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5493c9e7c2
The Receive Data Register and the Transmit Data Register share share a single address. Accessing that address with STA abs,X in order to fill the Transmit Data Register causes a 6502 false read which causes the Receive Data Register to be emptied. The simplest way to work around that issue - which I chose here - is to move the base address for all ACIA accesses from page $C0 to page $BF. However, that adds an additional cycle to all read accesses. An alternative approach would be to only modify the single line `sta ACIA_DATA,x`. |
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| .. | ||
| apple2 | ||
| atari | ||
| atari2600 | ||
| atari5200 | ||
| atari7800 | ||
| atmos | ||
| c16 | ||
| c64 | ||
| c128 | ||
| cbm | ||
| cbm510 | ||
| cbm610 | ||
| common | ||
| conio | ||
| creativision | ||
| cx16 | ||
| dbg | ||
| em | ||
| gamate | ||
| geos-apple | ||
| geos-cbm | ||
| geos-common | ||
| joystick | ||
| lynx | ||
| mouse | ||
| nes | ||
| none | ||
| osic1p | ||
| pce | ||
| pet | ||
| plus4 | ||
| runtime | ||
| serial | ||
| sim6502 | ||
| supervision | ||
| sym1 | ||
| telestrat | ||
| tgi | ||
| vic20 | ||
| zlib | ||
| Makefile | ||