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I’m working on building a ROM adapter for an old Tandy laptop, and it has a DIP socket like none I’ve ever seen. It will hold a standard .600" 28-pin EEPROM, but it’s fully enclosed, and contacts the pins by pushing on the outside, rather than by gripping the pins themselves. I want to get one of these sockets for programming the ROMs, but I can’t find what this type of socket is called. Anything I search for as a “DIP socket” returns only the standard type socket that we all know. Any ideas what this thing is called?
Thanks for looking! Here’s the rub: It doesn’t hold a standard DIP. The pinout on the motherboard is not comparible with any modern or old chip. It holds a chip on a carrier PCB that has pins remapped. (Why!?!?!?) Sorry for the crummy photo quality, it’s the only one I had in my photo archive. As you can (hopefully) see, the PCB edge is where the contact is. No pins at all!
That is very likely a full custom chip carrier system designed for Tandy that was cheaper than the standard ZIF sockets of the day. Your best bet is probably to find another laptop that is dead and salvage the carrier system.
I was really afraid that was going to be the answer. Fortunately, I do have a “test system” that I use for a bunch of things, but the option ROM socket is not (ever, ever) going to be used, so I’ll just carefully unsolder it, and put in a standard DIP socket in case worse comes to worse. Thanks!
The only other time I saw a carrier / pin remapping PCB was on a piece of equipment where they wanted to avoid a double-sided board. They had a finished design except that in the area of the boot ROM they needed to have a double sided board for 6 vias to remap three pins. So they decided to explore the possibility of a custom pinout of a standard ROM.
The final production devices were ROMs that had three pins swapped around but otherwise were standard devices. The engineer commented that if you were going to buy 50,000 devices then Texas Instruments would make you a custom chip (with whatever part number you wanted, as long as it was YOUR part number). So the original designers designed and built a remapping PCB so that they could do the R&D with standard PROM parts and then produce with the custom pinout ROMs. (This was in the APPLE II era)
