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Clearer wording for the firmware check

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This commit is contained in:
Colin Leroy-Mira
2023-09-10 22:34:03 +02:00
committed by Oliver Schmidt
parent 38f7daf40e
commit aa5ee8423a
1 changed files with 14 additions and 6 deletions
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20
libsrc/apple2/ser/a2.ssc.s
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@@ -133,18 +133,26 @@ ParityTable:
.byte $A0 ; SER_PAR_MARK .byte $A0 ; SER_PAR_MARK
.byte $E0 ; SER_PAR_SPACE .byte $E0 ; SER_PAR_SPACE
; (*): The first byte we'll check at offset 0 is ; Check five bytes at known positions on the
; expected to be a BIT instruction on any Apple2 ; slot's firmware to make sure this is an SSC
; machine with an ACIA 6551, including the //c ; (or Apple //c comm port) firmware that drives
; and //c+. ; an ACIA 6551 chip.
;
; The SSC firmware and the Apple //c(+) comm
; port firmware all begin with a BIT instruction.
; The IIgs, on the other hand, has a ; The IIgs, on the other hand, has a
; Zilog Z8530 chip and its firmware starts with ; Zilog Z8530 chip and its firmware starts with
; a SEP instruction. We don't want to load this ; a SEP instruction. We don't want to load this
; driver on the IIgs' serial port. ; driver on the IIgs' serial port. We'll
; differentiate the firmware on this byte.
; ;
; The next four bytes we check are the Pascal ; The next four bytes we check are the Pascal
; Firmware Protocol Bytes that identify a ; Firmware Protocol Bytes that identify a
; serial card. ; serial card. Those are the same bytes for
; SSC firmwares, Apple //c firmwares and IIgs
; Zilog Z8530 firmwares - which is the reason
; we have to check for the firmware's first
; instruction too.
IdOfsTable: IdOfsTable:
.byte $00 ; First instruction .byte $00 ; First instruction