AppleIISd/AppleIISd.s

********************************
*
* Apple][Sd Firmware
* Version 0.5
*
* (c) Florian Reitz, 2017
*
* X register usually contains SLOT16
* Y register is used for counting or SLOT
*
********************************

               DAT

               XC               ; enable 65C02 code
DEBUG          =     0
               DO    DEBUG
               ORG   $8000
               ELSE
               ORG   $C800      ; Expansion ROM
               FIN

* Memory defines

SLOT16         =     $2B        ; $s0 -> slot * 16
WORK           =     $3C
SLOT           =     $3D        ; $0s
CMDLO          =     $40
CMDHI          =     $41

CURSLOT        =     $07F8      ; $Cs
DATA           =     $C080
CTRL           =     DATA+1
DIV            =     DATA+2
SS             =     DATA+3
R30            =     $0478
R31            =     $04F8
R32            =     $0578
R33            =     $05F8
INITED         =     $0678

* Constants

SSNONE         =     $0F
SS0            =     $0E
DUMMY          =     $FF


********************************
*
* Install SD card driver
*
********************************

* signature bytes

               LDX   #$20
               LDY   #$00
               LDX   #$03 
                              ===== Page 2 =====
 
               STX   WORK

* find slot nr

               DO    DEBUG
               LDA   #$04
               STA   SLOT
               LDA   #$C4
               STA   CURSLOT
               LDA   #$40
               STA   SLOT16
               ELSE
               JSR   $FF58
               TSX
               LDA   $0100,X
               STA   CURSLOT    ; $Cs
               AND   #$0F
               STA   SLOT       ; $0s
               ASL   A
               ASL   A
               ASL   A
               ASL   A
               STA   SLOT16     ; $s0
               FIN
               TAX              ; X holds now SLOT16

               BIT   $CFFF
               JSR   INIT

               DO    0
*
* TODO: check for init error
*

* see if slot has a driver already

               LDX   $BF31      ; get devcnt
INSLP          LDA   $BF32,X    ; get a devnum
               AND   #$70       ; isolate slot
               CMP   SLOT16     ; slot?
               BEQ   INSOUT     ; yes, skip it
               DEX
               BPL   INSLP      ; keep up the search

* restore the devnum to the list

               LDX   $BF31      ; get devcnt again
               CPX   #$0D       ; device table full?
               BNE   INSLP2

               JSR   $FF3A      ; bell
               JMP   INSOUT     ; do something!

INSLP2         LDA   $BF32-1,X  ; move all entries down
               STA   $BF32,X    ; to make room at front
               DEX              ; for a new entry
               BNE   INSLP2 
                              ===== Page 3 =====
 
               LDA   #$04       ; ProFile type device
               ORA   SLOT16
               STA   $BF32      ; slot, drive 1 at top of list
               INC   $BF31      ; update devcnt

* now insert the device driver vector

               LDA   SLOT
               ASL
               TAX
               LDA   #<DRIVER
               STA   $BF10,X    ; write to driver table
               DO    DEBUG
               LDA   #>DRIVER
               ELSE
               LDA   CURSLOT
               FIN
               STA   $BF11,X

INSOUT         RTS
               FIN

BOOT           LDA   #$01
               STA   $42        ; load command
               LDA   SLOT16
               TAX
               STA   $43        ; slot number
               STZ   $44        ; buffer lo
               LDA   #$08
               STA   $45        ; buffer hi
               STZ   $46        ; block lo
               STZ   $47        ; block hi
               BIT   $CFFF
               JSR   READ       ; call driver
               JMP   $801       ; goto bootloader


********************************
*
* Jump table
*
********************************

DRIVER         CLD
               DO    DEBUG
               LDA   #$04
               STA   SLOT