The HP 82915 Modem (for the Integral) that I mentioned in another message, uses a 3-chip chipset from Rockwell. The chips are R5313-14, R5132-14 and 10464-14. THe first 2 are 64 pin QIL zig-zag pin packages, the last is a 40 pin DIL. Now, I have the 1985 Rockwell databook here, which covers modems. It appears you could buy a ready-assembled PCB from Rockwell containing these chips and the support components. I have data on that. You could also buy the chips not-on-a-PCB, as the R1212DS 'device set'. Alas I have no real data on those, the book refers me to 'R1212 Modem Device Set Manual', order number 652. And I don't have that. Does anyone have it? Failing that, does anyone have 'R2424 Modem Device Set Manual), order number 651 (this is the 2400 bps version). The chips seem to be somewhat related. What I am relally looking for is complete pinouts of all 3 chips. This may not be in those manuals, though. I have the service manaul for the Amstrad PPC, which includes a schematic of its internal modem. That used the R2424 chipsset, but the schematic does not name most of the pins on these chips, only those that go to other parts of the modem. The internconnections between the 3 chips in the chipset are shown, but not named. I am wondering if the Manual just told you to link pin 7 on the Tx chi to pin 15 on the Rx chip (or whatever, that is a ficticious connection!), and didn't tell you what that signal was. -tony