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Transactor_27_1988_Transactor_Publishing.d64
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devpres.src
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Commodore BASIC
|
2023-02-26
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737b
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36 lines
100 sys 700
110 ;paul g. sawyer
120 ;
130 ;orangeville, on
140 ;
150 ;
160 ;device presence checker
170 ;-----(relocatable)-----
180 ;put device # in location 252
190 ;after calling routine, read
200 ;location 251. if its value is
210 ;0 then the device is off, or
220 ;1 then the device is on.
230 ;
240 ;note- if using device 8 or 9
250 ;and drive is on, the error light
260 ;will be flashing, but just
270 ;initialize the drive and all
280 ;will be ok.
290 ;
300 *=$c000
310 .opt oo
320 device = $fc
330 onflag = $fb
340 lda #0: sta onflag
350 lda device: tax: ldy #0
360 jsr $ffba ;setlfs
370 lda #1: ldx onflag: ldy #0
380 jsr $ffbd ;setnam
390 jsr $ffc0 ;open
400 lda $90: pha
410 lda device: jsr $ffc3 ;close
420 pla: bmi off
430 on lda #1: sta onflag
440 off rts