diff options
Diffstat (limited to 'setmem.s')
| -rw-r--r-- | setmem.s | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/setmem.s b/setmem.s new file mode 100644 index 0000000..0b53c61 --- /dev/null +++ b/setmem.s @@ -0,0 +1,267 @@ +; 20221210 bkw: reverse-engineered "source" for setmem.xex. +; originally created with da65 (cc65's disassembler), then +; hand-edited to make it (hopefully) more human-readable. + +; By default, this builds the original setmem.xex, 877 bytes, +; md5sum f7834eaf50e8b5d5314a20f6a5d83a0d. + +; I've added a couple of optional defines: +; reverse_logic - For upgrades that have 256K/compy as the default. +; coldstart - Reboot the Atari instead of exiting to DOS. For use +; with SpartaDOS X, which crashes if we exit to DOS +; after changing the mode. +; See the Makefile for build options. + + .include "atari.inc" + .include "xex.inc" + .include "inv.inc" + +; 2 byte ZP pointer used for printing text. +msgptr = $cc + +; "Magic" hardware register. On an un-upgraded Atari, $d3f3 is just +; a "mirror" of $d303 (aka PBCTL). It's special on the tfhh upgrade +; though: changing it to $d303 here results in a non-functional setmem.xex. +; Also note that writing to $d3f3 only affects the upgrade if the +; Start key is pressed... and even when Start is pressed, writing +; to $d3f3 still changes PBCTL. +magic_register = $d3f3 + +loadaddress = $3000 + + xex_org loadaddress + +entrypoint: + cld ; unnecessary. + lda #$08 + sta CONSOL ; clicks the consol speaker (no idea why). + lda #$00 + sta choice ; choice = 0 (but it immediately gets inc'd to 1). +next_choice: + inc choice ; choice++; + lda choice + cmp #$03 + bne choice_ok + lda #$00 ; if(choice == 3) choice = 0; + sta choice +choice_ok: + lda #<banner_msg + sta msgptr + lda #>banner_msg + sta msgptr+1 + jsr print_msg + lda choice + clc + asl a + asl a + tay ; Y = choice * 4; + lda msg0,y + sta msgptr + lda msg0+1,y + sta msgptr+1 + lda magicbits_0,y + sta magic_bits + jsr print_msg +read_consol: + lda CONSOL + and #$07 + cmp #$03 + beq option_pressed + cmp #$06 + beq start_pressed + cmp #$05 + bne read_consol +select_pressed: + lda CONSOL + and #$07 + cmp #$07 + bne select_pressed + beq next_choice +option_pressed: + lda #<no_change_msg + sta msgptr + lda #>no_change_msg + sta msgptr+1 +print_and_exit: + jsr print_msg + lda #$00 + tax + tay + rts + +; apply the current choice to the hardware +start_pressed: + sei ; disable IRQs + lda #$00 + sta NMIEN ; disable NMIs + lda magic_register + and #$FC + ora magic_bits + sta magic_register +wait_consol_release: + lda CONSOL + and #$07 + cmp #$07 + bne wait_consol_release + lda #$40 + sta NMIEN ; re-enable NMIs + cli ; re-enable IRQs + .ifdef coldstart + jmp COLDSV + .else + lda #<mode_set_msg ; "Mode was set...." + sta msgptr + lda #>mode_set_msg + sta msgptr+1 + jmp print_and_exit + .endif + +; print null-terminated ATASCII message pointed to by (msgptr). +print_msg: + lda #$00 + tax + tay + sta ICBLL,x + sta ICBLH,x + lda #PUTCHR + sta ICCOM,x + lda msgptr + sta ICBAL,x + lda msgptr+1 + sta ICBAH,x +nextchar: + lda (msgptr),y + beq call_cio + iny + bne zptr_hi_ok + inc msgptr+1 +zptr_hi_ok: + inc ICBLL,x + bne nextchar + inc ICBLH,x + bne nextchar +call_cio: + jmp CIOV + + +; R/W data (2 bytes): + +choice: .byte $00 ; Currently chosen option (default 1, range 0 to 2). + +; This gets set to one of disable_magic, compy_magic, or rambo_magic. +; Bits 0 and 1 will get ORed into magic_register. +magic_bits: .byte $00 + + +; R/O data (rest of file): + + disable_magic = $01 + + .ifdef reverse_logic + compy_magic = $00 + rambo_magic = $02 + .else + compy_magic = $02 + rambo_magic = $00 + .endif + +; Table of 3 4-byte entries, one per choice. 4th byte is filler (always 0). +msg0: .addr disable_msg +magicbits_0: .byte disable_magic +filler_0: .byte 0 + +msg1: .addr compy_msg +magicbits_1: .byte compy_magic +filler_1: .byte 0 + +msg2: .addr rambo_msg +magicbits_2: .byte rambo_magic +filler_2: .byte 0 + +; Rest of the data is messages to be printed to IOCB#0 by print_msg. +; These are null-terminated. +banner_msg: + .byte CLS + .byte EOL + inverse " Setup tool for tfhh SRAM expansions " + .byte EOL,EOL + + .ifdef reverse_logic + inverse "Reverse Logic" + .byte " - This" + .else + .byte "20210614" + .byte " - This tool" + .endif + .byte " works with:" + + .byte EOL,EOL + .byte "- 512 KB SRAM memory expansion " + inverse "V4.5" + .byte EOL + .byte " (please check revision number!)" + .byte EOL,EOL + .byte "- 576 KB SRAM memory expansion " + inverse "V2" + .byte EOL + .byte " (only for the Atari 600XL, please" + .byte EOL + .byte " check the presence of " + .byte '"', "V2", '"', " printed", EOL + .byte " on the PCB)" + .byte EOL,EOL + + .byte "Use console key " + inverse " SELECT " + .byte " to change" + .byte EOL + .byte "the desired mode, press " + inverse " OPTION " + .byte " to" + .byte EOL + .byte "quit this tool without any change" + .byte EOL + .byte "or press " + inverse " START " + .byte " to setup the SRAM" + .byte EOL + .byte "memory expansion as shown and" + .byte EOL + .ifdef coldstart + inverse "reboot" + .byte " the Atari." + .else + .byte "return to DOS." + .endif + + .byte EOL,EOL + .byte "Expansion will be set to: " + .byte EOL,EOL + .byte "==> " + .byte 0 + +disable_msg: + inverse " Memory Expansion switched off" + .byte 0 + +compy_msg: + inverse " 256 KByte Compy-Shop/XE mode" + .byte 0 + +rambo_msg: + inverse " 512 KByte RAMBO mode" + .byte 0 + +mode_set_msg: + inverse " " + .byte EOL,EOL + .byte "Mode was set. Program terminated." + .byte EOL,EOL,0 + +no_change_msg: + inverse " " + .byte EOL,EOL + .byte "Nothing changed. Programm terminated." + .byte EOL,EOL,0 + + xex_run entrypoint |