82S129 & 82S137 Proms for a decent price? Why so much $ for them?

Thomas

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82S129 & 82S137 Proms for a decent price? Why so much $ for them?

Man these are to expensive, where can I find some of these proms at a better price than bobs 7.50 each?
 
That's a little better... Still not cost effective to switch over pp1 boards to pp2 once you figure in all the other stuff you need.

Hum these boards might be staying pp1...

Thanks for the post
 
Why so much? Nobody makes them anymore.

Any that you can find is a rare find. I have a couple of tubes of each and ask more than Bob does for them.
 
Why so much? Nobody makes them anymore.


...and more importantly, these proms are one-time use only,
unlike eproms which can be re-used.

Since most of these proms have not been produced in over 25yrs,
finding NOS supplies is becoming very difficult indeed.

I've also noticed a fairly significant price hike in common eproms too.

A few years ago, you could find several lots on eBay for reasonable prices,
but now most auctions range from $2-$5 per eprom (plus shipping).


Steph
 
I've had shit luck buying fuse link PROMs from eBay and surplus parts houses and now only buy them when I can see them in person. Too many people sell ones that have already been programmed.
 
I just got a real nice price on some N82S126 but unfortunatly they only had one tube of them.
Is there any alternative to these proms? Surely there is something modern that can be piggybacked on an adapter pcb to replace these.
 
I have many tubes of a 512 x 8 PROM which can be used on some boards to replace the 256 x 8 PROMs. All you do is tie the uppermost address line to ground and program the lower half OR tie it high and program the upper half.

I just wish I had many more of the 32 x 8 ones.

RJ
 
I just got a real nice price on some N82S126 but unfortunatly they only had one tube of them.
Is there any alternative to these proms? Surely there is something modern that can be piggybacked on an adapter pcb to replace these.

What about GALs and PALs? I know years ago I had Mark UK burn me some PALs to replace some PROMs on Pole Position.

Edward
 
Learn me something - is there any reason an eprom can't replace these proms, kinda like space invaders?

Speed.

Most PROMs are 35 to 55ns in speed and EPROMs are much slower. There's also the issue of board space. It's difficult to shoehorn a .600 DIP packaged EPROM where you have a tiny 16 to 18 pin PROM.

ELutz said:
What about GALs and PALs? I know years ago I had Mark UK burn me some PALs to replace some PROMs on Pole Position.

There are a few things that can be replaced with GALs, but I've never tried them in that manner. The nice part about GAL and PALCE chips is that they can be erased and reused where PALs cannot.
 
What about GALs and PALs? I know years ago I had Mark UK burn me some PALs to replace some PROMs on Pole Position.

Edward

This is interesting do you remember what kind of pals they were and for what location?
 
What about GALs and PALs? I know years ago I had Mark UK burn me some PALs to replace some PROMs on Pole Position.

Edward

For extreme majority of PROM's - a GAL won't work. The structure of a GAL is such that you have a large number of AND functions but a very limited number of OR selections on the output. Unless it is a VERY small PROM or only has a few changes per bit then the GAL won't work.

About the easiest way to describe this - think of a PROM as an array of OR gates all tied into an output with AND gates. Think of a GAL as an array of AND gates all tied to the outputs with OR gates.

Since you were able to replace a PROM on a Pole Position then that PROM must have had very little in it as far as changes per bit. As long as you can reduce the equations to ten "OR" functions or less, then it will work. Number of equations used depends on the actual PROM's original content.

Bipolar PROM's seem like they were always expensive - even a few years ago when you could still buy new ones in distribution.
Easiest way around it would be with EPROMS or OTP's... but these would require adapters.

Ed
 


I made up these new CPLD based PROM replacements for myself because I was sick of constantly searching for hard-to-find expensive NOS OTP PROMs and having to pay someone else to program them for me. I also have not been able to find and purchase a fuse-link programmer. Also, most such programmers are very picky and specific to the chip manufacturer. The programmers themselves are very old and finicky, even to the point of being unreliable. Another issue is that just because a chip is NOS, that doesn't mean that it will program or work correctly at all let alone the for the long term. After all, the chips are already 25+ years old.

The new PROM replacement modules are brand new flash memory based programmable logic devices and so are easy to source, relatively inexpensive, and they are reprogrammable using inexpensive modern equipment. They have been tested in Cinematronics CCPU boards, Tempest, and Battlezone. They should work fine in any board that uses any 16-pin bipolar PROM. All I have to do is convert the original binary file and then flash the new part. I created a custom Windows program that does most of the conversion work so it doesn't take me very long.

The BX288 part shown at this link replaces the 82S123 or 74S288 which is a 32x8 array.
http://www.biltronix.com/CCPU_Custom_Chip_Replacements.html#BX288

The BX287 part shown at this link replaces the 82S129 or 74S287 which is 256x4 array, and also the 82S131, 74S571 which is 512x4 array.
http://www.biltronix.com/CCPU_Custom_Chip_Replacements.html#BX287

Note that the new modules are not compatible with PROMs having open-drain outputs. They are however fully compatible with PROMs having tri-state outputs.

Bill B.
 
I have 2 programmers that do PROMs...

The ROMMax from eetools.com will program some... and the Data I/O Series 22 with the optional 351A-064 module will program most others.

Word of caution... the optional module on the Series 22 won't work by itself. You have to have the EPROMs with the software that install in the unit too.

RJ
 
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