777 1 4A lsr a ;bits - this also goes in
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00C778 1 4A lsr a ;the high latch
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00C779 1 05 F8 ora highLatch ;add it to those top 3 bits
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00C77B 1 85 F8 sta highLatch ;save it back in scratch ram
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00C77D 1 A5 46 lda blklo ;get low block
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00C77F 1 0A asl a ;shift it to top 3 bits
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00C780 1 0A asl a ;
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00C781 1 0A asl a ;
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00C782 1 0A asl a ;
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00C783 1 0A asl a ;
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00C784 1 85 F9 sta lowLatch
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00C786 1 A9 02 lda #$02
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00C788 1 85 FF sta blockHalfCounter
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00C78A 1
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00C78A 1 ;This gets 256 bytes from the ROM card
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00C78A 1
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00C78A 1 read256:
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00C78A 1 A0 00 ldy #$00
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00C78C 1 A5 F8 lda highLatch ;get high latch value
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00C78E 1 9D 81 C0 sta writeLatchHigh,x ;set high latch for card
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00C791 1 loop256:
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00C791 1 A5 F9 lda lowLatch
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00C793 1 9D 80 C0 sta writeLatchLow,x
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00C796 1 8A txa
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00C797 1 09 80 ora #$80
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00C799 1 85 FC sta ioAddressLo
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00C79B 1 loop16:
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00C79B 1 84 FE sty tempY
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00C79D 1 A0 00 ldy #$00
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00C79F 1 B1 FC lda (ioAddressLo),y
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00C7A1 1 A4 FE ldy tempY
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00C7A3 1 91 44 sta (buflo),y
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00C7A5 1 C8 iny
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00C7A6 1 E6 FC inc ioAddressLo
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00C7A8 1 A5 FC lda ioAddressLo
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00C7AA 1 29 0F and #$0F
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00C7AC 1 D0 ED bne loop16
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00C7AE 1 E6 F9 inc lowLatch
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00C7B0 1 C0 00 cpy #$00
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00C7B2 1 D0 DD bne loop256
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00C7B4 1 C6 FF dec blockHalfCounter
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00C7B6 1 D0 08 bne readnext256
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00C7B8 1 C6 45 dec bufhi
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00C7BA 1 18 clc ;clear error code for success
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00C7BB 1 A9 00 lda #$00
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00C7BD 1 6C FA 00 jmp (jumpAddressLo)
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00C7C0 1
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00C7C0 1 readnext256:
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00C7C0 1 E6 45 inc bufhi
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00C7C2 1 18 clc
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00C7C3 1 90 C5 bcc read256
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00C7C5 1
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00C7C5 1 ;macro for string with high-bit set
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00C7C5 1 .macro aschi str
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00C7C5 1 .repeat .strlen (str), c
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00C7C5 1 .byte .strat (str, c) | $80
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00C7C5 1 .endrep
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00C7C5 1 .endmacro
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00C7C5 1
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00C7C5 1 D2 CF CD AD text: aschi "ROM-Drive (c)1998-2021 Terence J. Boldt"
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00C7C9 1 C4 F2 E9 F6
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00C7CD 1 E5 A0 A8 E3
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00C7D1 1 A9 B1 B9 B9
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00C7D5 1 B8 AD B2 B0
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00C7D9 1 B2 B1 A0 D4
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00C7DD 1 E5 F2 E5 EE
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00C7E1 1 E3 E5 A0 CA
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00C7E5 1 AE A0 C2 EF
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00C7E9 1 EC E4 F4
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00C7EC 1 end:
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00C7EC 1 00 .byte 0
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00C7ED 1
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00C7ED 1 ; These bytes need to be at the top of the 256 byte firmware as ProDOS
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00C7ED 1 ; uses these to find the entry point and drive capabilities
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00C7ED 1
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00C7ED 1 00 00 00 00 .repeat 251-<end
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00C7F1 1 00 00 00 00
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00C7F5 1 00 00 00 00
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00C7F9 1 00 00 00
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00C7FC 1 .byte 0
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00C7FC 1 .endrepeat
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00C7FC 1
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00C7FC 1 00 00 .byte 0,0 ;0000 blocks = check status
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00C7FE 1 03 .byte 3 ;bit 0=read 1=status
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00C7FF 1 37 .byte <entry ;low byte of entry
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00C7FF 1
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