EEVblog #1348 - World's First IBM Compatible PC - The Compaq Portable

A look at and teardown of the world's first IBM PC compatible PC, the Compaq Portable.
Also some meter and oscilloscope part 1 repair action...

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#Teardown #Compaq #Retro

[nnsda]

Would appreciate a part 2, enjoy seeing you solve these problems 😀

[TheDefpom]

@12:00 C42 on the front edge is blown up ! I spotted it immediately.

[vwestlife]

Compaq was by far *not* the first IBM PC clone -- but as they say, history is written by the winners. Columbia Data Products introduced their first IBM PC clone in June 1982, five months before Compaq, and just like Compaq they also used a legal "clean room" ROM rather than an illegal copy of IBM's ROM like some other companies did. But Columbia stopped making PC hardware in 1987, while Compaq lasted until 2001 when they were bought out by HP.

p.s. Bill Gates never said "640K ought to be enough for anyone", either -- especially since when he supposedly said it in 1981, the first version of the IBM PC's ROM was limited to a maximum of 544K of RAM, not 640K.

[FarrellMcGovern]

A joke from back in the day...

Q: How can you spot a Compaq user?
A: One arm is longer than the other!

[TroySleepwalker]

19:56 I see one of those socketed ram chips has let the magic smoke out at some point. 2nd one down from the top right.

[Screamingtut]

Dave, there was a blown Tam cap C42 on the floppy board just below the big brown Caps C23 & C24

[johnmoorhead]

I hired on as Service Manager in 1979 to Store #85 of Computerland, which was a chain of retail stores all over the U.S. - this one was in Sacramento CA. I worked for the local franchise which grew to 5 stores in northern California till 1987. I went to many service training seminars over the years including at IBM for the original PC. That one was held at one of their labs and was a week-long, deadly serious affair. When Compaq came on the scene I attended their equivalent multi-day training in Houston TX., and it was much more light-hearted - I think they were even then trying to point a finger in IBM's stuffed-shirt image. That was held at the top of one of their 3 corporate tower buildings which were later acquired by HP as part of the real estate in their acquisition; ironically years later as an HP employee I visited that site again. The Compaq was quite an elegant machine and as you have discovered, it was designed to be modular and easily serviced. If I recall, the power supply can be removed without having to remove anything else; the video display was removed by first removing the AC line/switch block and then using a long screwdriver through that opening to reach the screw that is on the side. A funny but true story; the way they taught us how to open the case was to place one of your hands flat on the top center of the case and press hard; this would cause it to bow out a bit at the rear end; then hit it hard with the other hand as a karate chop, all while shouting "Hi-Yee"! That would cause the top section to pop right off and then you could access the innards; same thing with the bottom panel. We actually had to practice this maneuver with the sound effects in unison in class till everyone successfully got their computer cases opened. Later on, when I was working in the store and had to open up a Compaq "luggable" as they were called, I often followed this practice as well, to the great entertainment of store staff. It got slightly more funny when I actually performed the procedure in front of a customer (having judged in advance whether that customer would mind too much). I still have one of these luggables; have not powered it on in 20 years and I'm sure it needs to be re-capped, but it's complete with the co-processor, an enhanced set of cards (AST multiiport serial/parallel) and a 20gb hard drive, which required its own separate controller. I last used it as a "portable serial protocol analyzer; using the serial port with specialized software to monitor the data stream and/or inject bytes as necessary to debug serial peripheral issues. As I recall, the video should display just fine on the build-in screen even with that Composite/CGA card installed; at power-up you should see the memory counting up and then a BIOS message first, then the boot prompt. Switching between the built-in monochrome versus external color was a function key combo. I've got all the manuals for it stashed somewhere in the garage including the service manuals.

[rdaw]

13:43 Wow! That thing has SOVIET parts in it! That EL74LS74 chip was made in the USSR!!!
EL was Soviet export marking of Western-compatible parts.
But they are still recognisable because of font and crappy (usually) brown plastic.

UPD: Oh, there is also EL7438 on the same board

[donaldashworth]

While working at Compaq (when only campus 1 and 2 existed) we had a version of this for the military with a "Loren" label. If I remember correctly the main difference was a -5 VDC at the serial port for reference. I have no idea why.

[oldestnerd]

Wow, I have several of those antiques in your introduction. IBM tech manuals were amazing. Even sharing source code for a lot of the BIOS.

[CathyInBlue]

I remember when I was planning my purchase of my first PC, I was agonizing over whether to get a 286 or wait until I could afford a 386. A teacher told me that there was no reason why I would ever need the computational power of a 386.

[stanburton]

Used to work for Walt Russell, employee #7 at Compaq, he designed much of the case and peripherals for that machine. He left Compaq when it became essentially TI all over again...

[mattelder]

Compaq Portables always reminded me of sewing machines in the cases that were often used for them.

[artursmihelsons]

Like Your enthusiasm, Dave, for saving piece of history! :) Waiting for part two..

[Wobblybob]

11:35 Waxes lyrical about replacing tantalum caps. Next shot, point directly at blown tant. Then spends the next 10 minutes tearing computer apart looking for it. Classic Dave

[ufohunter]

I became an IBM and Compaq certified technician in 1984.
Brings back lots of memories, not all rosy.

[JohnVance]

I’m pretty sure this is the system that the first season of Halt and Catch Fire was based on.

[bootyholeman]

This was my first PC. The hard drive was on a ISA expansion card. Yes is was a long expansion card with a HDD screwed to it. the front section of the card had the controller. I believe it was called "Plus Hardcard 20" for 20mb's. I received it in the early 90's, it was in a large shed owned by my friends parents, they used it at their business but was since retired. They gave it to me for helping clean out the shed. I do recall luging that thing to my friends house that was several blocks away. It was heavy, and I had to stop after every block for a rest. Luckily it was so sturdy I could use it to sit on while I rested. haha

[flomojou]

Really looking forward to the repair!!

[pmjd]

I remember using a genuine IBM portable back then, 1989-ish, too. I don't recall it being very portable at all. I set it up to monitor activity on a "telecomutting" system I ran when I worked for IBM.