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adapted to Kick Assembler, some documentation update

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FeralChild64 committed 2019-09-07 12:35:21 +02:00
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commit de27124b4f
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c64/kernal/readst.s
+17 -17
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@@ -1,30 +1,30 @@
;;
;; Official Kernal routine, described in:
;;
;; - [RG64] C64 Programmer's Reference Guide - page 292
;; - [CM64] Compute's Mapping the Commodore 64 - page 239
;;
;; CPU registers that has to be preserved (see [RG64]): .X, .Y
;;
//
// Official Kernal routine, described in:
//
// - [RG64] C64 Programmer's Reference Guide - page 292
// - [CM64] Compute's Mapping the Commodore 64 - page 239
//
// CPU registers that has to be preserved (see [RG64]): .X, .Y
//
readst:
READST:
;; Check the current device number
// Check the current device number
lda current_device_number
cmp #$02
bne +
bne !+
;; This is RS-232 device - according to 'Compute's Mapping the Commodore 64' page 239
;; it reads status from RSSTAT
// This is RS-232 device - according to 'Compute's Mapping the Commodore 64' page 239
// it reads status from RSSTAT
lda RSSTAT
rts
*
;; According to 'Compute's Mapping the Commodore 64' page 239, it usually retrieves
;; status from IOSTATUS
!:
// According to 'Compute's Mapping the Commodore 64' page 239, it usually retrieves
// status from IOSTATUS
;; XXX is it always the case if device is not RS-232 ?
// XXX is it always the case if device is not RS-232 ?
lda IOSTATUS
rts