Monday, January 22, 2007

TRS-80 Model I (CLOAD)

Last week, as I was riding into work with a coworker, we were reminiscing about our first experiences with computers. Coincidentally, we both got our start on Radio Shack's TRS-80 Model I in the late 1970's. Back then, there were only a couple notable players in the personal computer world, Apple with it's Apple II, Radio Shack with their Model I and II, and the Commodore PET.

If you've ever worked with the TRS-80 Model I you'll remember commands like CLOAD and SYSTEM to read programs from the tape drive. In its most common configuration, there was no file system or operating system and BASIC was built into ROM (courtesy of Bill Gates). One of Microsoft's first big sales was licensing its BASIC interpreter, for around $50K, to John Roach, the chairman of Tandy, to ship with the TRS-80.

It was pure ecstasy the first time my coworker and I used a BASIC complier on the TRS-80 as our programs executed at seemingly blindingly fast speeds (less than 2 MHz clock cycle). The TRS-80 used Zilog's Z-80 microprocessor - if you've ever programmed it in assembly language, you'll remember that it didn't have multiplication or division in its instruction set so you had to iterate yourself to do that kind of math.

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