Interesting, not seen this one before... The "SC100S" strongly suggests this was marketed by Reveal Computer Products. Normally they just relabeled Aztech's regular designs, but this isn't one of the designs I'm familiar with and it also doesn't map with any of the layouts on TH99. Also no hits on …

bump II have a similar motherboard too - SBC386At25F04, manual missing. But that's not the main problem with it. The mainboard powers up, but the keyboard LEDs are flashing continuously and it seems to be running like in slow motion - I had to wait about half minute until the speaker began to beep …