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Wanted: bus correction kit for AT&T 6300 (Olivetti M24)

Chuck(G)

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I guess--it just offends the purist in me. Sort of like using a 74LS381 as a quad-AND gate because the drawer that holds my 74LS08s is empty and because I have a lot of 381s.

If that's what you want to use, however, don't let me stop you. In that case, perhaps you should figure out the contents of the original 82S123 and include that in the selections.

OTOH, how many of these things are going to be made? If it's not many, I probably have enough TBP18S22 bipolar PROMs (256x8 ) to satisfy demand. Heaven knows, I'm never going to use them.
 

keepiru

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Feb 2, 2009
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Our planned production is currently one unit for digger. :) I'll publish the gerbers so anyone can make one if they want, but I figure no more than five will ever be made. This is a pretty tiny niche.

I'm not set on any design. My question is just because I love learning as I go along. It's often educational and always at least interesting to find out why one technology is chosen over another.

In this case I just want something that will probably work, that we can easily try a new image without creating new boards if it fails, and that parts will be available for a few years for those two or three people who want to build one in the future.
 

Old Thrashbarg

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I'd like to make one as well, but I'm personally inclined to forgo the PCB and just throw it together on a piece of stripboard. It should work just the same and I don't really care what it looks like anyhow.

The issue for me is probably going to be programming the chip itself... the only sort of programmer I have is one of the basic Willem things, which of course won't do PROMs or GALs. Perhaps I'll try building one of the GALBlast designs that are floating around out there...
 

Chuck(G)

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Well, it's simple enough to wire one up whatever way you want, since you now have the contents of the ROM. I'd had the idea to use SMT parts and wire the thing on the bottom of the of the bus converter board, replacing the existing ROM socket. Just a couple of jumper wires out to the 16-bit connectors and you've got an "invisible" mod. Or make a tiny board that plugs into the ROM socket with SMT and simply run a couple of wires from that to complete the picture.

No matter how you do it, it's pretty easy.

It is possible to build a bipolar PROM programmer that's manually operated with very few parts.
 

keepiru

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Yeah, but it's got me wondering...

...

Sorry for the thinking, but I'm trying to make sense out of this one.

So, did wondering turn anything up any sense?

I'll be running a panel soon, so I need to know what's going on it. :)
 

Chuck(G)

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As far as I can determine the choice is not between original and modified, but between two different versions of "modified". I suppose that if you wanted "original", you'd just plug the original PROM in.

Which reminds me--has anyone dumped the original PROM yet? Seems that I've done my part in this and would like to have an original PROM (or at least the contents thereof) for my own machine.
 

keepiru

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It looks like I'll have some space on a panel I'm sending off tomorrow. Can you confirm that the final arrangement from post #48 will work?
 

Chuck(G)

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It looks like I'll have some space on a panel I'm sending off tomorrow. Can you confirm that the final arrangement from post #48 will work?

It should, but I haven't tried it. You could also simply duplicate the bipolar PROM that I posted if you were squeamish. Doesn't look like there's a lot of interest in this.
 

yuhong

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Mar 2, 2010
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337
Well, if one or the other jumper setting is best, we can cut down on the complication and fit the whole thing into a GAL16V8, 20 pin chip, which is considerably easier to find than the GAL22V10.
Well, from https://groups.google.com/group/comp.sys.att/msg/4efbd333e2adb978 :
"There is a switch on the Buss Correction Board that will increase the
bus speed 10 - 30 % more then the AT&T standard, but haven't had everything
run long enough to try this yet."
Probably referring to the fact that the ISA bus on the 6300 runs at 4Mhz not 8Mhz.
 
Last edited:

digger

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Great job!

Great job!

Again, thank you all, Chuck(G) and keepiru in particular, for helping me out with this! :)

And sorry I haven't replied to this thread in awhile, even though I was the one who initially made this request. :blush:

@keepiru: If I read back correctly, you had a panel manufactured back in June? How did it go?

I'll be happy to reimburse any of you for any costs incurred with reverse engineering the bus correction kit, as well as for having one manufactured and shipped to me.

But I guess with the board schematics and GAL programming code that you both posted in this thread, I should be able to either recreate one myself or have one made more locally, right?

To be clear: would I be the first person to actually try out one of the reproduced kits?
 

digger

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The bus correction kit requires software too?

The bus correction kit requires software too?

Hey, I just something interesting and seemingly important in the Usenet thread that one of you linked to previously:

The Paradise Card came with two floppies full of drivers, docs, and programs. Only problem with the executables was they didn't work on my 6300, machine would just stop. This included a test program for ROM BIOS and a 16 bit bus, so I expeceted problems. The software that came with my Buss Correction Board did the trick though. Executing it in my autoexec.bat allowed my EGA and VGA programs to run great.
(Source: https://groups.google.com/forum/?fromgroups=#!msg/comp.sys.att/6ej1hhkg2uI/eLmt4jPT-04J)

Apparently, the EGA/VGA compatibility fix requires some software to be loaded in addition to the bus correction board being installed.

@Chuck(G), your ATT6300 came with such a bus correction kit, right? That's what you used to reverse engineer it in the first place. Did your 6300 by any chance come with such software?

Or perhaps someone else reading this has an M24 or an AT&T 6300 with a bus correction kit, and happens to still have the software for it as well?

It would appear that there is perhaps yet another puzzle piece that we still need to get this to work...
 

keepiru

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Feb 2, 2009
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Oh hey, sorry for the late response. Life happened.

Yes, they physically exist now. The boards have been sitting on my workbench and I just haven't had a chance to go get the appropriate sockets and solder them up.

Pics or it never happened: 6300.jpg

Nah, I don't need money for this. This is just for fun. :)

And yes, you'll be the first one to try these out. Hopefully the magic smoke stays in.
 

keepiru

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Feb 2, 2009
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digger: I PMed you for your mailing address. Ping?

I have one built and waiting. I just need to know where to send it.
 

digger

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Hi keepiru,

I'm so sorry I hadn't replied for so long! Work and other stuff kept me away from the forum.

I replied to your mail.

Thanks again for both your help, and your patience. :)
 

pietja

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Oct 28, 2014
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97
Location
Amsterdam, The Netherlands
First let me say i know its an really old tread.
But i'm also looking for this bus correction kit.

I really appreciate all the work keepiru and Chuck(G) put into it.
With all the info in this tread i would be able to make one myself but a real board would be better ;)

To give something back for all the effort that went into it i have dumped the contend of the original PROM (82S123 - PQB1) on the bus converter.
Code:
00000000  F3F3 F3DB D8D8 98D8 DCD9 DBD3 D2D2 9242  óóóÛØؘØÜÙÛÓÒÒ’B
00000010  F3F3 F3D1 D0D0 90D0 4444 4444 4444 4444  óóóÑÐÐ.ÐDDDDDDDD
 

Attachments

  • PQB1.zip
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