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Writing new roms in eproms for the PET

D

Daan Muller

Experienced Member
Joined
Feb 17, 2026
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50
I need new roms for my 2001-N32.

I have found the correct .bin files for the 2 basic, the editor and the kernel rom. They correspond with the numbers on the faulty roms in the PET.

I have a T48 eprom programmer and using the pc laptop from one of my sons (I use Mac myself) I can read the TMS2532-A eproms I have and I can write what it read back again also.

But when I load and try to write one of the .bin files I get this error: ERROR! Adress:0X000000 Buffer Data 0x40 Verify 0xFF

I have no real clue what the problem is, but I think it has to do with the address it needs to write to or the size of the .bin? But this is all technically above my pay grade really.

Any help would be appreciated.
 
OK, I think I need to make an adapter to reroute some pins so that I can use the 2732 setting on the T48 to program the 2532.
 
I have an older BP Micro Systems EP1 Programmer that will easily program those EPROMS.
If you have the TMS-2532 EPROMS that are erased it won't take long to program them.
I hope you haven't corrupted them by trying to program them.

If you would like me to try Programming I will need your files and the EPROMS.

I only charge for return postage.

Larry
 
I have mentioned a few times the TMS2532-A roms are to be avoided, that is if you want to avoid trouble. I think there are a few good NOS (unprogrammed ones) out there, but these IC's being the 21V programming parts are notorious for giving trouble. Though, I'm sure if you had the BP Microsystems BP1400 and an unused/never used TMS2532-A they would be just fine. These parts have caused afew headaches in the video game industry too.

There are a couple of potential issues:

The first one is that a number of modern programmer tools either do not support or fail to program the "A" suffix parts, for this I have no explanation at all, except probably the manufacturers must not as been as thorough or smart as those who built a programmer like the BP1400. But also I think a lot of the trouble with the "A" parts relates to their history. I think what happened in many cases, after they were brand new, they got accidentally programmed with the 25V programming voltage along with the non A suffix parts. This works the first time, but on later attempts with erasure & re-programming it fails.

So as I have always said for the PET, keep away from the "A" suffix parts, always use the plain TMS2532JL part and get NOS unprogrammed ones helps too, and if you want to avoid headaches from adapaters, avoid the 2732 and the 2732-A while you are at it.

If, when you have a NOS never programmed TMS2532JL or a few of them, and your programmer fails to program that, your programmer is defective. A GQ-4x4 programs a TMS2532JL perfectly, as does the BP1400.

Be aware also that if there is a borderline cell somewhere in the rom, it is still possible for it to pass a blank test and apparentlty program normally with one .bin file, but with another .bin file with a different byte (or bit) at the location, it can fail. Your experience suggests this is what is happening with the TMS2532-A. Create a file of all loacations "00" and use that to test program your TMS25232-A it may simply fail at the same initial address, then erase it and see if it all goes to all FF.

I've got a feeling there is a programmer model out there that has a penchant for fouling up the first byte in a file, I cannot recall if it was the T48, maybe somebody will remember.
 
Last edited:
ldkraemer said:
I have an older BP Micro Systems EP1 Programmer that will easily program those EPROMS.
If you have the TMS-2532 EPROMS that are erased it won't take long to program them.
I hope you haven't corrupted them by trying to program them.

If you would like me to try Programming I will need your files and the EPROMS.

I only charge for return postage.

Larry
Click to expand...
I have an adapter on the way that should let me program the 2532, if this doesn't work out I will gladly take you up on your offer.
 
Hugo Holden said:
I have mentioned a few times the TMS2532-A roms are to be avoided, that is if you want to avoid trouble. I think there are a few good NOS (unprogrammed ones) out there, but these IC's being the 21V programming parts are notorious for giving trouble. Though, I'm sure if you had the BP Microsystems BP1400 and an unused/never used TMS2532-A they would be just fine. These parts have caused afew headaches in the video game industry too.

There are a couple of potential issues:

The first one is that a number of modern programmer tools either do not support or fail to program the "A" suffix parts, for this I have no explanation at all, except probably the manufacturers must not as been as thorough or smart as those who built a programmer like the BP1400. But also I think a lot of the trouble with the "A" parts relates to their history. I think what happened in many cases, after they were brand new, they got accidentally programmed with the 25V programming voltage along with the non A suffix parts. This works the first time, but on later attempts with erasure & re-programming it fails.

So as I have always said for the PET, keep away from the "A" suffix parts, always use the plain TMS2532JL part and get NOS unprogrammed ones helps too, and if you want to avoid headaches from adapaters, avoid the 2732 and the 2732-A while you are at it.

If, when you have a NOS never programmed TMS2532JL or a few of them, and your programmer fails to program that, your programmer is defective. A GQ-4x4 programs a TMS2532JL perfectly, as does the BP1400.

Be aware also that if there is a borderline cell somewhere in the rom, it is still possible for it to pass a blank test and apparentlty program normally with one .bin file, but with another .bin file with a different byte (or bit) at the location, it can fail. Your experience suggests this is what is happening with the TMS2532-A. Create a file of all loacations "00" and use that to test program your TMS25232-A it may simply fail at the same initial address, then erase it and see if it all goes to all FF.

I've got a feeling there is a programmer model out there that has a penchant for fouling up the first byte in a file, I cannot recall if it was the T48, maybe somebody will remember.
Click to expand...
These TMS2532-A come from a reputably pinball supply shop here and should be NOS. I can read them with the T48 set to 2732 and they read all FF. I will see what happens with the adapter board that lets me program them as 2732. It should work out with the voltage as the T48, although they say it does 25V, in practice puts out 21V from what I have read.
 
Hugo's experiences and words around the Motorola TMS Series EPROMS can be relied on,
as he knows Hardware.

I've had good experiences using the BP Micro Systems EP1 for more than 20 years at work,
using the Motorola TMS 25 Series EPROMS. In fact my Radio Shack Model 1 has them installed
with Version 1.3 ROMS. Still good EPROMS that work fine. I still have a few TMS in my stash.

Larry
 
>>> ERROR! Adress:0X000000 Buffer Data 0x40 Verify 0xFF

The programmer failed to either write the original data to the EPROM or failed to correctly read the information it wrote.

The expected data byte for address 0 should have been 0x40 but was read of 0xFF.

0xFF is the same value as an erased EPROM. It is also likely to be the value that is read by the programmer if the EPROM is not (actually) being read.

When programming (and verifying, reading) an EPROM - the programmer and device need to match. Sometimes, the programmer purports to support a device - but doesn't! Go figure...

A 2532 is not the same device as a 2732 - and there are different variants of each device...

Dave
 
Daan Muller said:
These TMS2532-A come from a reputably pinball supply shop here and should be NOS. I can read them with the T48 set to 2732 and they read all FF. I will see what happens with the adapter board that lets me program them as 2732. It should work out with the voltage as the T48, although they say it does 25V, in practice puts out 21V from what I have read.
Click to expand...
Opps, no for three reasons:

1) reading all FF means nothing at all, it just means all the data is high and that can simply be due to pullups in the programmer.

2) the pinball industry is awash with recycled ROM parts.

3) But mainly you cannot set theT48 (or any programmer) to a 2732 and hope to program a TMS2532A on an adapter, the 2732 has a 25 V Vpp, the TMS2532A has a 21V Vpp. This is exactly what I was saying happens to a lot of TMS252A's out there, they get damaged with 25V Vpp applied and then become unreliable and they ay already have been subject to this dilemma. If there is any doubt about the T48 not being able to program 25V parts, I'd not even consider using it in a PET repair scenario. Any decent programmer lets you select either the 25V or 21V (A) parts without ambiguity, and if there is any ambiguity, the programmer should head to the rubbish bin.

If you plan to use a "2732" setting on any proper programmer, to attempt to program a TMS2532A (on an adapter) the programmer itself must be able to support a "2732A" and you had better select that option in the device list, or your 2532A will end up in La-La land along with many others.

If you listen to what I have advised here; a) use the TMS2532JL (not the TMS2532A) b) keep away from adapters and 2732's, you will eliminate two variables here both of which could give you a headache, and if it were me, I'd not use the T48, I'd use a GQ-4x4, which is known to 100% support the TMS2532JL without question and be non-buggy, eliminating a third variable.

With a lot of vintage stuff it is all about eliminating variables and potholes that will trip you up, and going with known good solutions, or simple problems could keep you running in circles, like the song Mad World.
 
Just for the record: I successfully programmed a bunch of TMS2532JLs (and one 2716) for my PET/CBM 3032 with a T48 using a 2732 adapter and a pretty cool open-source command-line tool called minpro (https://gitlab.com/DavidGriffith/minipro), which allows you to explicitly set Vpp. The invocation I used was
Bash: 
minipro p '2732@DIP24' -w path/to/rom.bin -o vpp=25
Cheers -- track18
 
Still waiting on the circuit boards for the adapter I ordered from china.

In the meantime it occurred to me that the roms probably are allright and it's just a question of reseating them (as with the 6522's) in the white holders. I did have the 24 pin ic sockets so I put the 2 roms with the 3 missing legs between them in ic sockets and soldered the missing legs to the ic sockets. And presto, the machine is working 100% now without the RAM/ROM board. :)
 
Is it somehow possible to edit a post? It seems I forgot a leading dash in front of minipro's p option. The actual invocation was
Bash: 
minipro -p '2732@DIP24' -w path/to/rom.bin -o vpp=25
Cheers -- track18
 
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