Mystery Chips

[bbcmicro]

What I had for lunch at school today, but incidentally I also have 3 chips that identifying

First has 27 pins, and what looks like the mitsubishi logo, has a paper label with printed 098A on it, and the number/serials 'M5M27C256K - 12 850102' Possibly memory of some sort?

The next is the same but with 097A on the sticker.

The last is 40 pin, Intel and D8742 8529051 (C) Intel '82

[chuckcmagee]

First 2 are WAY easy. EPROMs. Very standard issue. 3rd one is some kind of Intel CPU chip. Do a now famous google on "intel d8742" when you get a chance.

[bbcmicro]

I assume it's impossible to guess what was/is on them?

[chuckcmagee]

Not really that hard if you have access to an "prom programmer". Even my newly purchased PX-8 can read those. If fact, those are EXACTLY what I could use in my PX-8 to store programs on. Anyway, just need a computer that can read that style prom and dump it out like regular ram.

It's funny. I JUST learned bunches about 27C256 just because of my PX-8. I was thinking of buying a prom programmer on ebay but it's too much hassle changing the proms on the PX-8. It has a cardboard cover with metal on it over the proms and the cardboard tends to get more and more messed up as you change proms.

[carlsson]

But 27 pins? Sounds like one pin was broken off. Normally those are 2x14 = 28 pins.

[Thrashbarg]

An 8742 (8042) is a microcontroller, a bit like the 8051. It was most commonly used in IBM AT keyboard controllers on the motherboard and in the keyboard itself for PC/XT/AT's and clones.

I have a few lying around and can't find much information on them as keyboard controllers. I wanted to use one as an AT keyboard interface for my 8080 computer.

[bbcmicro]

Thanks,

Yes, it is 28. I'm just bad at maths

[carlsson]

Good to hear. I mean, sometimes it is easier to relearn the difference between odd and even numbers than to solder in a replacement pin for one that has broken.

[ziloo]

I actually did that once, I mean soldering a replacement pin for a broken one.
The pin was broken from the very end, and only a very short metalic stem
was visible sticking out of the chip. The job was more like a surgery :biggrin:.

[carlsson]

Err.. I have done that twice recently, when I lifted old EPROMs and one pin unfortunately got stuck and broke. I'm far from a skilled craftsman with the soldering iron, but it was functional afterwards.