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View Full Version : A video retrospective of the AT&T PC 6300



Trixter
March 28th, 2012, 07:17 PM
Viewable here: http://www.youtube.com/watch?v=mUCh46_MzZU

This was created for the gentleman who sold me the AT&T PC 6300 keyboard that got my system back up and running from the dead. He only requested a few pictures and some video of my restored system running, but I thought it would be neat to create a small tribute to the first personal computer my family owned. It goes into some detail, including a brief history of the machine, covers how it was better than the IBM PC it was a clone of, and provides some side-by-side comparisons of performance-intensive software running on both the IBM PC and the 6300.

The photos and video were obtained from my Samsung Epic 4G smartphone, which I regret, but I don't have access to better equipment. Some of the special high-res screenshots in the video were captured and converted from the real machine itself using software I wrote, PC Paintbrush's grabber TSR, and Pizazz Plus.

njroadfan
March 28th, 2012, 07:45 PM
Video quality was surprisingly good. I have a Samsung Droid Charge and find its 720p video pretty lousy in most lighting. The mic is worthless for audio however, so a voice over added in post is a must.

Trixter
March 28th, 2012, 08:04 PM
Video quality was surprisingly good. I have a Samsung Droid Charge and find its 720p video pretty lousy in most lighting. The mic is worthless for audio however, so a voice over added in post is a must.

A smartphone tripod adapter (and tripod) helped. Some of the macro shots were the setting the phone to macro mode and then manually focusing (ie. physically moving the entire camera closer/farther away) until it looked nice.

barythrin
March 28th, 2012, 08:17 PM
Dang Jim, great video! Love the comparisons and excellently put together and narration. Regarding the performance of the games at the end, I'm curious how you gathered the fps. Also was the only difference really the stock 6300 or was it running on your 30Mhz NEC (I know in the video you specified 8Mhz for the 6300). I'm kinda curious about other clones and their performance now.

Chuck(G)
March 28th, 2012, 08:17 PM
A very nice professional-looking video, Jim! :thumbsup: Is that 3.5" drive in the front a homebrew job? Mine still has the two 5" floppies (I recently replaced them with Mitsubishis because the latter has a slightly better build quality than the original). Mine has an 80MB Seagate hard card, rather than the standard WD controller.

The build quality is very high and the unit very compact, even if is a little weighty. It would be very interesting to find a Z8000 card for it; I'd also like to see if it's possible to get the Z8530 SCC going in that empty socket on the motherboard.

Of the early alternatives to the IBM 5150, I liked the NEC APC and the 6300 the most; when you got the 5150 fully fitted out, it ran you about as much as either the APC or the 6300. But no, I got a 5150 because it was more popular.

It was about 1984 that we decided to add another system to the VAX 11/750 we were already using. Since we were running BSD, another Unix box seemed logical. This wasn't that long after the '82 consent decree and AT&T had its sights set on becoming another big presence in the computer world. So I started by calling AT&T corporate sales and asking for prices and other information on the 3B5--it looked very promising. No one I talked to understood me--they kept shoving the 6300 my way. "We're buying a minicomputer, not a microcomputer" just fell on deaf ears. Finally, we just gave up after being promised callbacks that never materialized. We were pretty flush back then and could have dropped a hundred K without blinking. Nothing--AT&T just didn't understand how to sell computers.

Anyway, I enjoyed the video.

NeXT
March 28th, 2012, 10:30 PM
So windows was enhanced for the 6300.
Oh man, I wish I had properly stored mine. Now its just a paperweight. :(

Chuck(G)
March 29th, 2012, 08:00 AM
So windows was enhanced for the 6300.
Oh man, I wish I had properly stored mine. Now its just a paperweight. :(

Since I'm fairly familiar with these (and have one to compare notes with), I'd be willing to take a look at your board, if you'll pay shipping.

Great Hierophant
March 29th, 2012, 09:03 AM
Can the graphics chipset do anything in addition to the CGA modes other than 640x400x1 or 8x16 text boxes?

angel_grig
March 29th, 2012, 09:05 AM
Excellent video Jim and very professionally made!Lots of info I didn't know about the  AT&T PC 6300

Chuck(G)
March 29th, 2012, 09:11 AM
Can the graphics chipset do anything in addition to the CGA modes other than 640x400x1 or 8x16 text boxes?

Not following you exactly. Exactly what did you have in mind? BTW, I drive a VGA monitor with mine. Mostly a matter of a cable.

NeXT
March 29th, 2012, 09:22 AM
We'll talk privately.

Great Hierophant
March 29th, 2012, 09:51 AM
Not following you exactly. Exactly what did you have in mind? BTW, I drive a VGA monitor with mine. Mostly a matter of a cable.

Nevermind, the answer is here : http://www.seasip.info/VintagePC/cga.html

Awesome video btw. I have the same phone, so it is good to know that I can in theory produce a video of similar quality.

Chuck(G)
March 29th, 2012, 10:07 AM
Nevermind, the answer is here : http://www.seasip.info/VintagePC/cga.html

Olivetti/AT&T also offered a Video Enhaced adapter that fit the 16-bit slot next to the Display Adapter and attached with a ribbon cable that provided even more video modes. I've never seen one in the flesh, however. There was also an expansion chassis that fit as a "sidecar" on the basic unit.

Some motherboards had an extra jumper (H) to allow for a 10MHz 8087 instead of the normal 8MHz one. The floppy controller also appears to have support for 8" drives.

There's a lot of cool stuff lurking around in the innards of the 6300.

pearce_jj
March 29th, 2012, 10:39 AM
Interesting about the keyboard and mouse. The mouse was also connected to the keyboard on the RM-Nimbus PC186 IIRC, but it didn't have that extra functionality.

It's probably worth noting that the keyboard interface in the IBM PC was one of the few bits IBM did bother to patent, hence why many other machines had proprietory interfaces (Amstrad for example).

Ole Juul
March 29th, 2012, 11:52 AM
Good job on the video. :)

I recently discovered that I had a 6300 and one of these days I'll get into it. I just went and checked to make sure, because I was concerned about whether I had a keyboard. The one sitting with it has the right connector but it is a different unit. It says Key Tronic KB5151 Professional Series. I see it has some built-in lights too. I remember years ago having a keyboard with a similar connector and red letters. I've kept it around (deep in some box somewhere!) in the hopes that it would be useful some time. It looks like my haphazard collecting of the past will pay off with this system.

Chuck(G)
March 29th, 2012, 12:00 PM
Be careful with that keyboard--open it up and see if you see a 5V regulator (e.g. 7805) inside, as the keyboard is supplied with +12 from the 6300. I've got a keyboard (not Keytronic, but Advanced Input Devices) with the same connector, but if I tried plugging it in, it'd make magic smoke.

Trixter
March 29th, 2012, 07:56 PM
Regarding the performance of the games at the end, I'm curious how you gathered the fps.

I set up a tripod and shot video of both machines (separately, not simultaneously) and then synced the footage in the video editor. I was careful to choose games that had repeatable demo sections, so that there was something to sync up. The only one that doesn't have a repeatable sequence is Turbo Champions, which is why both halves don't look the same. As for calculating the FPS, I stepped through the video one frame at a time and counted how many unique frames were there, then divided by the length of the footage (number of seconds).


Also was the only difference really the stock 6300 or was it running on your 30Mhz NEC (I know in the video you specified 8Mhz for the 6300).

The photo had an NEC V30 in it, but the footage was shot using the stock 8MHz 8086 CPU in the 6300. And I verified it was 8MHz because the crystal on the motherboard is 24MHz.


I'm kinda curious about other clones and their performance now.

I wrote a benchmarking tool and there's a discussion about it over at http://www.vintage-computer.com/vcforum/showthread.php?28026 if you're curious. Lots of clones are compared; check the "Score=" line in the results that people have posted. One of these weekends I'll bang out a more friendly tool that gathers everything into a comparable database, but I haven't had the time recently.

Trixter
March 29th, 2012, 08:04 PM
A very nice professional-looking video, Jim! :thumbsup: Is that 3.5" drive in the front a homebrew job?

Yes, and there are some close-up photos in the video. I was careful to note in the video that the machine was not stock -- I didn't want people to think that 6300s came with a 3.5" bay.


Mine still has the two 5" floppies (I recently replaced them with Mitsubishis because the latter has a slightly better build quality than the original).

I love the original drives because they were quiet -- almost completely silent.


Of the early alternatives to the IBM 5150, I liked the NEC APC and the 6300 the most; when you got the 5150 fully fitted out, it ran you about as much as either the APC or the 6300. But no, I got a 5150 because it was more popular.

I'd never heard of the NEC APC -- looks like a really neat machine!


We were pretty flush back then and could have dropped a hundred K without blinking. Nothing--AT&T just didn't understand how to sell computers.

My father has some horror stories from that time. One time he visited a warehouse trying to resolve an issue and was astonished to see shelves 30 feet high, 300 feet long, 20 rows deep that were overflowing with unsold 3B1s (aka the 7300 or "Unix PC"). That was semi-confirmation of his doubt, that AT&T was really screwing up their strategy. Unfortunately, his fears were truly confirmed when he was let go in 1987 after 26 years with the company (his position at the time was manager of the printer line, and AT&T decided to drop the printer line, and him with it).

Trixter
March 29th, 2012, 08:13 PM
Can the graphics chipset do anything in addition to the CGA modes other than 640x400x1 or 8x16 text boxes?

Special features of the stock display board and AT&T color display were:


640x400x1
8x16 text font in both 80-col and 40-col (this was fixed -- there was no option to show the typical 8x8 CGA font)
Could degauss the color monitor in software (strobing a pin would fire the degauss). I would have demonstrated this, but my color monitor is unhealthy and the circuit is broken (it won't even degauss when powered on)
Both color and monochrome monitor can display underlined text in text mode, something usually limited to IBM MDA and Hercules
Because the 640x400x1 mode required 32K of video RAM, there was 32K RAM available to all modes. The diagnostics cycle through 8 80x25 text pages and 16 40x25 text pages. Because the page/bank was selectable via a port, you could also theoretically have 2 hardware pages of 320x200x4 CGA (but I don't recall if any games used this, and I haven't tried to program it myself yet)


If you spent extra money on the AT&T DEB (Display Enhancement Board), you kept the color monitor but gained the following:


640x200x16
640x400x16
Could overlay textmode on top of 16-color graphics mode and update both independently


I have never seen a DEB in action. I have an AT&T 6286 with an AT&T-brand Paradise VGA board that emulates AT&T video modes (verified 640x400x1) but I don't know if it also emulates the DEB special modes or text+graphics overlay mode.

Chuck(G)
March 29th, 2012, 09:03 PM
Unfortunately, his fears were truly confirmed when he was let go in 1987 after 26 years with the company (his position at the time was manager of the printer line, and AT&T decided to drop the printer line, and him with it).

I don't know if you're interested, but I've got the AT&T-branded daisywheel (I think also made by Olivetti) for the 6300. It's yours if you'd think it'd bring some pleasant memories back to your dad.

Trixter
March 29th, 2012, 09:16 PM
That's very kind of you, but it's not necessary. Before I made the video, I invited my dad and brother over to check out the restored machine, and even peruse their 25-yr-old files still intact on it -- while they were mildly amused, their reaction was definitely a few dB levels quieter than what I was expecting. I guess I was our 6300's biggest fan.

I'd never seen the daisywheel; the printer we had was the AT&T 9-pin dot matrix (I think it was the AT&T 572, and IIRC it was OEM'd from C. Itoh).

Ole Juul
March 29th, 2012, 11:14 PM
Be careful with that keyboard--open it up and see if you see a 5V regulator . . .
Thanks for the warning. It will take a while before I get to this project, but I just now took the time to open up the keyboard and there is indeed a 7805. Surprising number of chips in that, including a socketed UMWA098, a UM8035-6 and some TTL and stuff. :) I also took note of the model number on the back and it is KB5151AT&T, so it's probably all good. I do regret not having the original KBD but I guess a 1987 one isn't a bad compromise. Since this keyboard doesn't have the mouse port on it, I wonder what they did. Can a regular serial port work the same?

pearce_jj
March 30th, 2012, 12:06 AM
Daisy-wheels were fantastic... I remember my mother printing out reams of accounts on a Tandy DWP-something (210 maybe?) - the whole desk shook (a lot) as it literally thumped out the letters; then there was the noise... and of course, the top of the 'e' always broke off first :)

Chuck(G)
March 30th, 2012, 08:23 AM
Jim, I went and had a look--it's an AT&T 457, last serviced in 1988 by AT&T in San Leandro. Definitely an Olivetti product.

Not quite the block of lead that the Qume or Diablo printers were, but still very heavy.