The Muscle Micros

written by Matthew Reed

Portion of the amusing comic drawn by Eric Grevstad that accompanied the article

The April 1983 issue of 80 Micro contained an article called “The Muscle Micros.” Written by the “80 Micro Tech Staff”, the article profiled “three sleek supercharged” TRS-80 Model III computers equipped with hard drives (commonly known at the time as Winchester drives). The three computers profiled were:

• The BT Hard Disk Model III Microcomputer from BT Enterprises of Bohemia, New York
• The MTI Mod III Plus from Microcomputer Technology Inc. (better known as MTI) of Santa Ana, California
• The Computex Model 326 from Computex of Houston, Texas

Much like the earlier Adcock & Johnson Model 3000, which was a Model III repackaged in a transportable case, these companies bought Model III computers from Radio Shack and then extensively upgraded them into their own branded products. The article described what made up these “muscle micros”:

What is a “muscle micro?” It’s a Model III with hard-disk storage built into the standard cabinet. They contain very little standard Radio Shack hardware. Essentially, the people making the MMs buy stock 16K Model IIIs and add memory ICs, floppy- and hard-disk controller circuitry, new monitors, keyboards¹, disk drives, power supplies, fans, speedup kits, and, in MTI’s case, a new paint job for the cabinet.

All of these computers cost between four and five thousand dollars, depending on the desired configuration. Each of the companies upgraded the memory to a full 48K and offered an upgrade of the processor speed from 2MHz to 4MHz. BT and Computex used the Holmes Sprinter² speed-up kit, while MTI used their own speed-up. BT and Computex replaced the stock CRT with a Langley-St. Clair replacement. MTI used an “RCA equivalent slow-decay green-screen monitor.” All three had built-in fans and heftier power supplies. They also added 40-track or 80-track floppy drives.

But the real highlight of the upgrades was the hard disk storage. Each computer came with hard drives with sizes ranging from 5MB to 15MB. (These sizes are in megabytes, not gigabytes or terabytes. There are a thousand megabytes in a gigabyte and a thousand gigabytes in a terabyte.) All three of the systems ran DOSPLUS 4.0 for their operating system. DOSPLUS 4.0 was probably the TRS-80 operating system with the best hard drive support at the time.

For example, the computers from BT Enterprises came in three configurations:

• the 4 x 5, with a 5MB hard drive, cost $3,995.00
• the 4 x 10, with a 10MB hard drive, cost $4,195.00
• the 4 x 15, with a 15MB hard drive, cost $4,295.00

Adjusted for inflation, these would range from eleven to twelve thousand dollars in modern money. The BT Enterprises advertisements told readers to stop in at any of their twelve dealers for a demonstration.

The built-in hard drive and other upgrades would have made a Model III competitive with Radio Shack’s own business computers, such as the Model II. The upgrade computers also would have had the advantage of being able to run ordinary Model III software. On the other hand, they would have had the disadvantage of being unable to run Model II business software.

These “muscle micros” must have been impacted by Radio Shack’s introduction of the TRS-80 Model 4 on April 26, 1983. The Model 4 already featured many of these improvements, such as 4MHz speed and expanded memory, and was available directly from Radio Shack. Although no version of the Model 4 ever had a built-in hard drive, Radio Shack did offer external hard drives and later versions even had a very nice green screen CRT.

It’s amusing and somewhat sobering to realize that a $35.00 Raspberry Pi 3 has specifications which dwarf even the most powerful of the “muscle micros.”

Related Posts:

The TRS-80 Telephone Interface

The TRS-80 System Carrying Case Set

The JFF Electronics Color Graphics Interface

The XRX Cassette Modification