This is a tested and working project

Almost all Retro Computer enthusiast has an EPROM programmer device, be it the most common TL866-II or any other one, if it has a 40 pin ZIF socket you need an adapter board for larger pin devices.

This is a very simple, small and easy to use adapter. I needed to program some 27C800 EPROMs for my Amiga 500+ and I noticed that my trusty TL866-II programmer cannot do them natively. However, it could do a 27C4096 (40 pin 512KB EPROM) which had a totally different pin out, but its programming specs were identical with a 27C800 (or 27C400). So, all I needed was to "translate" the pins and trick the programmer into thinking it is programming a 27C4096 while actually it was programming a 27C800. After testing this theory successfully on a breadboard with lots of jumper cables, I designed this small PCB. A lot of routing was necessary, so I made it a 4-layer board to keep all the traces as short and as isolated from each other as possible.

Required parts, how to assemble and use this adapter is explained in detail in the attached PDF document.

This adapter is made and tested for TL866-II programmer, but it will work with any other programmer which is capable of programming a 27C4096 EPROM. It will NOT work for programming any other device other than 27C800 and 27C400.