mirror of
https://github.com/buserror/mii_emu.git
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101 lines
2.8 KiB
NASM
101 lines
2.8 KiB
NASM
; Smartport Firmware for MII
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; This is included in the MII ROM by mii_smartport.c
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;
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; This is shamelessly lifted and heavily adapted from
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; https:github.com/ct6502/apple2ts/blob/main/src/emulator/harddrivedata.ts
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; With inspiration from Terence Boldt's driver for the ROM card
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;
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; ProDOS defines
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command = $42 ; ProDOS command
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unit = $43 ; 7=drive 6-4=slot 3-0=not used
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buflo = $44 ; low address of buffer
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bufhi = $45 ; hi address of buffer
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blklo = $46 ; low block
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blkhi = $47 ; hi block
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ioerr = $27 ; I/O error code
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nodev = $28 ; no device connected
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wperr = $2B ; write protect error
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knownRts = $FF58
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.org $c000
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.verbose
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entryOffset = $c0 ; entry point offset
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ldx #$20 ; Apple IIe looks for magic bytes $20, $00, $03.
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lda #$00 ; These indicate a disk drive or SmartPort device.
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ldx #$03
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lda #$00 ; $3C=disk drive, $00=SmartPort
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start:
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bit $CFFF ; Trigger all peripheral cards to turn off expansion ROMs
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ldy #$0
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sty buflo
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sty blklo
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sty blkhi
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iny ;set command = 1 for read block
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sty command
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lda #$4C ; jmp
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sta $07FD
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lda #entryOffset ; jump address
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sta $07FE
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jsr knownRts
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tsx
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lda $100,X ; High byte of slot adddress
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sta $07FF ; Store this for the high byte of our jmp command
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asl ; Shift $Cs up to $s0 (e.g. $C7 -> $70)
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asl ; We need this for the ProDOS unit number (below).
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asl ; Format = bits DSSS0000
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asl ; D = drive number (0), SSS = slot number (1-7)
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sta unit ; Store ProDOS unit number here
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lda #$08 ; Store block (512 bytes) at address $0800
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sta bufhi ; Address high byte
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stz buflo ; Address low byte
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stz blklo ; Block 0 low byte
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stz blkhi ; Block 0 high byte
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jsr $07FD ; Read the block (will jmp to our driver and trigger it)
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bcs error
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lda #$0A ; Store block (512 bytes) at address $0A00
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sta bufhi ; Address high byte
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lda #$01
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sta blklo ; Block 1 low byte
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jsr $07FD ; Read
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bcs error
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lda $0801 ; Should be nonzero
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beq error
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lda #$01 ; Should always be 1
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cmp $0800
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bne error
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ldx unit ; ProDOS block 0 code wants ProDOS unit number in X
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jmp $801 ; Continue reading the disk
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error jmp $E000 ; Out to BASIC on error
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.org $c0c0
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; jump back to mii code
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entryHD nop ; Hard drive driver address
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bra magicHD
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bra magicSM
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.org $c0d0
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magicHD .db $db, $fb, $0
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bra done
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.org $c0e0
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magicSM .db $db, $fb, $0
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bra done
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.org $c0f0
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DONE bcs ERR
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lda #$00
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rts
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ERR lda #$27
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rts
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; $CnFE status byte
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; bit 7 - Medium is removable.
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; bit 6 - Device is interruptable.
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; bit 5-4 - Number of volumes on the device (0-3).
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; bit 3 - The device supports formatting.
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; bit 2 - The device can be written to.
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; bit 1 - The device can be read from (must be on).
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; bit 0 - The device's status can be read (must be on).
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.org $c0fe
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.db $17
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.db entryOffset ; entry point offset
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