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Duplicating Signetics Generic I based PROMs

I have a late 1970s designed peripheral for an Apple II, and am in the proc ess of reverse-engineering the peripheral and lay out a new PCB design. On the card, it uses an Intersil IM5623 PROM. It is a 256 x 4 bipolar PROM, an d is programmed using the Signetics Generic I fusing procedure:

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I want to duplicate this PROM. I've spent hours reading on the subject. Wha t I've come to the conclusion is that although these PROMs can all be read one way or another, the challenge is programming them, as there is no set s tandard. I can try programming a Philips 82S129 or a Harris 7611, but each of the use different programming techniques, as well as possibly different voltages and such.

In my situation, however, I'd like to duplicate the IM5623 to another IM562

  1. Any pointers on how I can go about doing this would be great!

Also, if you're willing to offer your services, I have 20 unprogrammed PROM s I'd like to get programmed.

Thanks!

Reply to
groink1
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The Data I/O 29B with Unipak can handle those easily enough. I have that machine in Vancouver, Canada - but there are many still in the USA. I use my unit regularly for burning old PROMs and EPROMs.

There are probably others on this list who can help if they have a 29B. There is also the Data I/O mail list/group (Data_IO_EPROM) on Yahoo, you can post there and find someone handy to you I'm sure.

I have burners that go back to the 1702(A)...

John :-#)#

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Reply to
John Robertson

I would have replaced the prom with a PIC or AVR.... :)

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Reply to
TTman

That's possible, given that I'm redesigning the PCB. I'm not familiar with those two parts - I'm more into microcontrollers. Between PIC and AVR, what specific parts would be a good replacement?

Reply to
groink1

More information that might help....

After studying the schematic diagram I created of the peripheral, I've real ized that this PROM operates more as a TTL-based chip than just storing cod e. It merely acts as field programmed IC, much like for example a GAL or PA L. From what I can gather after studying the chip's operation, it basically performs high-speed data transfers between what could possibly be a mixtur e of RAM, EPROM and masked ROMs. At each cycle, the PROM does this, so it h as to be very fast. Even I was able to read the PROM (I found out how to ad apt this chip to a 2716 socket for reading,) all it is going to give me is microcode. And, from the very limited information I can find about bipolar PROMs, there's nothing available I could use to decipher the microcode so t hat I can reverse-engineer and re-write the logic, using for example a micr ocontroller like a PIC or AVR as someone earlier mentioned.

So the big hurdle at this point is to decipher the microcode. :(

Reply to
groink1

Can't help, but does the board still work?

Best regards, Piotr

Reply to
Piotr Wyderski

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