Hardware

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

By · January 31, 2008, 12:25 AM PST · markwkaelin

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  • 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.

  • 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.

  • A few screws

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

  • 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.

  • Haunting

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

  • Thunderdome

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

  • 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.

  • 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?

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • Single board layout

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

  • 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.

  • 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.

  • Don't touch

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

  • Uncaged

    The transformer is just your basic one -- nothing special.

  • Solder

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

  • 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?

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.
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By Mark Kaelin

Mark W. Kaelin has been writing and editing stories about the IT 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, and TechRepublic.

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