UP9600: XMODEM sends stray $FF at beginning
mist64 opened this issue · 2 comments
mist64 commented
When running the XMODEM test with the UP9600 driver, CCGMS sends an $FF byte before sending NAK/'C'.
This does not happen with the User Port or SwiftLink driver.
This reproduces with CCGMS 2021; it is not a CCGMS Future regression.
mist64 commented
Also, it sends a stray $00 at the end part of the transmission protocol:
- in: last byte (CRC)
- out: ACK ($06)
- in: EOT ($04)
- out: $00 – instead of ACK ($06)
mist64 commented
Both issues are probably caused by the call to enablexfer
, which happens at exactly these spots. These ultimately call into up9600_enable
, which does a lot of CIA#1 setup, which may cause an extra byte to be sent.