TRS-80 Microcomputer System Model III
The Model III is basically an upgrade of the Model I, which was released three years earlier. It has the same CPU, but it is faster, has more memory, and the floppy drives hold twice as much data, although the Model I could be upgraded to some of these features.
The major reason for developing the Model III was because the FCC had just instituted new regulations about RF emissions generated by computers and other electronic devices. The Model I was completely unshielded and was unable to pass the emission restrictions.
The Model III system is entirely self-contained. The original Model I had edge-type connectors with ribbon cable connecting the keyboard to the (optional) Expansion Interface, as well as the floppy drives. This type of connection is very unreliable, and led to the occasional system crash or lock-up.
Introduced July 1980
The improvements of the Model III included built-in lower case, a better keyboard, and a faster (2.03 MHz) Z-80 processor.
Manufacturer: Radio Shack
Date: July 1980
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