Programming/General Reference/KERNAL History
The KERNAL RS-232C service routine is buggy and was supposedly never tested. The routine has two major defects:
1) The instructions at $EAA7 and $EAA9 have to be swapped to allow null characters to be received:
>EAA7
STA $07D5
BEQ $EAC2
2) A PLA instruction needs to be injected before $EB1E to allow XON/XOFF control characters to be transmitted:
>EB1B
JMP $FCD8
>FCD8
STA $07CF
PLA
JMP $EB1E
KERNAL patch:
forum/45313
The defect is mentioned here:
https://archive.org/details/YourCommodoreIssue35Aug87/page/n77/mode/2up
forum/16281
forum/24936
forum/36477
forum/43757
forum/43869
RS-232C bug |
