Looking for: HP 9000/216 (9816) keyboard

Yes, you can. It's worth doig nthe mainboard mod if you have a load of 41256s, as the machine only has 2 expansion slots (one of which allowas for an external connector on the PCB in normal DIO fashion), so you don't want to waste them. I think I have 2M RAM (1M o nthe motherboard and a 1M RAM card) and a 98622 GPIO interface in mine. I am sure you know this, but the 50 pin microribbon conenctor on the mainboard is an RS232 port. You will ahve to get or make a cable to a DB25. The wirelist for this cable is not in any of the obvious docuemtnaion, I think it's hidden in one of the BASIC manuals, and there is an HP cable manual on bitsavers. Which text vdieo board do toy have? I am told there was one tht didin't support attributes (half-brightness, etc on the text display. The one I have does. [Keyboard] I got one minor detail wrong (but it's obvious from the scheamtics). There are really 2 signal lines between the machine and the kayboard. One, from machine to keyboard, is a clock line.The other is bidirectional. From keyboard to machine, it indicates whether the key is pressed (or the appropriate bit of the twiddleknob counter). But if the machine asserts in on the appropriate edge of the clock (it's clear from the schematics, which are not in front of me), the scan counter in the keyboard is cleared. That's the 'reset' If you ahv to make one, you have a choice. You could copy the original design, it's just common 4000-series CMOS parts, nothing custom or programmed. Or I'll bet a microcontroller could easily keep up with the interface singals. so you could use that. -tony