Historic Microcomputer Restoration?

Pojodojo asks: "I am doing an independent study next semester with my computer science professor which we decided to call Historic Microcomputer Repair and Restoration. I will be working with such classics as the Altair 8080 and the Apple II. After I have repaired and or restored these machines, I will put them in a display for others to see. I have the opportunity for a modest budget to get equipment to put in the display, and would like to know is, what sort of things would you as fellow comp sci geeks like to see in a Historic Computer exhibit?"

Comments

Duh

[baldass_newbie]

Ascii pr0n, obviously.
*sheesh*

The abacus

[luder]

After all, it was one of the first calculating devices.

well...

[joe 155]

.. I don't know the extent to which it fits your definition, but if I was to think of a bitchin' computer (insomuch as it could do some level of computing). It would be an Amiga 500, god I loved that... if you want something a little more in the line of "computer" I would say collosus, the original bletchly park beast... it could still out perform a P4....

Re:well...

[moosesocks]

You've got to love it that when a computer is so efficent that it's only limited by the speed at which data can be fed into it.

When testing to see how fast the Colossus could perform reliably, engineers found that it would perform flawlessly until it was running so fast that the paper tapes that fed the input data into Colossus caught fire, at which point they abandoned the experiment for fear that they'd burn the wood-framed building down. A true testament to Turing and the other fine scientists at Bletchly Park.

Pity Churchill ordered it destroyed after the war was over. It was decades ahead of its time.

The Amiga 500

[scenestar]

this thing is mroe important seeing as it was used for years for video editing.

But who am I to judge.....

Variety of platforms

[Marxist Hacker 42]

There was an amazing variety of 8-bit platforms manufactured between 1976-1985, the more you have the better. But take my advice, having refurbished a number of these machines: Plan on buying 3 for every one you get working, Ebay is your friend, no single machine is worth more than $5. You should be able to pick up core cpu/keyboards for $15 following these rules. Use a modern audio cable switch box and a single composite monitor to switch between them- Composite monitors are hard to find and expensive, but many modern cheap 15" TV sets have the correct RCA inputs.

I think your best bet...

[Bin_jammin]

is to stick with well documented hardware. The two you've picked so far ought to more than fit the bill, but considering you've added "repair" to the title of the class, I assume you'll be doing pcb level hardware repair. This is a LOT of fun and frustration at the same time, but if you start digging into machines that nobody's thought of, cared about, or kept track of over the past 30+ years you probably will start getting into headaches of trying to diagnose some seriously weird bugs. Not to discourage you from this course of action, in fact far from it, it sounds like something I would have enjoyed in my public schooling days (or at least getting credit for it). Find clubs that support the machines and can give you advice, don't try to go it alone, after all, the machines were built by teams, teams should help you rebuild them. Most of all remember to have fun!

Computer History Museum

[Tackhead]

If you haven't already done so, you and your professor need to contact the Computer History Museum in San Jose.

Next week's big festivities involve a restored PDP-1.

Their collection of hardware is pretty much unmatched, and is open to the public. What's on display is the tip of their collection's iceberg. Who knows what might be kicking around in the background, just waiting for a small team of geeks to restore?

And conversely, who knows what might be kicking around in your classmates' basements that's on CHM's wish list?

so many milestones...

[TheSHAD0W]

Here's some computers I'd recommend you try to get. Each represents one or more milestones to what we now consider commonplace. (I've left out some of the more obvious ones; please forgive me if I've named some you consider obvious.)

Desktops:
Commodore PET 2001 (color chicklet keyboard).
Sinclair ZX-80/81.
Coleco Adam.
DEC Rainbow 100.
Amiga 2000.

Portables:
TRS-80 Model 100/102.
Osborne 1.
Compaq suitcase PC.
HP 200LX.
Apple Newton.
Toshiba T1000.

How about...

[EnigmaticSource]

A DEC PDP-11/73, my personal favorite.

Probably the easiest computer to rebuild from the classic era as there is only one bus (Unibus), and nothing but traces and some very simple electronics on the backplane. Well that and you could hit them with a hammer.

The PDP-11 series, along with the PDP-8's were some of the first nodes on the ARPANET and you can still get working Ethernet adapters for them.

Hell, I still miss mine (Viper tape drive, RSX/11, RSTS/E 10, BASIC Plus2, 512MB EDSI drive).

(You can still find these things running if you look hard enough... (Try asking old medical/dental offices, most of them ran PDP/11's))

The LINC speed control...

[dpbsmith]

I'm not sure whether this can be easily retrofitted into other computer designs, but one of the coolest things on the LINC--sometimes billed as "the first personal computer"--was the adjustable speed.

The LINC had a pair of dials on it: one was a (continuous) potentiometer, like a volume control, the other was a four-position "decade" switch. The pair of dials joint produced a signal that could be used to make any of a number of front-panel functions auto-repeat at a variable rate. In particular, you could make the "single-step" function auto-repeat. The pot adjusted the repeat rate continously over about a ten-to-one range. Each switch position was a factor of ten faster than the last. The slowest speed was about two per second.

This means that you could make the LINC single-step through its programs at an rate from about 2 to 200,000 steps per second... the later being about half of its full speed.

So, you could take a program... run it at 2 steps per second and watch the lights flash... then gradually speed it up over a five decades to 200,000 steps per second. At 2 steps per second if you watched closely from time to time you'd see one dot on the screen flash momentarily. As you sped it up the, the flashes would occur more rapidly... then you could see it was forming characters... then lines of text appearing at about the speed of a dot matrix printer... then finally a whole screen of flicker-free text.

Meanwhile, the LINC's speaker, attached to bit 6 of the accumulator, would gradually change from ticks to a buzzes to beeps.

I never saw anything that gave you such a feeling for just how incredibly goddam fast a computer was. Even one running at about 0.5 megahertz clock rate.

You actually could build a LINC from scratch, I suppose, since it was discrete components and the design was public domain. But it would be equally interesting to take a "stock" computer of almost any vintage and give it a continuously variable clock, a la the LINC.