Apple-2-HW/Apple2-IO-RPi
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Revert "Avoid unwanted i/o access."

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Neither the original hardware type nor the alternative hardware type have any read and write i/o port share addresses. Therefore phantom reads aren't an issue with those hardware types.

This reverts commit ae5cb754fb.
This commit is contained in:
Oliver Schmidt 2022-08-19 10:13:05 +02:00 committed by Terence Boldt
parent 4c2e938474
commit 0aa485762a
2 changed files with 12 additions and 23 deletions
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18
Apple2/RPi.Command.asm
View File

@ -17,15 +17,10 @@ XLEN = $BE52 ;length of command string-1.
XCNUM = $BE53 ;CI cmd no. (ext cmd - 0). XCNUM = $BE53 ;CI cmd no. (ext cmd - 0).
PBITS = $BE54 ;Command parameter bits. PBITS = $BE54 ;Command parameter bits.
XRETURN = $FF58 ;Known RTS instruction. XRETURN = $FF58 ;Known RTS instruction.
InputByte = $c08e
; have 6502 absolute indexed access phantom reads OutputByte = $c08d
; happen on page $bf to avoid unwanted i/o access InputFlags = $c08b
IndexOffset = $8f OutputFlags = $c087
InputByte = $c08e - IndexOffset
OutputByte = $c08d - IndexOffset
InputFlags = $c08b - IndexOffset
OutputFlags = $c087 - IndexOffset
ReadBlockCommand = $01 ReadBlockCommand = $01
WriteBlockCommand = $02 WriteBlockCommand = $02
@ -81,10 +76,9 @@ DetectSlot:
asl asl
asl asl
asl asl
clc
adc #IndexOffset
tax tax
bcc Start ;always clc
bcc Start
nextSlot: nextSlot:
dex dex
bne DetectSlot bne DetectSlot

17
Apple2/Shell.asm
View File

@ -19,14 +19,10 @@ IOError = $27
NoDevice = $28 NoDevice = $28
WriteProtect = $2B WriteProtect = $2B
; have 6502 absolute indexed access phantom reads InputByte = $c08e
; happen on page $bf to avoid unwanted i/o access OutputByte = $c08d
IndexOffset = $8f InputFlags = $c08b
OutputFlags = $c087
InputByte = $c08e - IndexOffset
OutputByte = $c08d - IndexOffset
InputFlags = $c08b - IndexOffset
OutputFlags = $c087 - IndexOffset
ResetCommand = $00 ResetCommand = $00
ReadBlockCommand = $01 ReadBlockCommand = $01
@ -89,10 +85,9 @@ DetectSlot:
asl asl
asl asl
asl asl
clc
adc #IndexOffset
tax tax
bcc Init ;always clc
bcc Init
nextSlot: nextSlot:
dex dex
bne DetectSlot bne DetectSlot