Reply 1 of 3, by vstrakh
Some forums references them as "the same chip". I'd guess the A vs B indicates the silicon revision or the speed grade, but to tell for sure you'd need datasheets, I couldn't google it 🙁
Reply 2 of 3, by EnergyStar
Thank you dear friend. I replaced the chip, nothing bad happened.
Reply 3 of 3, by mkarcher
EnergyStar wrote on 2022-06-28, 21:45:
Can these chips be used interchangeably? […]
Can these chips be used interchangeably?
The UM8663AF comes from the Shuttle HOT-433 motherboard
The UM8663BF comes from the GA-5486al rev.2c motherboard
I would like to test the UM8663BF on the Shuttle HOT-433.
If I remember correctly what I saw when I reverse engineered BIOSes, the A and B chip have different configuration capabilities, with the later B version being more flexible, allowing something like providing COM1 and COM3 onboard with COM2 being provided by an ISA card, whereas the A variant only supports one even-numbered (1/3) and one odd-numbered (2/4) COM port.
On some boards, the BIOS auto-detects whether the A or B variant is installed and adjust the choices availablr in the BIOS setup. Worst case: Some options you can set in the CMOS behave in strange ways if you swap A/B chips and the BIOS is not prepared.