HP Forums

I can see the basic schematic on the June 1991 HP Journal for the 48SX (and S and G/GX) ports. I'm wondering if anyone has more details like the part numbers and or specs on the transistors and IR LED and transistor?

I'm putting together a small USB-serial adapter and was going to see how close I can duplicate the HP's port hardware

That is the part number HP serial cable F1015-80002
I accidentally got HP-48G+ from eBay and the previous owner is very kind to give me many parts. This serial cable is useful with the HP95/100/200LX, too.
It's 4 pin to RS232C on the other end, you need some adapter to make a connection RS232C to USB port.

I have a cable. I'm looking for the actual schematic. I want to duplicate it instead of using a max232 or such.

Actually I found it

https://www.hpcalc.org/hp48/docs/misc/io2.txt

Soldered up a simple protoboard today