Articles in the "Hardware" Category

The TRS-80 Telephone Interface

The TRS-80 Telephone Interface was the first modem that Radio Shack sold for the TRS-80 Model I. According to the product introduction in the November 1978 issue of the TRS-80 Microcomputer News:

Data communications can materially expand your computing horizons. It means you can communicate with large “data base” computers, using your TRS-80 as an intelligent peripheral.

There were two versions of the Telephone Interface: the $149.00 Telephone Interface I (catalog number 26-1170) which was introduced in 1978 and the $199.00 Telephone Interface II (catalog number 26-1171) which replaced it in 1979.

The TRS-80 System Carrying Case Set

The TRS-80 System Carrying Case Set (catalog number 26-500), also known as the Model I Carrying Case Set, was Radio Shack’s solution for transporting a TRS-80 Model I. It was introduced in late 1978 for a price of $69.95. Radio Shack increased the price to $75.00 on July 1, 1980 except for a brief sale price of $39.95 that ended December 31, 1980.

Although the Model I wasn’t a portable computer (by any stretch of the imagination), people often needed to move a Model I to a new location. For example, many people kept their Model I at work during the week and brought it back home for the weekend.

The TRS-80 System Carrying Case Set was two cases designed to hand transport a Model I keyboard unit, video display, and associated parts.

The JFF Electronics Color Graphics Interface

The Color Graphics Interface from JFF Electronics was one of the first color add-ons for the TRS-80 Model I. It cost $49.95 when it was introduced in early 1979 by JFF Electronics Ltd of Saskatoon, Canada. The Color Graphics Interface didn’t require a Radio Shack Expansion Interface but plugged directly into the Model I 40-pin expansion bus. It didn’t include an enclosure but was a bare circuit board. However, it did include a regulated power supply on the board.

The Color Graphics Interface could be connected to either a color monitor or a color television set. It supported several different modes:

  • a text display with two colors and reverse video
  • a 64 by 192 mode with eight colors
  • a 128 by 192 mode with four colors (in two sets)
  • a 256 by 192 mode with two colors

The XRX Cassette Modification

The XRX was an official hardware modification from Radio Shack for the TRS-80 Model I. It installed inside the Model I and made it easier to load programs from cassette using Level II BASIC. Radio Shack dealers would install the XRX for free on any unmodified Model I. (For owners with a modified Model I, the installation price could range from $30.00 to $50.00.) Model I’s built after the XRX was introduced included it as a standard feature.

The original version of the modification, usually called the XRX or XRX-1, was introduced in early 1979. At the time, Radio Shack only called it “the modification.” Because it wasn’t a named product with a catalog number, it was known by many names by users, including XRX, XRX-I, XRX-II, XRX-III, XRX2, XRX3, XRS-2, and X2X. These were all different names for the same modification.

The Photopoint Light Pen

The Photopoint was a popular light pen for the TRS-80 Model I and Model III. It cost $19.95 and was sold by Micro Matrix of Pacifica, California. Although virtually unknown today, light pens were once considered the way of the future to select items on a computer screen. The Photopoint was much less expensive than competing products when it was introduced around 1980 (some of which cost hundreds of dollars) and provided a way to experiment with light pen technology.

Light pens at the time worked using two approaches. The first was to detect the screen refresh. All CRT displays refresh the screen by continually scanning a beam from left to right and top to bottom.

Orchestra-90

Orchestra-90, also known as Orch-90, was a popular hardware sound add-on for the TRS-80 Model III and Model 4, and later the Color Computer. It was created and sold by Software Affair of Sunnyvale (originally Santa Clara), California, along with Orchestra-85, the equivalent add-on for the TRS-80 Model I. It became more popular when Radio Shack began selling a licensed version of Orchestra-90 in 1984. At its peak of popularity, there were over a thousand song files available from CompuServe, Delphi, and BBS’s around the world.

Both Orchestra-90 and Orchestra-85 were enhanced versions of Software Affair’s earlier Orchestra-80. Orchestra-85 (the Model I version) was introduced in 1981 for $129.95. Orchestra-90 (the Model III version) followed a few months later for $149.95. Users who wanted to upgrade the Orchestra-80 could send their unit to Software Affair and pay $69.95 (plus $2.00 for shipping and handling) to exchange it for an Orchestra-85.

Silver-It

Probably the biggest design mistake Radio Shack made with the TRS-80 Model I was their decision to use solder-coated tin contacts (instead of silver or gold) on the Model I and Expansion Interface connectors. These solder-coated contacts tended to oxidize over time, leading to reliability problems and unexpected reboots. The usual solution was periodically to use a pink rubber eraser to remove the oxidation. This was supposed to be done every month, but many people did it every week, or even every day.

There were also several hardware solutions to the problem. The best known was the Gold Plug 80 from E.A.P. Company. Gold Plug 80 worked by installing gold-plated contacts over the originals. This completely eliminated the reliability problems. The only downside was that the double set of contacts did extend slightly from the case.

A lesser known way of stopping the reboots was Silver-It, sold by Roger Fuller through Fuller Software of Grand Prairie, Texas. Silver-It worked by recoating the oxidizing contacts with silver.

The Exatron MM+

The Exatron MM+, also known as the Exatron Memory Plus Expansion, was an alternative to the Radio Shack Expansion Interface for the TRS-80 Model I. It was designed and sold by Exatron of Sunnyvale, California for use with their floppy disk storage alternative, the Exatron Stringy Floppy. Despite the fact that it was barely advertised and seems to have been only sold briefly in 1981, the Exatron MM+ remains one of the best remembered Expansion Interface alternatives.

The Exatron MM+ was aimed at users of alternative Model I storage options, such as the Exatron Stringy Floppy, the Meca BETA-80, or the JPC Products TC-8. Unlike the Radio Shack Expansion Interface, the Exatron MM+ didn’t include a floppy disk controller. But it did add additional memory, a parallel port, and a serial port. Unlike the Microtek MT-32, another lightweight Expansion Interface alternative, the Exatron MM+ also extended the Model I expansion bus. This meant that peripherals that connected to the bus, such as the Stringy Floppy or the BETA-80, could still be attached to the MM+.

The Model I Printer Interface Cable

One of the limitations of the cassette-based TRS-80 Model I was that it had no printer port. There were many cassette programs designed to use a printer, such as Electric Pencil and Scripsit, but no simple way to add one. Only a few Radio Shack printers were designed to connect to a cassette-based Model I directly.

The usual approach to adding a printer was to buy a Radio Shack Expansion Interface. In addition to providing extra memory and a floppy disk controller, the Expansion Interface also added a printer port. But a fully equipped Expansion Interface cost more than a Model I itself, and a unit with no memory still cost $299.00. Another option was a lighter-weight third-party Expansion Interface, such as the Microtek MT-32 or Exatron MM+. But this was still overkill if all you wanted was a printer.

The Microtek MT-32

By itself, the TRS-80 Model I was capable of only limited expansion. In order to add memory beyond 16K and support floppy disk drives, Radio Shack sold an external device they called an Expansion Interface.

The Expansion Interface could expand memory to 48K, add a parallel printer port, and add a disk controller for connecting floppy disk drives. But an Expansion Interface with 32K of memory cost $597.00, almost $100 more than a 4K Model I. What if a Model I owner didn’t want (or couldn’t afford) disk drives but still wanted to add memory and a printer port?

The MT-32 from Microtek, Inc. of San Diego, California used a different approach from the Radio Shack Expansion Interface. The MT-32, introduced in mid-1980, offered only two features: the ability to add 32K of RAM (for a total of 48K) and a parallel printer port.