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; initial load segment for taipan. intended to be a tiny (1-sector)
; routine that checks for the presence of BASIC or a cartridge, and aborts
; the load if found. Also, it resets RAMTOP to RAMSIZ and does a GRAPHICS
; 0, to avoid problems with funky loaders leaving the graphics screen
; in the wrong place (Atarimax flash cart leaves it at $9cxx) or in the
; wrong graphics mode (Fenders 3-sector loader doesn't set up GR.0).
; cl65 -o checkmem.xex -t none checkmem.s
.include "atari.inc"
start = $0600 ; use page 6 for now
.word $ffff
.word start
.word end-1
.org start
; message is "Need 48K, remove cartridge" in screen codes.
msg:
.byte $2e, $65, $65, $64, $00, $14, $18, $2b
.byte $0c, $00, $72, $65, $6d, $6f, $76, $65
.byte $00, $63, $61, $72, $74, $72, $69, $64
.byte $67, $65
msglen = * - msg - 1
S: .byte "S:",0
init:
lda RAMSIZ
cmp #$c0
php
sta RAMTOP
ldx #6*$10 ; CLOSE #6
lda #CLOSE
sta ICCOM,x
jsr CIOV
; GRAPHICS 0
ldx #6*$10 ; IOCB #6
lda #OPEN
sta ICCOM,x
lda #$1c ; $c = read/write
sta ICAX1,x
lda #0 ; aux2 byte zero
sta ICAX2,x
lda #<S
sta ICBAL,x
lda #>S
sta ICBAH,x
jsr CIOV
plp
bcc have_cart
; if RAM size is $c000 or higher, we're OK, just exit.
rts
have_cart:
; if RAM size is below $c000, we have a cartridge (or XL BASIC).
; print the "remove cart" message...
lda #<msg
sta FR0
lda #>msg
sta FR0+1
ldy #msglen
msgloop:
lda (FR0),y
sta (SAVMSC),y
dey
bpl msgloop
sty CH ; y == $ff at this point, clear keyboard
; ...wait for a keystroke...
wait4key:
cpy CH
beq wait4key
; ...and do a warmstart.
jmp WARMSV
end:
.word INITAD
.word INITAD+1
.word init
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