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easy eprom questions

Hi Group,

I am a foolish hobbyist who would like to program 27XX eproms sometime within the next year.

First question: I pulled what I think is an eprom from a board. The chip is an OKI M2764Z-N. It has no quartz window which causes confusion. I assumed so far that all 2764s were eproms. Can it be an eeprom?

Second question: I plan on building a simple eprom burner for 2764s,

27128s, 27256s. I would like it to use LPT1 under DOS (for simplicity's sake). Are there any projects on the web I can study to help me in my journey?

Third question: which junky old electronics am I likely to find these eproms in?

Thanks,

Reply to
micologist
Loading thread data ...

an

be

Of course. I forgot to put on my thinking cap before posting.

2764s,

simplicity's

my

I have. I only found one page with two projects: one parallel interface and another serial interface. Basically the same project but with revisions.

formatting link
Do you know of any others? I am not interested in building a willem programmer.

I will keep that in mind. No real sense in collecting them until I've built some kind of programmer.

I was thinking of building one with a germicidal lamp. If I can find a local supplier and they are cheap.

Thanks,

Reply to
micologist

simplicity's

my

Er. Ok I'm finding more. Ignore my gravely insulting use of newsgroups :)

Reply to
micologist

I haven't tried ot find the data sheet, but it is just as likely to be an OTP (one time programmable) EPROM. Eliminating the erasure window cuts the manufacturing cost way down.

You start with Google.

Anything with a old microprocessor (not a PIC or any of the newer units that contain the memory inside the processor. EPROMs go cheap on ebay. If you ask nicely, someone here will probably send you some. I have a few of some size in my desk drawer.

You should look for a small ultraviolet eraser, also.

--
John Popelish
Reply to
John Popelish

I suggest you use EEPROMs rather than UVPROMs - no need to worry about the UV lamp, or waiting for the chips to erase.

I've used Microchip 28C64 EEPROMs as replacements for 27C64s during program development.

--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
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Reply to
Peter Bennett

I am

on the

built

Ew. I have something similar in an old book. Definately not worth implementing.

project,

Thanks for the warning. I would have tons of old PCs to hook it up to. I wasn't planning on trying it on anything above more recent than a 486 (I'm not that thick).

I am going to look into eeproms instead...

Reply to
micologist

about

You're right. I should do everything possible to preserve my eyesight.

Thanks for the tip. I'll look into that.

Reply to
micologist

There seem to be a lot of derivatives of my EPROMr 2 floating about on the Internet.

The general design of the EPROMr 2 is actually based on programming algorithms used in an ancient, ancient totally hand-operated

2716/2732A/2732B programmer that I once saw in kit form (but never built because I didn't feel the urge to set up 1K of data on DIP switches).

I've been getting progressively more email over the years about PCs with which the design doesn't work. If you build it as a weekend project, and it works for you, great - but if not, it could turn into a very frustrating debugging exercise, I'm warning you now.

I built that project solely because I needed to repair and upgrade a few coin-op arcade game boards in my collection. I was experimenting with various patches to their ROMs, and I needed a quick and dirty burner that basically worked. EPROMr 2 was it.

The EPROMr 3 prototype and sourcecode were lost when I moved to America. It's most unlikely I will ever look at that project again, life's too short.

Reply to
Lewin A.R.W. Edwards

You're out of luck, unless you can find a friendly high energy physics lab that has an accelerator that can produce enough stray x-rays to erase them. ;-) These are OTP (One Time Programming) EPROMS. The most expensive part of the EPROM is/was the fancy package with the quartz glass window.

Steve Ciarci's old Byte magazine Circuit Cellar project books. Or Steve Walz's web/ftp site.

Older IBM clone keyboards. The ones with a XT/AT switch on the bottom. Circa 1985 they were usually a 8031 or 8039 single chip microcontroller with an external 2764 EPROM. Some used 8748 EPROM based microcontrollers, too.

If you have to punt and buy some, try Jameco or B&G Micro.

Mark Zenier snipped-for-privacy@eskimo.com Washington State resident

Reply to
Mark Zenier

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