TC-8 Cassette System

written by Matthew Reed

JPC Products advertisement for the TC-8

JPC Products advertisement from the
March 1981 issue of 80 Microcomputing

The TC-8 Cassette System was a hardware add-on from JPC Products that provided faster and more reliable cassette storage for the TRS‑80 Model I. Advertised as “The Poor Man’s Floppy”, the TC-8 provided features similar in many ways to the Exatron Stringy Floppy. The TC-8 could store up to 300K on an single 30 minute cassette tape. It increased the standard TRS‑80 cassette data rate from 500 baud to nearly 3000 baud. It also promised much greater reliability, “less than one bad load in a million bytes.”

The TC-8 was derived from the TC-3, a similar cassette system that JPC Products created in 1978 for computers based on the Motorola 6800 processor. When introduced in 1980, the TC-8 cost $69.95 for a kit and a $99.95 for a fully assembled version. Those prices soon increased to $89.95 for the kit and $119.95 for the fully assembled version. The JPC Products advertisements recommended that buyers consider the kit version, saying:

It is very easy to build. It should only take you an hour or so. Even if you have never built a kit before, you can build the TC-8.

If you can get toothpaste on a toothbrush, you can learn to solder. Our instruction manual will show you how.

JPC backed up that recommendation with their “Can’t Fail” guarantee, saying:

If you build the TC-8 and for any reason it doesn’t work, we will make it work at NO COST. All you have to pay is the shipping. We guarantee it!

Usage

The TC-8 plugged directly into the Model I expansion bus and a cassette recorder plugged into the TC-8. Unlike the Exatron Stringy Floppy (which had its utility routines located in ROM), the TC-8 software wasn’t always present and needed to be reloaded from cassette each time the Model I was started.

This required using the SYSTEM command to load the software from a cassette recorder plugged into the Model I. After the software successfully loaded, the cassette recorder could be disconnected from the Model I and plugged into the TC-8. Alternatively, two cassette recorders could be used, with one permanently plugged into the Model I reserved for loading the TC-8 software upon startup.

The TC-8 software used 550 bytes of memory (including a debounce utility) and added over 20 commands to BASIC. These commands resembled Disk BASIC commands and allowed using filenames up to eight characters long. For example, LOAD "FILENAME" would load a BASIC program using the TC-8 and SAVE "FILENAME" would save a BASIC program. Machine language programs could be loaded with the GET command and saved with the PUT command. There were also commands to save and load data within BASIC programs.

The TC-8 was for the Model I only; JPC Products never created a version for the Model III. In late 1982, JPC Products replaced the Model I version of the TC-8 in their advertisements with a new model for the TRS‑80 Color Computer. The new version, known as the TC-8C, provided the same speed and reliability, but extended the software to include the JBUG monitor. JBUG was a machine language monitor that offered assembly and disassembly features.

Categories: Hardware

Leave a Comment

All comments are moderated. The name and email fields are required, but your email address will not be published.

Thank you for commenting!