TMS2532 / TMS2732 Compatible ROM Chip

TMS2532

The TMS2532 was a 32768-bit electrically programmable read-only memory (EPROM), manufactured by the Texas Instruments Corporation. It had a 4 K × 8 organisation and was ultraviolet-light-erasable through a small window. It was utilised on a wide range of home computers in the 80s and 90s, and usually found in the Sinclair ZX80.

In the late 90s, most of these integrated circuits (IC) were recycled for their gold content; however, there are still mountains of old panels waiting to be recycled with them in. There are also many compatible IC chips, such as the TMS2732, that will work after a small modification.


Programmer

TMS2532JL-30

Programming the TMS2532 IC requires +25 V to pin 21 (Vpp). After programming, this pin is no longer used and is usually disconnected. I have not cut this pin on my replica and it appears to be working fine without any problems.

If you have an EPROM programmer then it is very easy to program these chips. You will also need to obtain the ROM binary file.

Direct Equivalents

Here is a list of memory chips that are a direct replacement to the 2532 as used on the original Sinclair ZX80.

  • TI TMS2532
  • Hitachi HN62532
  • Motorola MCM2532
  • Motorola MCM25L32
  • National MM2532

TMS2732A Equivalents

Here is a list of 2732 EPROM chips compiled using my old 1980s data books.

  • TI TMS2732A
  • AMD AM2732
  • Fairchild F2732
  • Fujitsu MBM2732A
  • Hitachi HN462732
  • Intel 2732A
  • Mitsubishi M5L2732
  • NEC LPD2732
  • OKI MSM2732
  • Toshiba TMM2732

The 2732 series also has a 4 K × 8 organisation and is compatible with the 2532 IC; however, it requires a slight modification. If you compare the datasheets of the two chips, using the links below the page, you will notice that pin 18 and pin 21 appear reversed.

On the 2732, pin 21 is A11; this should be in the place of pin 18 where the chip enable pin is. It is possible to connect this pin to the correct place by bending it so that it does not fit into the chip socket, and then soldering a small length of wire to connect it to the correct place.


Cost

The TMS2732 and the TMS2532 are available on eBay and the prices can vary from as little as £2.00.

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TMS2532
TMS2732