82S126/82S129/82S131 bi-polar PROM replacement kit (82S129-82S131-to-27512)

What is it

The 82S129-82S131-to-27512 is a universal replacement solution to replace 82S129 or 82S131 bi-polar PROMS with newer easy to find fast EEPROMs. This kit is a very small adapter board that can take a cheap and easy to find W27C512 EEPROM and replace 82S129 or 82S131 bi-polar PROMS.


I created this kit as I work on a lot of early 80s arcade games, every once in a while I need to replace a 82S129 or 82S131 bi-polar PROM. These bi-polar PROMS were made in the 70s and VERY hard to find, and VERY expensive and the most of normal in-expensive programmers will not even program them. Whenever I needed one I needed to use a outside source and it was expensive to get.

I designed this adapter to solve the problem and allow me to replace 82S129 or 82S131s with FAST electrically erasable EEPROMS. I personally use a W27C512 45 ns EEPROM.

What's included and what does it look like

The 82S129-82S131-to-27512 is the UN-ASSEMBLED parts to make the adapter board as shown in the image

You will receive the parts to make 4 adapter boards, which include:

  • 4 x adapter PCB boards
  • 4 x 28 pin solder tab sockets
  • 8 x 8 pin terminal strips

How does it work

It's very easy, follow these steps in ORDER:
  1. Solder together the header pins into the board.
  2. Solder the socket into the new board
  3. Program the replacement EEPROM in an EEPROM programmer (such as the GQ-4X), and program the ROM image to want to replace. There is NO need to "double, triple, or quadruple" the image on the new chip, simply burn the image AS is.
  4. Set the appropriate solder jumpers to specify the PROM type you are replacing, using the figure below.
  5. Insert the programmed EEPROM into the socket
  6. Insert adapter into game board ROM socket!
  7. Play!

Jumper Settings


  • Most uses of these 82S* series PROMs must have VERY fast access times you CANNOT use normal EPROMS with access times in the hundreds of nanoseconds to replace these. The EPROMS included with the EEPROM options the (Winbond 27C512-45) are VERY fast and have worked in my limited tests (galaga, millipede, and crystal castles, food fight to date). However I CANNOT guarantee they will work for your specific use.


Approx dimensions when assembled:
1 1/2" wide
15/16" wide
3/4" tall (including height of a WC27512 inserted into the socket, including length of adapter legs)


These can also be used to read data off of existing 82S129/82S131s. (you cannot read off of a 82S126 without external electronics) Simply set the correct solder jumpers. Then instead of installing 2 x 8 pin terminal strips, instead install a 16 pin socket. Instead of installing a 28 pin socket, install 2 x 12 pin headers. Then insert the original 82S129/82S131 in the socket. Read the chip in a EPROM programmer as a 27512.

NOTE there is an error in the newer model of this adapter and reading 82S129's is broken, it can be easily fixed. If you wish to use this adapter for reading 82S129s rather than replacing them, flip the adapter over and solder together pins #13 and #14 of the 16 pin socket as shown below

Important note:
When reading as a 27512 you will have 65536 bytes data file.
Use the appropriate online converter to convert the file

Each top most significant 4 bits will be 0xFF for each byte, you may or may not to remove each top 4 bits for eac address depending on the file that ou are comparing against. (with MAME ROM dumps there is no need to remove the top 4 bits of each byte)

How do I buy them?

Buy them on

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