AT&T PC6300 ROM variations

[clh333]

In 2020 various members discussed "AT&T PC 6300 BIOS 1.1 ROM dump" and the point was made that merely updating ROMs would not suffice, as there were differences in the motherboard components as well. One of the respondents, Trixter, mentioned that he had to replace 2 PALs to bring his 1.21 ROM machine up to 1.43.

As I am contemplating the same update on a 1.21 machine, may I ask: Which PALs and where did you locate them?

-CH-

 

[modem7]

Which PALs ...

The thread [here] that you refer to includes, "You can read about this in the pocket service guide chapter 1.".
That guide is probably the 'Pocket Service Guide - Volume 1 - 6th Edition' at [here].

 

[clh333]

Thank you once again modem7; I am continually impressed with the breadth of your endeavors.

-CH-

 

[1ST1]

Yes, that's it, these PALs have to be replaced / reprogrammed, oderwise the M24 doesn't work properly with the new BIOS. Unfortunately there is no download ressource for the programming files, so they must be copied from working machine (I think PAL chip has no copy protection). Maybe that would be a nice little project to save these PAL files and put them somewhere online, at 6300 shirine for example, Trixter ???

When trying BIOS 1.43, why not just try the quite unknown version 1.44? I was able to get it from a M21 which was sold in eBay, and since then I saw another M21 in eBay having Bios 1.44 as well. This version is quite rare, but maybe specially could be found sometimes on M21 machines. I have tested with my M21 (which came with BIOS 1.36) and it runs well.

 

[clh333]

Yes, that's it, these PALs have to be replaced / reprogrammed, oderwise the M24 doesn't work properly with the new BIOS.

Another rabbit hole. I have another 6300 bearing the 1.43 ROMs. Presumably it is equipped with the special PALs as well. Dumping the content of a PAL is terra incognita for me, however.

-CH-

 

[Trixter]

The new PALs are not always needed, which is based on my experience as a teenager: I got the ROM 1.43 BIOS upgrade, which came with the PALs, but I put the new PALs in backwards (a mistake) and they burned up so fast that the labels on them turned brown in less than 10 seconds. They were fried, so I put the old 1.21 PALs back. I ran the system successfully after that for several years, with the 1.21 PALs and the 1.43 ROM BIOS.

Keep in mind that it is possible I ran into issues but simply don't remember them. But I did the upgrade in 1988, and continued to use the system as my primary computer until late 1990. I remember the ROM BIOS 1.43 upgrade was necessary to use Microsoft Word 5.0 in the 640x400 AT&T graphics mode, and after my franken-upgrade, it did indeed work.

 

[clh333]

I have another 6300 bearing the 1.43 ROMs. Presumably it is equipped with the special PALs as well. Dumping the content of a PAL is terra incognita for me, however.

Attached are pictures of the above-mentioned 6300, which I purchased a few years ago and shelved due to display problems and other inconsistencies. The 1.43 low and high ROMS are on 28-pin DIP ceramic Intel D2764A-2s; should be easy to copy as they are socketed. There are two ICs identifed as PALs; one is MMI PAL12L10CNS and one is NatSemi PAL14H4NC. Replacement ICs for both are currently available, both ICs are socketed as well.

The next issue then is: Can these be read by an EPROM reader, and if the file can be captured can a like IC be burned from the source? I don't know anything about this process; I defer to the experts.

-CH-

 

[1ST1]

There are special PAL/GAL programmer available, and there are (E(E))PROM/Flash/...-programmer available which have the correct adapters to support also PAL/GAL chips (PAL and GAL ist not exactly the same). Currently there is a device on eBay which supports to program about 12-13.000 chip , GAL is listed in the Offer, PAL not. The same device is also available on Alibaba for 1/3 lower price. If I knew it can support PAL I would think about to order one. It's name is "TL866II Plus".

 

[clh333]

Currently there is a device on eBay which supports to program about 12-13.000 chip , GAL is listed in the Offer, PAL not. The same device is also available on Alibaba for 1/3 lower price. If I knew it can support PAL I would think about to order one. It's name is "TL866II Plus".

There are also duplication services but from what little I know they are prohibitively expensive. A few years ago I purchased the precursor model, TL886CS, from an eBay seller. It turned out to be counterfeit and XGecu refused to support it but I have written to the company asking for details on this model. When and if I hear from them I will report my findings.

-CH-

 

[tpaxia]

Attached are pictures of the above-mentioned 6300, which I purchased a few years ago and shelved due to display problems and other inconsistencies. The 1.43 low and high ROMS are on 28-pin DIP ceramic Intel D2764A-2s; should be easy to copy as they are socketed. There are two ICs identifed as PALs; one is MMI PAL12L10CNS and one is NatSemi PAL14H4NC. Replacement ICs for both are currently available, both ICs are socketed as well.

The next issue then is: Can these be read by an EPROM reader, and if the file can be captured can a like IC be burned from the source? I don't know anything about this process; I defer to the experts.

-CH-

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I recently acquired a very clean AT&T 6300 with keyboard, monitor and bios 1.1. Since at some point I would really like to make or get an APB-Z8000 board for it, I also got an M24 with 1.43 just to get the new PALs. I also have the TL866II Plus. When I pick up the 6300 next week I can try to read the PALs and compare them.

Which replacement IC have you found?

Thanks!

 

[clh333]

I recently acquired a very clean AT&T 6300 with keyboard, monitor and bios 1.1. Since at some point I would really like to make or get an APB-Z8000 board for it, I also got an M24 with 1.43 just to get the new PALs. I also have the TL866II Plus. When I pick up the 6300 next week I can try to read the PALs and compare them.

Which replacement IC have you found?

Thanks!

I applaud your enthusiasm. I would point out that it is possible for a PAL to be "protected" but I don't know what "protected" means and I also don't know if the Olivetti PALs are protected in any way.

The replacement ICs are available from eBay USA listings; search by the chip designations.

-CH-

 

[tpaxia]

I applaud your enthusiasm. I would point out that it is possible for a PAL to be "protected" but I don't know what "protected" means and I also don't know if the Olivetti PALs are protected in any way.

The replacement ICs are available from eBay USA listings; search by the chip designations.

-CH-

Well, these are small devices and pretty simple: nobody can stop you from extracting the maps by brute force and then derive the equations. I thought that it would be easier to replace them with more modern GALs and not by getting old stock OTP PALs...