Articles in the "Hardware" Category

The VS-100 Voice Synthesizer

The Alpha Products VS-100 was a popular voice synthesizer for the TRS-80, selling thousand of units. Introduced in 1983 by Alpha Products for a price of $69.95, the VS-100 was available for the TRS-80 Model I, Model III, Model 4, and also the Color Computer. Alpha Products lowered the price of the VS-100 several times; it was reduced to $49.95 in 1985 and $24.95 in 1987.

The VS-100 was a 3″ by 5″ unit that connected to the expansion port of the Model I, Model III, or Model 4. It came with a power adapter, but not the required external speaker. Alpha Products sold a “handsome speaker module” separately for $5.95.

The Holmes Expansion Mainframe

The Holmes Expansion Mainframe was a popular alternative to the Radio Shack Expansion Interface for the TRS-80 Model I. Introduced in mid-1982, the Expansion Mainframe offered expansion options in a different manner than its competition. It provided extra features through the installation of special plug-in modules, also sold by Holmes Engineering. In addition to supporting the Model I, the Expansion Mainframe was also described as being compatible with the PMC-80 when used with the PMC to TRS-80 adapter sold by Personal Micro Computers.

The Expansion Mainframe was known as a very reliable unit, with gold-plated connectors and all data lines fully buffered. For maximum reliability, Holmes Engineering also recommended gold-plating the connector on the Model I itself using a product such as Gold Plug 80. The Expansion Mainframe was often paired with two earlier Holmes Engineering products, the SPRINTER speed-up board and the Internal Memory memory expansion.

The Expansion Mainframe was housed in an off-white metal enclosure, measuring 16 1/2″ by 9 1/8″ by 2 7/8″, which also served as a base for the Model I monitor. It came in two versions:

The Radio Shack Double-Density Disk Kit

The original TRS-80 Model I, when paired with a Radio Shack Expansion Interface, was only capable of single-density floppy disk access. This limitation was addressed by the Percom Doubler, introduced in 1980, which modified the Expansion Interface to add double-density. The Percom Doubler soon became the de-facto standard for double-density interfaces on the Model I. Almost all companies that created double-density add-ons made them compatible with the Percom Doubler.

The Radio Shack Double-Density Disk Kit (catalog number 26-1143) was Radio Shack’s own double-density add-on for the Model I. Introduced on May 1, 1982 (nearly one and a half years after the Model I was discontinued), the Double-Density Disk Kit cost $149.95, not including installation. Despite the official name, many people referred to it as the Radio Shack Doubler.

Like the Percom Doubler, the Double-Density Disk Kit installed inside the Radio Shack Expansion Interface. It was described this way in the catalog:

The Stickeroo Joystick Interface

The Stickeroo Joystick Interface was an Atari-style joystick interface for the TRS-80 Model I and System 80 computers. Introduced in 1982, the Stickeroo was sold by Micro-80, an Australian magazine dedicated to the TRS-80 and System 80. (The System 80 was nearly identical to the computer sold in the United States as the PMC-80.) The original advertisements also mentioned an upcoming TRS-80 Model III version of the Stickeroo, but that was presumably never produced.

The “Micro-80 Product Catalogue” was a multiple page section of Micro-80 that sold TRS-80 and System 80 hardware and software by mail-order to “customers throughout the Australian and Pacific region.” Many of the products were imported from the United States, but others, including the Stickeroo Joystick Interface, were products of Australia.

The CR-510 Card Reader

The Radio Shack CR-510 Card Reader was introduced in 1984 at a cost of $1595.00. Aimed primarily at schools, it appeared in the Radio Shack catalog under the headline “Automate Time-Consuming Tasks with a TRS-80 Computer Card Reader.”

Administrators, teachers, and students can benefit from this new TRS-80 input device. Automate data compilation, evaluate surveys and polls, or correct multiple choice tests. The CR-510 provides single, demand, or continuous feed operation and is controlled through manual switches or software. Cards must be at least 6 inches in length and can be either marked or punched (with standard keypunch).

The CR-510 communicated through the RS-232 port, so it could connect to any TRS-80 computer. It came with 200 cards and a disk with sample drivers written in BASIC and COBOL. Those sample drivers must have been important when you consider that there was no software available for the CR-510!

The Radio Shack Lower Case Kit

The inability to display lower case characters was a well known deficiency of the TRS-80 Model I. There were a number of third-party modifications created to address that limitation, the most popular of which was the Electric Pencil lowercase modification. But the Radio Shack Lower Case Kit (catalog number 26-1104) was Radio Shack’s official solution for adding lower case to the Model I.

Introduced in late 1979 at around the same time as the Scripsit word processor, the price for the Radio Shack Lower Case Kit started out at $99.99 but was soon lowered to $59.95. Despite the use of the name “kit,” Radio Shack required installation by a Radio Shack technician.

The Electric Pencil Lower Case Modification

The best known limitation of the TRS-80 Model I was its inability to display lower case characters. Although the lower case characters were present in the character set, the Model I lacked the extra memory chip needed to store the bit corresponding to lower case.

The significance of this limitation has been exaggerated over time (it’s worth noting that the contemporary Apple II also lacked lower case), but it created a real problem for word processors. There were many lower case upgrades for the Model I designed to fix the omission, ranging from simple to more complex.

One of the simplest modifications was commonly referred to as the Electric Pencil lower case modification. It was first detailed in 1978 in the manual for the TRS-80 version of the Electric Pencil word processer, for which it was designed. It quickly became the de facto standard for lower case upgrades and was widely reprinted elsewhere. Several companies, including Microtronix, sold the parts and instructions for the modification as a kit.

The Percom PHD

The Percom PHD was a line of 5 1/4" Winchester hard drives sold by Percom Data for the TRS-80 Model III, as well as several other computers. Introduced by Percom in 1982, the PHD used what was described as a “smart microprocessor-based drive controller” to allow up to four PHD drives to be connected to the Model III at one time. The Model III version also worked with the Model 4, but Percom never sold a version for the Model I.

The PHD drives were available in 5, 10, 15, and 30 megabyte sizes. The model numbers corresponded to the drive capacity: the PHD-10 was a ten megabyte drive. The prices started at $2,495.00 and increased with drive size.

The BETA-80

The BETA-80 was an “intelligent” cassette tape system that could store up to one megabyte on a single digital tape cassette. It was sold by MECA as an alternative to an Expansion Interface and disk drives. MECA sold versions of their digital tape systems for a number of computers using different names:

  • BETA-80 for the TRS-80 Model I (and later the Model III)
  • TAPE-II for the Apple II
  • BETA-EX for the Exidy Sorcerer
  • ALPHA-1 for S-100 computers

The Amdek Amdisk-III

The Amdisk-III was an external dual-3″ (not 3 1/2″) floppy disk system introduced by Amdek Corporation in 1982. The TRS-80 Model III version was originally priced at $899, but that price was soon reduced to $599.00 and later $499.00. Versions were also available for the TRS-80 Color Computer, the IBM PC, and the Atari 400/800. 80 Micro tested a prototype version for the Model I, but it is unclear if that Model I version was ever sold. Amdisk also sold a single-drive system, the Amdisk-I, that was only available for the Apple II.

In 1982 to 1983, there were four “microfloppy” formats competing to replace the 5 1/4" floppy: