superkato1k wrote on 2023-11-02, 22:05:

Does anyone know if the CT2800's I/O channel enable/disable jumper (JP1) affects the IDE CD-ROM connector as well, or only the audio I/O?

That jumper does not enable/disable any kind of I/O channel - that jumper disconnects or connects the "IOCHRDY" (I/O channel ready) signal from the IDE cable to the ISA bus. Contrary to most other bus systems, the ISA bus is "ready by default", and cards that can not repsond in "standard time" have to signal "not ready" explicitly by pulling "IOCHRDY" low. Pulling IOCHRDY low can block the ISA bus theoretically indefinitely, but pulling it low longer than 15us will interfere with RAM refresh on PC/XT/AT systems and is forbidden. Some pre-standard, borderline compatible or broken drives seem to use the IOCHRDY pin for a different purpose, so many IDE controllers offer the possibility to prevent an apparent "not ready" signal from the IDE device to reach the ISA bus. Nearly all devices can respond fast enough that conventional ISA timings can be achieved in all circumstances, so IOCHRDY is unnecessary. Some drives need IOCHRDY support to operate at faster modes like PIO3 that are way faster than "standard ISA timings", as they can achieve the PIO3 speed only most of the time, but sometimes need to "take a break".

mkarcher wrote on 2023-11-02, 23:05:

superkato1k wrote on 2023-11-02, 22:05:

Does anyone know if the CT2800's I/O channel enable/disable jumper (JP1) affects the IDE CD-ROM connector as well, or only the audio I/O?

That jumper does not enable/disable any kind of I/O channel...

I had no idea, thank you so much for clearing this up. I was a little bit confused by it existing at all, but that does make sense!