You are watching a 4Mbit RAM expansion module for the Stag PP39 EPROM programmer. The standard RAM in this programmer is 512Kbit - the larger EPROM you can program is 27C512
If you need to program larger EPROMs like 27C010, 27C020, 27C040, 27C1024, 27C4096 and many others, you will need a RAM expansion.
You can check how much memory your device has by pressing SET followed by 4 (in local mode) and you'll have the size in Hexadecimal notation:
10000 - 512Kbit
20000 - 1Mbit
40000 - 2Mbit
80000 - 4Mbit
I do have many Stag programmers and finding an expansion is impossible as Stag no longer produces it. Because I had to make extra PCBs, here is your chance to have your own expansion.
Simple instalation, less than 5 minutes and no soldering. Instructions provided.
The price includes tracked shipping to anywhere in the world.
Contact if you need help.