Has anyone used 74S287 Proms in a Mimeo or Newton

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Joined: Oct 9 2011
Posts: 1044

I'm trying to figure out which Proms are compatible. I don't trust cross reference stuff when it comes to the A-1 design. It can be finicky.

Right now my list is MMI 6301-J and Signetics 82S129

thanks,
Corey

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Joined: Jun 5 2008
Posts: 380
Re: Has anyone used 74S287 Proms in a Mimeo or Newton

The Fairchild 93427 work

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Joined: Aug 24 2013
Posts: 45
Re: Has anyone used 74S287 Proms in a Mimeo or Newton

There are multiple different types of the 74S287. There are at least TI, National Semiconductor, and Tesla parts with the same designation. All three use different programming methods which are not compatible. Most US made programmers which claim to program the 74S287 appear to program the National Semiconductor parts.

I have a homemade programmer that I used to program the TI parts.

The TI parts work without issues in the Mimeo in which I have placed them.

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Joined: Oct 9 2011
Posts: 1044
Re: Has anyone used 74S287 Proms in a Mimeo or Newton

Christopher,

You seem to have done a bunch of research into these proms. I have a Data IO 29B with a Unipak 2b programmer. It says it supports the National Semiconductor 74S287 chips. So once programmed, are these chips electrically compatible with the TI parts you use?

Proms have gone up a lot since the last time I bought a bunch blanks and I'm about to buy a big lot of them so if they don't work it will hurt in my wallet.

Thanks for any advise,
Cheers,
Corey

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Joined: Oct 9 2011
Posts: 1044
Re: Has anyone used 74S287 Proms in a Mimeo or Newton

Well took a shot and ordered a bunch of ceramic National Semiconductor 74S287 chips.

Cheers,
Corey

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Joined: Aug 24 2013
Posts: 45
Re: Has anyone used 74S287 Proms in a Mimeo or Newton

Corey,

I expect that you won't have any problems with them. Although the timing specifications are slightly different between the parts, mostly in the max/min, the typical timings are very similar.

I didn't pay much attention to the operating specifications, as I was more focused on the programming of the parts.