AT&T PC 6300 Revisited

[clh333]

I acquired an AT&T PC 6300 recently; it arrived yesterday. Having owned one back in the 1980s I am "sorta" familiar with it, but back then it was just an office appliance. The farthest I got into the hardware was to add a DTC controller and a Conner HD. I passed it on a few years later for a newer PC with 3.5 inch drives and a color display.

So now I have a survivor of that era, and I have gotten as far as removing the CPU's top cover. Already I am asking questions:

In addition to the video card and 2 half-height 5.25 FDDs there are two 8-bit cards in the backplane: One is a Plus HardCard 20, which I'm guessing is an HD on an ISA card.
Anyone got documentation for that?

The other card is a DAK VG-100 and appears to be related to video; there are two RCA jacks labeled video in and video out. No idea.
Anyone recognize this?

I know the motherboard is upside-down under the backplane that holds the cards and that the video card is a connector for the two. I would like to check for dead battery and possible cap leaks.
Can I remove the bottom-half cover or will I have to remove all the internal components to access the motherboard?

The keyboard is missing one key cap and switch (lower right corner, RETURN as I recall).
What is the switch mechanism, and does anyone know of a source for spares?

Thanks for your replies.

-CH-

Pics:

 

[1ST1]

Yes, the mainboard is "downstairs" and you have to check the battery. The keyboard is special, you won't get spare parts for it, except of from another same keyboard. The Plus HardCard 20 should be a harddisk (so called filecard), I guess it is having 20 Megabytes, but that is not original AT&T/Olivetti part, but some kind of third party add on.

You can download all service manuals etc. from the following sites:
- https://sites.google.com/site/att6300shrine/Home
- http://www.olivettim24.hadesnet.org/download.html

Please note, that AT%T 6300 is originally an Olivetti M24. And Xerox 6060 and Logabax Persona 1600 are the same as well. So you can use software, drivers, manuals, etc. from all of them to learn about this machine.
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[lambda84]

Can't say much about those cards, but to access the underside, just remove the two captive flat head screws on the back bottom corners and the bottom part of the case should slide off. To remove the motherboard, remove the screws and standoffs holding it in place, take out the video card that came with it, and I believe unscrew the thick red and black power cables, and the it should come out without a problem. I don't think much is on the underside of the motherboard, so just removing the bottom case should reveal everything you want to check without taking out the whole board.

 

[clh333]

Yes, the mainboard is "downstairs" and you have to check the battery. The keyboard is special, you won't get spare parts for it, except of from another same keyboard. The Plus HardCard 20 should be a harddisk (so called filecard), I guess it is having 20 Megabytes, but that is not original AT&T/Olivetti part, but some kind of third party add on.

You can download all service manuals etc. from the following sites:
- https://sites.google.com/site/att6300shrine/Home
- http://www.olivettim24.hadesnet.org/download.html

Please note, that AT%T 6300 is originally an Olivetti M24. And Xerox 6060 and Logabax Persona 1600 are the same as well. So you can use software, drivers, manuals, etc. from all of them to learn about this machine.
-

Thanks for your reply.

I know (now) that the 6300 was a re-branded Olivetti. I had never seen the add-in cards contained within and still don't have any idea what the DAK card was for, but apparently somebody listed another one on eBay for $200. I'm pretty sure he doesn't know what to do with it either.

I have a bad habit of saving useless stuff for "someday" so I have the original manuals for the AT&T and also the original distribution disks, containing MS-DOS 3.x and the AT&T utilities and help files. Including the mouse driver there are eight disks in all. So I diskcopied the boot disk and booted the machine; all systems passed POST. So far, so good.

Thanks again for your input.

-CH-

 

[1ST1]

Anyhow, check the battery and take it out. It only holds the date/time, nothing more. But these batteries tend to leak and destroy the board.

 

[Chuck(G)]

Good Lord, a DAK board--from Drew Kaplan during his heyday, nonetheless. I used to love to browse his catalogs and actually bought some stuff from him back in the day. Here's a sample catalog

The VG-100 card doesn't ring any bells, but you can drop a line to Sol (who took over from Drew when he retired) at dak.com. If Sol doesn't remember, maybe Drew will.

 

[clh333]

Good Lord, a DAK board--from Drew Kaplan during his heyday, nonetheless. I used to love to browse his catalogs and actually bought some stuff from him back in the day. Here's a sample catalog

The VG-100 card doesn't ring any bells, but you can drop a line to Sol (who took over from Drew when he retired) at dak.com. If Sol doesn't remember, maybe Drew will.

I was wondering of that was the same company... the logo looked familiar. What the hell were they doing manufacturing PC cards?

I used to get their catalogs all the time, too. I probably bought something from them but I can't remember what.

Thanks for the link; I'll ask.

-CH-

 

[clh333]

Anyhow, check the battery and take it out. It only holds the date/time, nothing more. But these batteries tend to leak and destroy the board.

Motherboard Rev. P4, ROM Rev. 1.43, 8087 on board, battery had leaked but perhaps not enough to damage the traces.

Thanks for your assistance.

-CH-

 

[Chuck(G)]

Fortunately, the battery is "upside down", which makes it a bit more likely that leakage will affect the motherboard less than in "normal" designs. I replaced mine with a lithium coin cell in series with a schottky diode (lower forward drop than a normal silicon diode). Works just fine.

 

[clh333]

Fortunately, the battery is "upside down", which makes it a bit more likely that leakage will affect the motherboard less than in "normal" designs. I replaced mine with a lithium coin cell in series with a schottky diode (lower forward drop than a normal silicon diode). Works just fine.

Good to know, although I will do without the battery for now.

Found that Plus Card 20 was the second offering from a wholly-owned Quantum subsidiary who pioneered the drive-on-a-card product in the mid-80s. Found a link to some docs and software utilities here: http://ibm-pc.org/firmware/other/plus%20hardcard/plus%20hardcard.htm. Appears I have BIOS version 5.x; second version of the board.

No reply from Sol or DAK yet.

Thanks,

-CH-

 

[clh333]

Good Lord, a DAK board--from Drew Kaplan during his heyday, nonetheless. I used to love to browse his catalogs and actually bought some stuff from him back in the day. Here's a sample catalog

The VG-100 card doesn't ring any bells, but you can drop a line to Sol (who took over from Drew when he retired) at dak.com. If Sol doesn't remember, maybe Drew will.

I heard from Drew Kaplan who was kind enough to respond,

"Hi Charles, So I think it was my PC Soul Snatcher video grabber card. I’ve attached a black and white close out ad. I’m sure I have the color somewhere, but this will explain what it did.

Have a great day

Drew".

Essentially this is a 256x256 greyscale digitizer board. The DAK ad is attached.

I also found threads in the VCF archive discussing the Plus 20 Hardcard. Like others I was getting, after a long pause, a controller error, indicating that the BIOS was functional but there was some problem with the drive mechanics. I disassembled the drive and found the gooey stop that others had found. I cleaned the post and replaced the rubber with a bit of heat-shrink tubing, then reassembled and reinserted the card. This time I quickly got a different error. The drive now sleeps with the fishes.

-CH-

Ad:

 

[blaknift]

I finally got my 6300 That I have been waiting since early April for. I'm going to build a VGA adapter cable and see if It will output video to an old CRT. Mine is in fantastic shape, And someone had taken the battery out long ago and added wires out of the front of the case to hook one up! Thing is an absolute beauty inside.

Mine also came with a hard card! Western Digital Filecard20.

Is what i'm seeing next to the floppy drives another Hard drive?

I just gotta find a keyboard for this damn thing....Lol

 

[1ST1]

It looks like it has the Toshiba floppy drives. They are 80 tracks DD. Officiallly Olivetti sold them as 640 k drives (8 sectors, 80 tracks, double sided), but they are also capable for 9 sectors (720 kb). I have the Olivetti Service manual for these drives. You only need to set the dip switches for these drives (80 tracks) and use driveparm to tell it about the 9 sectors.

 

[clh333]

Is what i'm seeing next to the floppy drives another Hard drive?

Looks like it, although I've never seen that arrangement / case. But this is where I intend to put an HD when I get that far. Having the two 5.25 drives is not something I want to sacrifice.

Anyone familiar with this setup?

-CH-

 

[Trixter]

I would like to check for dead battery and possible cap leaks.

Please remove the battery; it only holds time and is not necessary for operation of the system. (The clock used only 8 bits for the year anyway; it only keeps time from 1984-1992, then rotates around again)

Can I remove the bottom-half cover or will I have to remove all the internal components to access the motherboard?

Consult the documentation; the bottom half is removable separate from the top half. It slides forward.

What is the switch mechanism, and does anyone know of a source for spares?

The key switch mechanism was unique (it's not buckling spring, ALPS, Cherry, etc.). You must get spares from another keyboard or an Olivetti M24 keyboard.

Looks like it, although I've never seen that arrangement / case. But this is where I intend to put an HD when I get that far. Having the two 5.25 drives is not something I want to sacrifice. Anyone familiar with this setup?

Yes, this was common for people adding hard drives to a 2-drive setup. In the AT&T 6300 Retrospective video, you can see a third variant, someone who cut a hole into the case to use the side bracket as a 3rd floppy drive.

 

[Chuck(G)]

Mine came with an 80MB hardcard (although not the Quantum brand).

 

[clh333]

As I mentioned earlier the Plus 20 card has been abandoned as FUBAR. The plan is to try to get a SCSI drive installed in the space next to the FDD cage. I obtained a Seagate ST01 8-bit controller for that purpose; I have a 170 Mb Quantum with a 50-pin SCSI I interface that I would like to use with it.

The hard card would have been an easy solution but apparently the early ones weren't all that robust.

-CH-

 

[Stone]

I have a Quantum 170MB hardcard if that's of interest (Sorry, I see that's a 16-bit ISA card).

I also have a Seagate ST-238R drive/WD 1002-27X controller combo that I think I removed from a dead 6300 15 or 20 years ago. Anyway, it's running fine and already configured so it's basically plug'n play. :smile:

 

[1ST1]

If you swap to another drive I would sugest to go for XT-CF controller.

 

[clh333]

Thank you for your offer but there would be no room for anything else in the drive bay with the full-height ST-238 installed.

-CH-