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Hardware

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

By Mark W. Kaelin January 30, 2008, 11:11 PM PST

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Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Simple times

Simple times

The Radio Shack TRS-80 Color Computer was one of the first personal computers to have wide acceptance. In this TechRepublic Cracking Open Gallery we take a look at what is inside this personal computer dinosaur.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Warranty

Warranty

The TRS-80 existed in a time where manufacturers did not want consumers messing around inside their insides. Much like Apple still insists today.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

A few screws

A few screws

After removing the sticker, you merely have to loosen six screws to get to the electronics inside.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Yuck!

Yuck!

This TRS-80 has been out of commission so long the dust has actually fused with the chips inside the case. Motorola seems to be the chip maker of choice.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Haunting

Haunting

The vision of metal oxidation supplemented by dust and dirt is going to haunt my memories forever.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Thunderdome

Thunderdome

For some reason the power transformer is housed in a steel cage.

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click.png
Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Click

Click

The keyboard is standard QWERTY, but it also has that IBM Selectrix-like click-click action. I really miss that in many modern keyboards.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

An old ribbon connector

An old ribbon connector

Who knew the ribbon connecting cable was around back then? I wonder how long ribbon technology has been employed?

Anyway, this ribbon, unlike more modern connections, is soldered. Of course, I’m not supposed to open the case, so why should this connection ever need to be severed?

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Some relief

Some relief

The chips under the keyboard are much less disgusting to look at. You’d be hard-pressed to find a chip in a TRS-80 NOT made by Motorola.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Chip research

Chip research

I know how you love to know what each chip does so I did some Google research.

The two big chips at the bottom of the image are peripheral logic chips.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

More about chips

More about chips

The next big chip is a trigger inverter (yeah, I don’t know exactly what that means either). I’m not sure what the small chip beneath it does, but I can tell you all of these chips are available to buy.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Chip farm

Chip farm

This TRS-80, according to what I could find on the Internet shipped with 16K of RAM. These 8 chips make up that RAM.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Decoder/Demultiplexer

Decoder/Demultiplexer

Here is a closer look at the bank of memory chips. The two smaller chips at the bottom of the image are for controlling the I/O of the RAM. They are called 1-of-8 Decoder/Demultiplexer.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Single board layout

Single board layout

It was obviously a much simpler time in the early 1980s when it came to personal computer mother boards.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Break it up

Break it up

There is one key that is different on the TRS-80 keyboard. The Break key was used to stop a Basic program from running. Ah, the days of the infinite GoTo Loop.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Ignore the crud

Ignore the crud

If you look past the grime on the chips you will see the brains of the TRS-80 in the 6809 CPU. That Tandy chip below it is the ROM chip holding Color Basic 1.2.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Don't touch

Don't touch

The power transformer is located in a cage inside the case.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Uncaged

Uncaged

The transformer is just your basic one — nothing special.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

Solder

Solder

Notice the soldered connections. Also notice the yellowish tint. Kind of disgusting, no wonder this TRS-80 CoCo was DOA.

Cracking open the Radio Shack TRS-80 Color Computer (CoCo)

TRS-80 CoCo

TRS-80 CoCo

While the TRS-80 was sophisticated for its day, by current standards it definitely has that feel of a simpler time. The Radio Shack TRS-80 Color Computer is a piece of personal computer history and it makes for a fascinating TechRepublic Cracking Open Gallery.

What other ancient piece of personal computer history would you like to see cracked open?

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By Mark W. Kaelin
Mark W. Kaelin has been writing and editing stories about the information technology industry, gadgets, finance, accounting, and tech-life for more than 25 years. Most recently, he has been a regular contributor to BreakingModern.com, aNewDomain.net,
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