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This.Apple DA: Detect mockingboard. Resolves #84

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This commit is contained in:
Joshua Bell 2018-06-27 20:59:40 -07:00
parent e6877b3785
commit a12a8d3739
1 changed files with 34 additions and 0 deletions
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desk.acc/this.apple.s
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@ -374,6 +374,7 @@ str_modem: PASCAL_STRING "Modem"
str_audio: PASCAL_STRING "Audio Card"
str_storage: PASCAL_STRING "Mass Storage"
str_network: PASCAL_STRING "Network Card"
str_mockingboard: PASCAL_STRING "Mockingboard"
str_unknown: PASCAL_STRING "(unknown)"
str_empty: PASCAL_STRING "(empty)"
@ -1038,10 +1039,43 @@ notpas:
cmp #9
bne :+
result str_network
:
jsr detect_mockingboard
bcc :+
result str_mockingboard
:
result str_unknown
.endproc
;;; Detect Mockingboard
;;; Assumes $06 points at $Cn00, returns carry set if found
.proc detect_mockingboard
ptr := $06
tmp := $08
ldy #4 ; $Cn04
ldx #2 ; try 2 times
loop: lda (ptr),Y ; 6522 Low-Order Counter
sta tmp ; read 8 cycles apart
lda (ptr),Y
sec ; compare counter offset
sbc tmp
cmp #($100 - 8)
bne fail
dex
bne loop
found: sec
rts
fail: clc
rts
.endproc
;;; ============================================================
;;; Update str_memory with memory count in kilobytes