[cctalk] VT100: Datasheet for Intel 8228

Hello, I have a non-functioning VT100. I think I may have isolated the problem to an Intel 8228 chip (or 88228, the schematic says 8228, the part is marked 88228C). Certainly, the part gets a bit hot and it doesn't seem to be outputting anything on the I/O W pin (pin 27) despite activity on STSTB (pin 1), DBIN (pin 4) and WR (Pin 3). There is no activity on the HLDA input though, but I am not sure if that is required because I think the firmware is just trying to send its status to the keyboard LEDs. I can find a brief datasheet for the 8228 but it doesn't tell me the logic for producing the I/O W signal, so I am not sure if it is behaving as it should. Does anyone have more comprehensive information on how the 8228 is supposed to work? I have dumped the ROMs and been able to capture the ROM reads and they match the disassembled code, so I think the 8080 CPU itself is working. Thanks Rob