ca65 V2.18 - N/A
Main file   : Firmware.asm
Current file: Firmware.asm

000000r 1                   writeLatchHigh = $C081
000000r 1                   writeLatchLow = $C080
000000r 1               
000000r 1               ;temp variables becasue 6502 only has 3 registers
000000r 1               	highLatch = $F8
000000r 1               	lowLatch = $F9
000000r 1               	tempY = $FE
000000r 1               	blockHalfCounter = $FF
000000r 1               
000000r 1               ;ProDOS defines
000000r 1                   command = $42   ;ProDOS command
000000r 1                   unit  = $43     ;7=drive 6-4=slot 3-0=not used
000000r 1                   buflo = $44     ;low address of buffer
000000r 1                   bufhi = $45     ;hi address of buffer
000000r 1                   blklo = $46     ;low block
000000r 1                   blkhi = $47     ;hi block
000000r 1                   ioerr = $27     ;I/O error code
000000r 1                   nodev = $28     ;no device connected
000000r 1                   wperr = $2B     ;write protect error
000000r 1               
000000r 1               ;for relocatable code, address to jump to instead of JSR absolute + RTS
000000r 1               	jumpAddressLo = $FA
000000r 1               	jumpAddressHi = $FB
000000r 1               	ioAddressLo   = $FC
000000r 1               	ioAddressHi   = $FD
000000r 1               	knownRts      = $FF58
000000r 1               
000000r 1               	.org     $C700
00C700  1               			;code is relocatable
00C700  1               			; but set to $c700 for
00C700  1               			; readability
00C700  1               
00C700  1               ;ID bytes for booting and drive detection
00C700  1  E0 20        	cpx     #$20    ;ID bytes for ProDOS and the
00C702  1  E0 00        	cpx     #$00    ; Apple Autostart ROM
00C704  1  E0 03        	cpx     #$03    ;
00C706  1  E0 3C        	cpx     #$3C    ;this one for older II's
00C708  1               
00C708  1               ;zero out block numbers and buffer address
00C708  1  84 44        	sty		buflo
00C70A  1  84 46        	sty 	blklo
00C70C  1  84 47        	sty		blkhi
00C70E  1  C8           	iny				;set command = 1 for read block
00C70F  1  84 42        	sty		command
00C711  1  84 FA        	sty		jumpAddressLo ;$01 of $0801 where boot code starts
00C713  1  20 58 FF     	jsr 	knownRts ;jump to known RTS to get our address from the stack
00C716  1  BA           	tsx
00C717  1  BD 00 01         lda     $0100,x ;this for example would be $C7 in slot 7
00C71A  1  85 45            sta     bufhi   ;keep the slot here
00C71C  1  0A               asl
00C71D  1  0A               asl
00C71E  1  0A               asl
00C71F  1  0A               asl
00C720  1  AA               tax
00C721  1               
00C721  1               ;display copyright message
00C721  1  A0 C1            ldy     #<text
00C723  1  B1 44        drawtxt: lda     (buflo),y
00C725  1  99 D0 07     	sta     $07D0,y ;put text on last line
00C728  1  C8           	iny
00C729  1  D0 F8        	bne     drawtxt
00C72B  1               
00C72B  1               ;load block 0000 at $0800
00C72B  1  A9 08        	lda     #$08
00C72D  1  85 45        	sta     bufhi
00C72F  1  85 FB        	sta     jumpAddressHi
00C731  1  86 43        	stx     unit
00C733  1  D0 08        	bne     start
00C735  1               ;This is the ProDOS entry point for this card
00C735  1               entry:
00C735  1  A9 58        	lda     #<knownRts
00C737  1  85 FA        	sta     jumpAddressLo
00C739  1  A9 FF        	lda     #>knownRts
00C73B  1  85 FB        	sta     jumpAddressHi
00C73D  1               start:
00C73D  1  A9 C0        	lda     #$C0
00C73F  1  85 FD        	sta     ioAddressHi
00C741  1  20 58 FF     	jsr     knownRts
00C744  1  BA           	tsx
00C745  1  BD 00 01     	lda     $0100,x
00C748  1  0A           	asl     a
00C749  1  0A           	asl     a
00C74A  1  0A           	asl     a
00C74B  1  0A           	asl     a
00C74C  1  AA           	tax
00C74D  1  E4 43        	cpx     unit	;make sure same as ProDOS
00C74F  1  F0 04        	beq     docmd	;yep, do command
00C751  1  38           	sec				;nope, set device not connected
00C752  1  A9 28        	lda     #nodev
00C754  1  60           	rts             ;go back to ProDOS
00C755  1               
00C755  1               docmd:
00C755  1  A5 42        	lda command
00C757  1  F0 08        	beq     getstat ;command 0 is GetStatus
00C759  1  C9 01        	cmp     #$01
00C75B  1  F0 0C        	beq     readblk ;command 1 is ReadBlock
00C75D  1  38           	sec             ;Format/Write not permitted
00C75E  1  A9 2B        	lda     #wperr  ;write protect error
00C760  1  60           	rts             ;go back to ProDOS
00C761  1               
00C761  1               getstat:
00C761  1  18           	clc             ;send back status
00C762  1  A9 00        	lda     #$00    ;good status
00C764  1  A2 00        	ldx     #$00    ;1024 blocks
00C766  1  A0 04        	ldy     #$04    ;
00C768  1  60           	rts
00C769  1               
00C769  1               readblk:
00C769  1  A5 47        	lda     blkhi	;get hi block
00C76B  1  0A           	asl     a       ;shift up to top 3 bits
00C76C  1  0A           	asl     a       ;since that's all the high
00C76D  1  0A           	asl     a       ;blocks we can handle
00C76E  1  0A           	asl     a       ;
00C76F  1  0A           	asl     a       ;
00C770  1  85 F8        	sta     highLatch   ;save it in scratch ram 0
00C772  1               			;so we can stuff it in the
00C772  1               			;high latch later
00C772  1  A5 46        	lda     blklo   ;get low block
00C774  1  4A           	lsr     a       ;shift so we get the top 5
00C775  1  4A           	lsr     a       ;bits - this also goes in
00C776  1  4A           	lsr     a       ;the high latch
00C777  1  05 F8        	ora     highLatch ;add it to those top 3 bits
00C779  1  85 F8        	sta     highLatch ;save it back in scratch ram
00C77B  1  A5 46        	lda     blklo   ;get low block
00C77D  1  0A           	asl     a       ;shift it to top 3 bits
00C77E  1  0A           	asl     a       ;
00C77F  1  0A           	asl     a       ;
00C780  1  0A           	asl     a       ;
00C781  1  0A           	asl     a       ;
00C782  1  85 F9        	sta     lowLatch
00C784  1  A9 02        	lda     #$02
00C786  1  85 FF        	sta     blockHalfCounter
00C788  1               
00C788  1               ;This gets 256 bytes from the ROM card
00C788  1               
00C788  1               read256:
00C788  1  A0 00        	ldy     #$00
00C78A  1  A5 F8        	lda     highLatch	;get high latch value
00C78C  1  9D 81 C0     	sta     writeLatchHigh,x	;set high latch for card
00C78F  1               loop256:
00C78F  1  A5 F9        	lda     lowLatch
00C791  1  9D 80 C0     	sta     writeLatchLow,x
00C794  1  8A           	txa
00C795  1  09 80        	ora     #$80
00C797  1  85 FC        	sta     ioAddressLo
00C799  1               loop16:
00C799  1  84 FE        	sty     tempY
00C79B  1  A0 00        	ldy     #$00
00C79D  1  B1 FC        	lda     (ioAddressLo),y
00C79F  1  A4 FE        	ldy     tempY
00C7A1  1  91 44        	sta     (buflo),y
00C7A3  1  C8           	iny
00C7A4  1  E6 FC        	inc     ioAddressLo
00C7A6  1  A5 FC        	lda     ioAddressLo
00C7A8  1  29 0F        	and     #$0F
00C7AA  1  D0 ED        	bne     loop16
00C7AC  1  E6 F9        	inc     lowLatch
00C7AE  1  C0 00        	cpy     #$00
00C7B0  1  D0 DD        	bne     loop256
00C7B2  1  C6 FF        	dec     blockHalfCounter
00C7B4  1  D0 06        	bne     readnext256
00C7B6  1  C6 45        	dec     bufhi
00C7B8  1  18           	clc             ;clear error code for success
00C7B9  1  A9 00        	lda     #$00
00C7BB  1  60           	rts             ;return to ProDOS
00C7BC  1               
00C7BC  1               readnext256:
00C7BC  1  E6 45        	inc     bufhi
00C7BE  1  18               clc
00C7BF  1  90 C7            bcc     read256
00C7C1  1               
00C7C1  1               ;macro for string with high-bit set
00C7C1  1               .macro aschi str
00C7C1  1               .repeat .strlen (str), c
00C7C1  1               .byte .strat (str, c) | $80
00C7C1  1               .endrep
00C7C1  1               .endmacro
00C7C1  1               
00C7C1  1  D2 CF CD AD  text:   aschi      "ROM-Drive (c)1998-2021 Terence J. Boldt"
00C7C5  1  C4 F2 E9 F6  
00C7C9  1  E5 A0 A8 E3  
00C7E8  1               end:
00C7E8  1  00           	.byte	 0
00C7E9  1               
00C7E9  1               ; These bytes need to be at the top of the 256 byte firmware as ProDOS
00C7E9  1               ; uses these to find the entry point and drive capabilities
00C7E9  1               
00C7E9  1  00 00 00 00  .repeat	251-<end
00C7ED  1  00 00 00 00  
00C7F1  1  00 00 00 00  
00C7FC  1               .byte 0
00C7FC  1               .endrepeat
00C7FC  1               
00C7FC  1  00 00        	.byte      0,0     ;0000 blocks = check status
00C7FE  1  03           	.byte      3       ;bit 0=read 1=status
00C7FF  1  35           	.byte     entry&$00FF ;low byte of entry
00C800  1               
00C800  1