The two connectors at the top remind me of the MITS 2SIO board. Chip on the left with the label seems odd ? looks like an EPROM. Not sure why they?d use a UART (40-pin chip) and an ACIA, but it?s an interesting two-port combo board. Get Outlook for iOS On Tue, Jul 10, 2018 at 10:17 PM -0400, "dwight via cctalk" < cctalk at classiccmp.org> wrote: I'm thinking one serial and one cassette. The 8251 for the cassette. I can't make out all the chips at the pins? The board was hand laid out. Is there nothing on the bottom but traces? Dwight ________________________________ From: cctalk on behalf of Ethan via cctalk Sent: Tuesday, July 10, 2018 6:43:12 PM To: cctalk at classiccmp.org Subject: Can anyone identify this S100 serial board? Trying to identify the S100 serial board in my Imsai 8080. https://imgur.com/eZyOVT5 I assume it was a kit. There are wires from behind one of the ICs that go to DB25 on the rear, along with other DB25s with a few pins (maybe cassette input.) Any help appreciated. -- : Ethan O'Toole