Programming Bipolar PROMs (Tom Hunter)

From: Tom Hunter <ccth6600 at gmail.com> Subject: Programming Bipolar PROMs I built a project using Russian clones of the 74188, and ended up building a programmer for them. The programming process is slow (over a minute to program 32 bytes), draws quite a bit of power (the chip is uncomfortably warm afterwards), and it took a while to work out the programming algorithm. Also, as Tom Hunter mentioned, the programming process isn't perfect - about 5% don't program correctly; I don't know if this is my algorithm or the fact that the clones aren't so good. However, once programmed, they seem to work just fine. I bought the Russian devices off eBay for cheap - I think they were about $0.20 apiece, so I got a hundred of them, which I've been slowly nibbling away at as my little product sells. I still have several dozen left; if you'd like you could send me the hex file (or listing - it's only 32 bytes, which I could type in), and I could program a couple for you. I'm not sure I could recommend building your own programmer. It's obviously possible, and there are hand-operated versions floating around on the internet (really hand-operated: set a rotary switch for the bit and five address switches, turn on the power, and push a button for 1-1/2 seconds; repeat for every "1" bit in the PROM), but you'd need more than just the Arduino. You need eight high-side drivers that will handle an amp apiece, plus another driver to switch the power supply voltage between 5 and 13.5 volts, as well as writing a program to implement the algorithm. (actually, it's slow enough that you could get by using relays for all the higher voltage switching.) I don't believe that any modern programmer handles these - if the Data I/O does, then that's probably your only option. ~~ Mark Moulding