Articles in the "Hardware" Category
The Selectra-Print (originally known as the Selec-Term) was a device that connected a TRS-80 Model I to an IBM Selectric electric typewriter. It was sold by Micro Computer Devices Inc. of Anaheim, California. The TRS-80 version of the Selectra-Print cost $1,925.00 and included a modified Selectric II as part of the package.
The Selectric was an electric typewriter that used a “typeball” (which was removable and changeable) instead of individual typebars. IBM introduced the original Selectric (later known as the Selectric I) in 1961 and an improved version, the Selectric II, in 1971. The Selectric produced excellent output and eventually gained 75% of the United States electric typewriter market.
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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”:
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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+.
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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.
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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.
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The Aerocomp DDC was a popular double-density add-on for the TRS-80 Model I. It was introduced in 1981 by Aerocomp Inc. of Dallas, Texas, a company founded by John Lancione. Aerocomp was one of the longest lasting TRS-80 companies and the Aerocomp DDC was sold for almost a decade.
When it was introduced, the Aerocomp DDC cost $149.95. This was $20 cheaper than its primary competitor, the Percom Doubler II. Aerocomp also sold the Aerocomp DDC bundled with a choice of operating systems: DOSPLUS 3.3 for $189.95 and with LDOS for $239.95.
The Percom Doubler was the original Model I doubler and the Aerocomp DDC was designed to be software compatible with it. The Aerocomp DDC (like the Percom Doubler) used double-density encoding to increase disk capacity on a 40-track single-sided disk from 100K to 180K
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The Freedom Option was a CP/M add-on for the TRS-80 Model I, Model III, and compatibles. It was introduced in early 1980 by Field Engineering Consultants (better known as FEC) of Woburn, Massachusetts.
Originally, FEC sold two Freedom boards, both for a 48K Model I with disk drives:
- The Freedom Option allowed CP/M (or the included T8/OS) to run by disabling the Model I ROM. It cost $245.00.
- The Memory Expansion Option had the same features as the Freedom Option, but also added an extra 16K of RAM. This provided a full 64K of RAM for the Model I, meaning that 57K was available for programs when running T8/OS. It cost $295.00.
Both the Freedom Option and the Memory Expansion Options were fairly small boards that installed inside the Model I case. As one advertisement stated they were “easy to install plug-in boards; no wires or traces to cut; no soldering.”
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The Interstellar Drive, also known as Pion’s Interstellar Drive, was a solid state disk drive emulator that was sold by Pion, Inc. of Arlington (later Watertown), Massachusetts. It was introduced in 1982 for a base price of $1,095.00 for the 256K version.
The Interstellar Drive was an external 9" by 8 1/2" by 4" unit with its own power supply. It was compatible with the TRS-80 Model III and Model 4 and included drivers for the TRSDOS and LDOS disk operating systems. By using different host interfaces, the Interstellar Drive was compatible with a number of computers, including the Apple II and the IBM PC.
Much like a modern solid state drive, the Interstellar Drive had no moving parts. It provided non-volatile data storage at speeds far greater than a hard drive (then commonly known as a Winchester drive) or a floppy drive. Advertisements described the Interstellar Drive as providing “five to fifty times faster performance than floppy disks and Winchester drives.”
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The FPS-3 was an unusual hardware add-on for the TRS-80 Model III and Model 4 that gave users the ability to make backup copies of their copy protected TRS-80 programs. It was created by Steve Sawyer and sold for $50.00 through his company J.E.S. Graphics of Tulsa, Oklahoma.
Most products that could defeat TRS-80 copy protection, such as Super Utility or Trackcess, were software that used the TRS-80 hardware to make exact copies of protected disks or tapes. This didn’t always work depending on the type of protection used. The most notable example was Super Utility, which couldn’t be used to make copies of itself!
Rather than use this approach, the FPS-3 was hardware that made copies of the data that a protected program loaded from disk or tape. It could create an exact snapshot of a program immediately after it had loaded into memory. As long as the protected program loaded completely from disk or tape with no overlays (as most did), the FPS-3 could be used to create an unprotected copy.
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The TRS-80 Micro Computer System Desk (catalog number 26-1301), also known as the TRS-80 System Desk, was Radio Shack’s recommended desk for the TRS-80 Model I. It was introduced in 1978 for a price of $199.00.
The TRS-80 System Desk was designed to hold a Model I, monitor, Radio Shack Expansion Interface, up to four floppy drives, and a TRS-80 Quick Printer, with all wiring hidden inside the desk. As one advertisement stated, the TRS-80 System Desk “concentrates your expanded TRS-80 system into one convenient area.”
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The Hurricane Labs Compactor was part of a series of products that modified the TRS-80 Model III to allow it to run CP/M programs. Hurricane Laboratories, better known as Hurricane Labs, was founded by Ronald L. Jones, a member of the Homebrew Computer Club who had a great deal of experience with CP/M.
There were three Compactor products for the TRS-80 from Hurricane Labs, all designed by Ron Jones:
- The Compactor I, introduced in late 1981, sold for $450.00, including a customized version of CP/M. It converted the Model III into a 48K CP/M computer.
- The Compactor II was introduced in late 1982. It added the same features as the Compactor I, but also doubled the Model III speed using a 4 MHz Z80A processor. The Compactor II included an extra 64K of memory to create a 112K CP/M computer. It also provided a real-time clock with battery backup. I have never seen a reliable price for the Compactor II.
- The Compactor IV wasn’t a CP/M board, but an 80 by 24 video board. It cost $475.00 and installed in place of the Model III RS-232 board. The Compactor IV emulated a Lear Siegler ADM-3A terminal, with reverse video, underline, and blinking. It also included a serial port to replace the one normally provided by the stock RS-232 board.
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Plug ’n Power was Radio Shack’s brand name for products that used the X10 power line communications protocol. X10 was developed in 1975 by Pico Electronics, Ltd. of Glenrothes, Scotland. Radio Shack, along with Sears, Roebuck & Co. (with the Sears Home Control System) and BSR (with the BSR System X-10), was among the first sellers of X10 compatible products.
Radio Shack introduced their first Plug ’n Power products in late 1979. Most of the products were appliance and light modules. These plugged into an electrical outlet, and an appliance or light was then plugged into the module. Some of those modules included:
- Appliance Module (catalog number 61-2681) cost $16.99 (originally $15.99)
- Lamp Dimmer Module (catalog number 61-2682) cost $16.99 (originally $15.99)
- Universal Appliance Module (catalog number 61-2684) cost $17.99
- Wall Switch Module (catalog number 61-2683) cost $17.99
- Wall Outlet Module (catalog number 61-2685) cost $21.95
The modules were designed to respond to commands sent over the electrical wires inside the house. They could turn on or off, or in the case of a lamp, change brightness. The advantage of using a power-line communication system was that it didn’t require any additional (and costly) signal wiring.
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The Shuffleboard and Shuffleboard III were CP/M hardware add-ons for the TRS-80 Model I and Model III. Although somewhat different products, each allowed unmodified CP/M programs to run on the TRS-80 by “shuffling” the TRS-80 memory map into one acceptable to CP/M.
Both the Shuffleboard and Shuffleboard III were created by Parasitic Engineering, but the Shuffleboard III achieved most of its popularity after Memory Merchant took over the product.
The original Shuffleboard was actually a companion to another Parasitic Engineering product, an 8" drive interface called the Maxi-Disk. Howard Fullmer and Gene Nardi created the Shuffleboard and Maxi-Disk and introduced them in May 1979 at the Fourth West Coast Computer Faire in Los Angeles, California.
The $995.00 (later $1079.00) Maxi-Disk consisted of two parts:
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The MISOSYS Hard Drive Kit was a hard drive interface for the TRS-80 Model III, Model 4, and Lobo MAX-80. (There was no version for the TRS-80 Model I.) It was announced in the Spring/Summer 1989 issue of The MISOSYS Quarterly and began shipping in September 1989. It came in in two configurations: 20 MB and 40 MB.
Although Roy Soltoff described the MISOSYS Hard Drive Kit as a “pre-assembled kit,” it came fully assembled, tested, and ready to connect to the TRS-80. The only other item needed was the “host interface cable” which cost $20.00 extra originally but was later included in the package.
The complete unit was housed in a 5.5" high, 7" wide, and 15" deep case, which had room for two half-height drives. The case contained a 60-watt power supply and fan. The shipping weight of the entire package was 20 pounds.
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The Holmes Sprinter was a family of speed-up boards for the TRS-80 Model I and III. They were created and sold by Holmes Engineering, Inc., a company responsible for many hardware add-ons for the TRS-80, such as the Expansion Mainframe, the VID-80, and the Internal Memory. The Sprinter models were probably the most popular speed-up boards available for the Model I and III.
The Sprinter I for the TRS-80 Model I was introduced in late 1981. It cost $99.50, which was more expensive than its primary competitor, the Archbold Speedup Board. However, the Sprinter I had one big advantage over the Archbold Speedup Board: it could be installed with no soldering at all. Installation required just a few steps:
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The Omikron Mapper was the first (and probably most popular) CP/M hardware add-on for the TRS-80 Model I and Model III. It allowed unmodified CP/M programs to run on a TRS-80, something not normally possible. The Omikron Mapper was introduced in 1979 by Omikron Systems, a Berkeley, California company run by George Gardner.
Omikron Systems sold three versions of the Omikron Mapper from 1979 to 1984:
- The original Omikron Mapper I was for the Model I. In 1979, it cost $169.00 for a version that could use 5 1/4" floppy drives. A version that could use 8" drives cost $199.00.
- The Omikron Mapper II was a data separator that allowed a Model I with Expansion Interface to run CP/M using a combination of 5 1/4" and 8" drives. In 1980, it cost $99.00. Omikron originally bundled the Mapper I as part of the Mapper II, but later sold them separately. In addition to CP/M, NEWDOS/80 could also use the Mapper II to access 8" drives.
- The Omikron Mapper III was for the TRS-80 Model III. Unlike the Mapper I, it only supported 5 1/4" drives. It cost $199.00 in 1983.
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After the Radio Shack TRS-80 Model I was introduced in 1977, many companies were said to be developing an interface to allow the Model I to use the wide selection of S-100 hardware available at the time. HUH Electronics of San Mateo, California was one of the few companies (if not the only) to actually release a S-100 interface. Their Model 8100, introduced in November 1978, had six slots to allow up to six S-100 devices to be connected to the Model I.
The S-100 bus standard was created by MITS in 1975 for their Altair 8800 computer. The Altair 8800 was designed with one mainboard with five 100-pin edge connectors. These connectors were used to attach the CPU, memory, and other peripherals to the Altair. These connectors followed a standard that became known as the “Altair bus.” Many people started creating and selling hardware designed to plug into the Altair bus. Competing computers, such as the IMSAI 8800, also used the standard, but under the name “S-100 bus.”
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The TRS-80 Model I, unlike some other contemporary computers, offered no way to install expansion cards internally. The Model I did have an expansion bus connector which allowed users to attach external hardware devices, such as the Radio Shack Expansion Interface. But the single connector meant that only one hardware device could be attached to a Model I at a time.
The Expandabus from Alpha Products, introduced in 1981, provided a way for TRS-80 Model I owners to connect multiple devices to the expansion bus, allowing up to five devices to be connected to a single Model I.
The Expandabus was similar to the T-Buss, which was one of the first TRS-80 items Alpha Products sold. The T-Buss cost $80.00 and allowed five devices to be connected to the Model I. The Expandabus was more flexible and available in four versions:
- the X2-40 for $29.00, which could connect two devices.
- the X3-40 for $44.00, which could connect three devices.
- the X4-40 for $59.00, which could connect four devices.
- the X5-40 for $74.00, which could connect five devices.
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The Seatronics Super Speed-Up was the fastest commercially available speed-up board for the TRS-80 Model 4. It could double the Model 4 speed to 8 MHz, without requiring any performance sapping memory wait states. The Super Speed-Up was sold by Seatronics, a company based in Maastricht, Holland, for $129.00. (A review in 80 Micro identified Sylvester Technologies of Cypress, Texas as the United States distributor, but that appears to have been a mistake.)
The Super Speed-Up was also available for the TRS-80 Model I and Model III, but the Model 4 version was the most common.
Installation of the Seatronics Super Speed-Up was more involved than other Model 4 speed-up boards. The first step of the installation was simple, consisting of removing the Z80 and plugging the Super Speed-Up board in its place. But subsequent steps involved cutting pins, moving wires, straightening a pin, running a wire, and possibly soldering a resistor. David Dalager in Computer News 80 described the installation as “not for the average computer user.”
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The Network 4 was a classroom networking system sold by Radio Shack that was popular in computer labs in the mid-1980’s. It allowed one computer used by a teacher to be connected to up to 63 student computers. The Network 4 was based around the TRS-80 Model 4, well after MS-DOS computers became more common. It was probably one of the biggest reasons the TRS-80 Model 4D remained in the Radio Shack catalog until 1990.
In the early days of microcomputers, schools were viewed as a major market for computers. The Radio Shack Education Division, formed in 1980, aggressively promoted the use of computers in schools. In 1985, they stated that “Radio Shack is the leading marketer of microcomputers to schools, with more TRS-80 computers in America’s schools than any other brand.”
Radio Shack had been pushing the idea of connecting computers in schools since 1980 under the name “TRS‑80 Network”:
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The Super4 was a popular speed-up board for the TRS-80 Model 4. Introduced in 1984 by Alpha Technology, Inc. (not to be confused with Alpha Products), the Super4 was both inexpensive and easy to install. As the advertisements stated, it required “No trace cutting. No soldering. No wires to connect.”
The Super4 package contained everything necessary for the speed-up, including a faster Z80 chip. Installation consisted of unplugging the 4 MHz Z80 CPU from the Model 4 and plugging the Super4 into the now empty Z80 socket.
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The XLR8er (pronounced accelerator) was a speed-up and memory expansion board for the TRS-80 Model 4, regarded by many to be the ultimate Model 4 expansion. The XLR8er replaced the Model 4 Z80 CPU with an enhanced microprocessor that offered 256K of additional memory (for a total of 384K) and up to double the speed. The XLR8er originally sold for $299.95 (with memory) when H.I. Tech, Inc. introduced it around 1986, but that price soon dropped to $249.95.
The XLR8er hardware was based on the SB-180 single-board computer project that was presented by Steve Ciarcia in the September and October issues of BYTE and sold by MicroMint. The XLR8er was close enough to the SB-180 design that it was able to accept “Ciarcia” expansion modules designed for the SB-180.
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The MegaMem, introduced in early 1990 by Anitek Software Products, was the ultimate memory upgrade solution for the TRS-80 Model III and 4. By using the same high capacity SIP (single in-line package) memory modules used in PC compatibles at the time, the MegaMem allowed a Model 4 to be upgraded as high as 8MB. Unlike the HyperMem, an earlier Anitek memory upgrade product, the MegaMem required no soldering, trace cutting, or other surgery to the computer. Peter Ray, the president of Anitek, described the MegaMem as the upgrade for “people who can spend extra money and hate soldering.”
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Like many personal computers at the time, the TRS-80 Model I had fairly primitive built-in sound capabilities. That changed in 1980 with the introduction of the Orchestra-80, a small $79.95 unit that plugged into the TRS-80 and could play music with four simultaneous voices over a six octave range. Orchestra-80 was sold by Software Affair, Ltd., a company created by Bryan Eggers and Jon Bokelman. It became one of the best remembered hardware add-ons for the TRS-80.
Orchestra-80 had predecessors in two earlier kit products for S-100 computers. In 1977, Software Technology Corporation introduced the STC Music System, which featured “Musical Arrangements by Jon Bokelman.” In 1979, after the STC Music System was no longer available, California Software Co. introduced the Software Music Synthesis System. Also created by Jon Bokelman, the Software Music Synthesis System, or SMS, maintained the same syntax as the STC Music System, even though it was a completely different product.
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The TRS-80 Multi-Pen Plotter (catalog number 26-1191) was similar to the earlier TRS-80 Plotter/Printer (catalog number 26-1190), but offered one important new feature: the ability to print in color. Described as an “intelligent plotter,” the Multi-Pen Plotter used replaceable colored pens to print on paper or transparencies. Even at a price of $1995.00, the Multi-Pen Plotter was cheaper than many other color output alternatives available at the time. In fact, the catalog description states that the Plotter “brings an affordable price to color graphics!”
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The TRS-80 Digitizer (catalog number 26-1195), available in November 1981, provided a way to digitize maps, blueprints, and charts in an era before document scanners were affordable or commonly available. The Digitizer, which measured 2¼″ by 15½″ by 4¼″, cost $449.00 and connected to the TRS-80 Model I or Color Computer through the cassette port or to other TRS-80 models through the RS-232 port. (Oddly, the Model III couldn’t be connected through the cassette port like the Model I.)
The manual described the concept behind the TRS-80 Digitizer:
What exactly is a digitizer? Basically, it’s a device that describes a specific point on a sheet of paper in terms of its X-Y (Cartesian) coordinates. For example, if you didn’t have a Digitizer and you wanted to describe the location of a particular point on an 8 1/2" X 11" sheet of paper, you would need to measure how far from the left edge that point is, then how far from the top edge it is.
A digitizer does this for you. It tells you how far horizontally (the X-axis) and how far vertically (the Y-axis) that point is from the edge of the paper.
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The Radio Shack Network 3 Controller (catalog number 26-1212) was a networking system designed for use in classrooms. First appearing in the 1983 catalog, the Network 3 Controller cost $599.00. Unlike the earlier Network I> and Network 2 Controllers, which worked with more than one type of TRS-80 computer, the Network 3 Controller only supported the Model III or Model 4 in Model III mode.
From the description in a 1983 Radio Shack catalog:
The Network 3 Controller enables up to 16 Model III student stations to choose from lessons stored on a teacher’s “host” system. This frees the instructor from repeatedly loading programs into individual stations. And scores are automatically stored on the host disk for later review as lessons that generate student record keeping are completed. The Network 3 also allows computer science students to learn Disk BASIC on a non-disk Model III. That means you get the features of a disk-equipped computer, but at about half the price!
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The TRS-80 PT-210 Portable Terminal (catalog number 76-1001) was a mobile dumb terminal that provided a way for travelers to access remote computers while on the road. Introduced by Radio Shack in late 1982 for a price of $995.00, the PT-210 was promoted with the slogan “Now there’s a TRS-80 you can take with you on business trips!”"
The PT-210 weighed 15 pounds and came in a briefcase-style case. It contained a full-size 53-key keyboard, an acoustic coupler that communicated at 110 or 300 baud, and a “whisper-quiet” thermal printer. The catalog description stated:
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The Radio Shack Network I Controller (catalog number 26-1210) was an early networking system for the TRS-80. Introduced on March 1, 1980, the Network I Controller (originally called the TRS-80 Model I Network I) cost $499.00 and was primarily designed for classroom use.
The Network I concept, described as “teacher-centric,” was based around a disk-based Model I (used by a teacher) connected through a Network I Controller and cassette cables to cassette-based Model I’s (used by students). Up to sixteen student computers could be connected over a distance of up to thirty feet. From the announcement in the TRS-80 Microcomputer News:
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The TRS-80 Model 4, introduced in 1983, was 100% software compatible with its predecessor, the TRS-80 Model III. A cassette-based Model 4 behaved identically to a cassette-based Model III and could run all Model III software. But a disk-based Model 4 could also run new Model 4 software that exposed features unique to the Model 4, such as extra memory and a larger text resolution. For Model III owners who wanted to run the new software but were unwilling to discard their Model III, Radio Shack offered the Model III to 4 Upgrade Kit.
The Model III to 4 Upgrade Kit (catalog number 26-1123) originally cost $799.95 and was introduced at the same time as the Model 4. It could convert a disk-based Model III into a disk-based Model 4, capable of running all Model 4 programs. One early Model 4 advertisement stated that “Model III disk system owners can get all the new Model 4 features by adding our upgrade kit.”
The Model III to 4 Upgrade Kit consisted of several parts:
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Mayday was a line of uninterruptible power supplies for the TRS-80 and other computers. It was sold by Sun Research (originally Sun Technology), a division of Phase-R Corporation.
Phase-R Corporation was located in New Durham, New Hampshire and experienced frequent problems with poor power quality and frequent outages. They originally developed the Mayday to protect the office TRS-80’s, describing it as “designed and developed using a complete TRS-80 system.” Sun Research introduced the first Mayday model in 1980.
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Street Electronics Corporation sold a variety of speech synthesizers with the Echo name. The Echo II, the Apple II version, was the most popular, but they also sold versions for other computers. As of 1982, there were four versions:
- Echo-80 for the TRS-80 Model I and III
- Echo II for the Apple II
- ECHO-100 for S-100 computers
- ECHO GP (General Purpose) for any computer with a RS-232 or parallel printer port (including a TRS-80)
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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 6800 computers. 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:
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The E/RAM was a high-resolution add-on for the TRS-80 Model I. Introduced in 1980 for a price of $349.95, the E/RAM was designed and manufactured by Keyline Computer Products from Tulsa, Oklahoma. It was sold by Vern Street Products, also in Tulsa.
The E/RAM (an acronym for Extended Random Access Memory) contained 6K of video memory. It increased the TRS-80 graphics resolution to 256 by 192, with the high-resolution graphics overlaying the text screen. The graphics could be enabled and disabled using either software or a hardware switch.
The E/RAM came in a steel case measuring 2 1/2″ high, 6″ wide, and 12″ deep. The self-contained unit sat next to the Model I and installed in a straightforward way:
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The SubLOGIC 50/T80 was a high-resolution add-on for the TRS-80 Model I. It was created by SubLOGIC, a company better known to TRS-80 users for their T80-FS1 Flight Simulator.
Here is the text of the 1980 product introduction:
The SubLOGIC 50/T80 system is a high performance professional graphics display system designed to be used directly with the TRS-80. It provides the high-resolution graphics capability which the 80 lacks—the kind of graphics needed for scientific, engineering, and educational applications. Dense drawings, graphs, and even alphanumerics can be put on the 50/T80’s 256 by 240 dot screen. The 50/T80 has the support of SubLOGIC’s 2D and 3D graphics packages, which are powerful and easy to use. They operate easily from BASIC as well as assembly language.
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The Model 4 Grafyx Solution was the most popular high-resolution add-on for the TRS-80 Model 4, and probably the most popular Model 4 add-on in general. It was introduced in 1984 for a price of $199.95 by Micro-Labs, creators of the earlier Model III Grafyx Solution. The Model 4 Grafyx Solution provided true high-resolution access to every pixel on the 640 by 240 Model 4 display, yet was easily user-installable in only a few minutes.
Unlike the Model III Grafyx Solution, which was memory mapped, the Model 4 Grafyx Solution was port-mapped. It used the same ports and mapping as the Radio Shack Model 4 high-resolution board. This meant that the Model 4 Grafyx Solution was almost completely compatible with the Radio Shack board and they could run the same programs. This had the odd side effect of making the Model 4 Grafyx Solution in Model III mode incompatible with the Model III Grafyx Solution.
The Model 4 Grafyx Solution had many advantages compared to the Radio Shack board:
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The TRS-80 VOXBOX (catalog number 26-1181) was an early microcomputer speech-recognition product for the TRS-80 Model I. Introduced in July 1979 by Radio Shack for a price of $169.95, the VOXBOX was described as “electronic ears for your Model I.” The VOXBOX was only available for the Model I; there never was a version for the Model III.
Here is a description of the VOXBOX from a 1980 Radio Shack catalog, where it was paired with the $399 TRS-80 Voice Synthesizer:
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Radio Shack introduced the TRS-80 Microcomputer System, later known as the Model I, in August 1977. It was the first member of the original line of TRS-80 computers. Radio Shack followed the Model I with the mostly compatible Model III in 1980 and then the Model 4 in April 1983. But other than the transportable Model 4P in November 1983 and the improved Model 4D in 1985, there were no further members of this computer family.
Around the time of the development of the Model 4, Radio Shack engineers did plan a computer that could have followed it. Although not known by the name within Radio Shack, this often rumored computer was usually called the “Model 5” or the “Model 4C” by the public.
By considering all of the available bits of information, it is possible to piece together details about the key features of the “Model 5”:
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Radio Shack introduced their high-resolution add-on for the Model 4 (catalog number 26-1126) on October 15, 1983. Just like their Model III high-resolution board, it was never identified by name in any Radio Shack catalog. The official name seems to have been “TRS-80 Model 4 Computer Graphics” but it was usually referred to as the “Radio Shack Model 4 high-resolution board.”
At $249.95, the Model 4 high-resolution board was $80 cheaper than the Model III version. It provided a nearly identical hardware interface to the Model III version, with the same 640 by 240 resolution. It’s interesting to note that the Macintosh screen at the time was 576 by 340.
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The Model III Grafyx Solution was a high-resolution graphics add-on for the TRS-80 Model III. Created by Ted Carter, president of Micro-Labs, the Grafyx Solution was introduced in early 1982 for a price of $299.95. There never was a Model I version of the Grafyx Solution.
The Model III Grafyx Solution used a different approach than 80-GRAFIX, an earlier Micro-Labs product for the Model I and III. While 80-GRAFIX could only simulate high-resolution graphics by redefining the character set, the Grafyx Solution provided full access to the 512 by 192 resolution of the Model III.
No soldering was required to install the Grafyx Solution. Instead, installation consisted of plugging the Grafyx Solution into the Model III and using special micro-clips to attach it to specific pins on chips already in the Model III.
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Radio Shack introduced their high-resolution add-on for the Model III (catalog number 26-1125) on December 30, 1982 for a price of $369.95. It was never identified by name in any Radio Shack catalog but the official name seems to have been “TRS-80 Computer Graphics Package.” Few ever used that name and it was commonly referred to as the “Radio Shack high-resolution board.”
The Model III high-resolution board offered a resolution of 640 by 240. This was the same resolution as the Model II high-resolution add-on that Radio Shack had introduced the previous year, but it was higher than the normal Model III resolution of 512 by 192. There were so many similarities to the Model II high-resolution add-on that I suspect it was the basis for the Model III version.
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The Alpha Technology Supermem was one of the most popular memory expansion options for the TRS-80. Alpha Technology (not to be confused with the similarly named Alpha Products) introduced the Supermem in 1985 for the Model I, Model III, and Model 4 in four memory sizes:
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The TRS-80 Voice Synthesizer (catalog number 26-1180) was a speech synthesizer unit sold by Radio Shack. Introduced in 1979 for a price of $399.00, the unit was only compatible with the TRS-80 Model I; Radio Shack never sold a TRS-80 Model III version.
The TRS-80 Voice Synthesizer plugged directly into the Model I expansion port and worked with both Level I and Level II BASIC systems. Like most voice synthesizers at the time, it worked by outputting words already broken into phonemes, or very small units of sound. It was described this way by the product introduction (under the headline of “Your TRS-80 Speaks!”):
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The FASTLOAD cassette interface used a novel (and patented) method of speeding up loading cassette programs on a TRS-80 Model I. By using a specially modified cassette recorder permanently in fast-forward mode (the equivalent of the fast-forward button always being pressed), FASTLOAD increased cassette loading speeds up to sixteen times to as high as 8000 baud. FASTLOAD was introduced in 1981 by Personal Micro Computers, Inc. (also known as PMC) for a price of $188.00. The modified CTR-41 cassette recorder, required to use FASTLOAD, cost $95.00. Personal Micro Computers also sold FASTLOAD as an option for their PMC-80 and PMC-81 Model I compatible computers.
The FASTLOAD cassette interface connected to the Model I I/O connector and used a built-in ROM to add a new cassette loading routine (mapped to the LOAD command), keyboard debounce routine, automatic key repeat, and a key click feature. Upon startup, a single SYSTEM command was required to enable the FASTLOAD interface routines.
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The Holmes VID-80 was a popular add-on for the TRS-80 Model I and III. Introduced by Holmes Engineering, Inc. in 1982, the VID-80 offered two related features:
- It expanded the TRS-80 screen from 64 characters wide by 16 characters high to the larger 80 characters wide by 24 characters wide.
- It changed the TRS-80 memory map to allow running the CP/M operating system.
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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.
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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:
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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:
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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.
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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!
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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.
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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.
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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.
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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
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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:
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The LX-80 was an alternative to the Radio Shack Expansion Interface that took a different approach to compatibility than the competition. It was originally announced by Lobo Drives International in Fall of 1979, but problems with the supplied operating system meant that it wasn’t released until closer to 1981. The original price was $799 (without memory), although that price had been reduced to $510.00 by late 1982. Lobo Drives also briefly advertised the LX-50, but it is unclear how that differed from the LX-80.
The LX-80 unit was extremely solid (constructed of 1/8″ thick steel) and was designed to have the Model I monitor rest on top. Although more expensive than other Expansion Interfaces, the LX-80 came with an impressive set of features:
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The LemonAid Loader was a device which greatly improved the ability of the TRS-80 to load programs using a CTR-80 or CTR-80A cassette recorder. It was designed by Wayne Lemons and sold through his company, Lemons Tech Services. The LemonAid Loader was available in two versions: the original which cost $12.99 (later $19.99) and a “deluxe” improved version which cost $18.99 (later $23.50). Both versions were compatible with the Model I and Model III, although cassette filtering was especially useful on the Model I.
The LemonAid Loader was described this way by a product announcement:
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The SmartWatch was a single-chip clock/calendar add-on that could be used by many computers, including the TRS-80 Model I, III, and 4. The SmartWatch chip, a Dallas Semiconductor DS1216E, worked by replacing a 28-pin ROM and plugging the chip into its socket. Installation varied depending on the computer, but the general steps were simple:
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BIGMEM was a modification for the TRS-80 Model I which increased available memory. It was introduced by Microhatch in early 1982 for $180.00, but the price was reduced to $169.00 by late 1983. Microhatch also sold a utility disk (with print spooler) for $20.00 which could be bundled with BIGMEM. For any user unwilling to perform the modification, Microhatch would install BIGMEM for $199.00.
Much like the Holmes Internal Memory, BIGMEM replaced the 16K RAM chips inside the Model I with higher-capacity 64K chips. This avoided the reliability problems of the external memory in an Expansion Interface and also worked better with most speed-up kits.
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The Disk-80 was an alternative to the Radio Shack Expansion Interface that was sold by Micromint Inc. It was designed by Steve Ciarcia and was featured in his “Ciarcia’s Circuit Cellar” column in the March 1981 issue of Byte.
The Disk-80 was sold in several configurations:
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The Percom Doubler was the first successful double-density add-on for the TRS-80 Model I. It was introduced in 1980 by Percom Data Company for an initial price of $219.95. The Doubler hardware was designed by Wayne Smith and Harold Mauch (president of Percom) and the accompanying software was written by Jim Stutsman.
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The Patch was a unique all-hardware approach to implementing lower case on a TRS-80 Model I. It was sold by CECDAT Inc. for a price starting at $69.97.
The normal approach to adding lower case involved a hardware modification plus a software driver. Radio Shack never added a lower case driver to the Model I ROM, so the separate driver was required to enable generation of lower case characters. The lower case driver was stored in RAM, so it needed to be loaded again from cassette or disk every time the Model I was used.
The Patch combined an ordinary lower case hardware modification with a “patch” to the Model I ROM that added a lower case driver. Probably the best description of how it worked comes from one of their advertisements:
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The TRX-280 was a proposed motherboard replacement for the TRS-80 Model 4, described in the December 1990 issue of Computer News 80 and issue 38 of TRSLINK. It was created by Peter Ray of Anitek Software Products in an attempt to design a “next generation” TRS-80.
The TRX-280 design was based around the Z280, an enhanced Z80 compatible processor created by Zilog. The Z280 was an interesting chip, providing software compatibility with the Z80 yet adding many new features, such as a memory management unit, new addressing modes, and new instructions. It was also faster than the Z80 at the same clock speed.
The TRX-280 was planned as a drop-in replacement for the Model 4 motherboard (and possibly the Model III as well). It would have remained compatible with all TRS-80 software and hardware, with the one exception that it would have lacked a cassette port.
The TRX-280 had an impressive set of proposed features:
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The LNW System Expansion was a popular alternative to the Radio Shack Expansion Interface. Introduced in 1979 by LNW Research, the System Expansion was the most popular of the Expansion Interface replacements. LNW Research later described themselves as “the number one manufacturer of system expansion units and accessories for the Model I computer”.
The LNW System Expansion sold for $69.95 as a kit with a bare printed circuit board and manual. LNW later introduced the $399.95 LNW System Expansion II, which provided the same features but came assembled in a metal case.
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The Color-Graf was a color graphics interface for the TRS-80 Model I and Model III. Sold by Solectronics, the Color-Graf originally cost $260.00 for the Model I version. That price was later reduced to $195.00 for the Model I version and $235.00 for the new Model III version. Solectronics advertised the Color-Graf from 1982 to 1983.
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The Mikrokolor was a color graphics interface for the TRS-80 Model 100 that was sold by Andreasen’s Electronics Research & Development, Inc. The Mikrokolor hardware was designed by Paul Andreasen, the digital interface and graphics routines created by James Cole, and the software written by Andrew Baird. Andreasen’s Electronics Research & Development also sold versions of the Mikrokolor for the Model I, Model III, Model 4, and Model 12 and also the S-100 bus and the Apple II. There was also a $54.00 VHF modulator for the Mikrokolor that operated on channels 7 to 10.
The Mikrokolor fit into much the same category as the later Disk/Video Interface sold by Radio Shack, allowing a Model 100 to be used with a separate monitor. Unlike the Disk/Video Interface, which was black and white only, the Mikrokolor displayed in color.
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The TRS-80 Model I ran at a speed of 1.77 MHz. That speed was quite fast for a microcomputer at the time, but almost immediately people began designing speedup boards to increase it. The most famous of those speedup boards was the Archbold Speedup Board, designed by Bill Archbold and sold by Archbold Electronics.
The Archbold Speedup Board itself was a fairly small board (1.5" by 2.5"). It came with an instruction manual containing complete installation directions, including a photo of the Model I logic board. The exact installation procedure varied depending on the hardware installed but involved soldering wires to various points within the Model I and cutting a few traces.
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Although the TRS-80 Model I supported up to 48K of memory, there were only sockets for 16K within the Model I itself. The only official way to add more memory was to buy the Radio Shack Expansion Interface, which had sockets for an additional 32K of memory, for 48K in total. The Expansion Interface (without any memory) cost $299.00, making any kind of official memory expansion very expensive.
The other important feature of the Expansion Interface was the built-in floppy disk controller. But not everyone was interested in or could afford floppy drives, which cost hundreds of dollars per drive. Many people used cassettes or other alternative storage devices, such as the Exatron Stringy Floppy, the TC-8, or the BETA-80. What option was there for the Model I user who wanted to maximize memory but without the extras (and expense) of the Expansion Interface?
One answer was the Internal Memory, introduced by Holmes Engineering in 1981. Designed by Larry Holmes, the Internal Memory added memory entirely inside the Model I without requiring an Expansion Interface. It could be easily installed by the user without any soldering or trace cutting. The Internal Memory came in three versions:
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The TRS-80 Model I was designed to allow for external expansion through what Steve Leininger described as an “expansion port” (the TRS-80 card edge connector). Many people assumed that Radio Shack was developing a S-100 based expansion box to attach to the Model I. (The S-100 was a popular bus standard at the time.)
The first issue of the Radio Shack Microcomputer Newsletter in late 1977 contained a section answering some common questions about the new TRS-80 computer. One answer gave some details about the upcoming “expansion box”:
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Micromint sold several products for the TRS-80 that were based on designs that Steve Ciarcia had presented in his Ciarcia’s Circuit Cellar column in Byte magazine. The Micromint E-Z Color was a color graphics interface for the TRS-80 Model I and Model III that was based on his August 1982 column. In addition to the TRS-80 version, there were also versions of the E-Z Color sold for the S-100 bus and the Apple II.
The TRS-80 version was available in two configurations:
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The Radio Shack TRS-80 Model I had few options for internal expansion other than adding a maximum of 16K of internal memory. The external expansion possibilities were reserved for a device Radio Shack called the Expansion Interface.
The Radio Shack Expansion Interface plugged into the back of the Model I using a six-inch long cable and was designed to serve as a base for the TRS-80 monitor. It provided:
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Probably the most popular of the TRS-80 Model I and III color add-ons was the CHROMAtrs, introduced by South Shore Computer Concepts starting in 1982. It was available in several configurations:
- a kit without case or power supply cost $99.00
- a kit with case and power supply cost $129.00
- a fully-assembled and tested unit cost $169.00
Each CHROMAtrs unit supported both the Model I or Model III and would work with either computer using the proper cable. The Model III cable would also work with the Lobo MAX-80 with a few minor modifications.
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The Radio Shack Expansion Interface added single-density floppy disk support to the TRS-80 Model I. Floppy disks were a great improvement over cassettes. But many people reported problems with reliability, particularly when reading or writing lower disk tracks. CRC errors and locked out tracks occurred with disturbing regularity.
The Separator, sold by Percom for $29.95, fixed all of those problems. It provided a data separator with far higher resolution (16 MHz) than the separator used by the Expansion Interface (1 MHz). Good data separation was vital for isolating the clock and data pulses that made up a disk track.
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Back in the late 1970’s, the Apple II and the TRS-80 Model I were fierce competitors for computer sales. One advantage the Apple II had over the Model I was the ability to display color graphics. One of the first Model I productsto address this deficiency was the Percom Electric Crayon. Percom introduced the Electric Crayon in December 1979 for a base price of $249.00. It was featured on the cover of the January 1981 issue of 80 Microcomputing.
The Electric Crayon was a small (12 inch wide by 9 inch deep) box which output a composite video signal that could drive either a monitor or a television set. It connected directly to the TRS-80 printer port and was controlled using EGOS, a ROM-based operating system. EGOS was directly programmed using single character commands. Virtually unique among TRS-80 color add-ons, the Electric Crayon did not use the TMS9918 graphics chip and did not support sprites.
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The Mikeegraphic Graphics System was a high-resolution graphics add-on for the TRS-80 Model I and Model III. It was sold by Mikee Electronics Corporation for $340. Originally known as the Mikeeangelo when it was introduced in late 1981, the name was changed to Mikeegraphic just a few months later, presumably to avoid confusion with another product.
Unlike the 80-GRAFIX, which provided high-resolution using a programmable character generator, the Mikeegraphic used a true bitmapped graphics screen. The high-resolution screen was mapped in its entirety at the top of the TRS-80 memory.
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The Model III added some nice improvements to the Model I and boasted nearly complete compatibility. But there were still some areas of incompatibility. Considering that most TRS-80 software development moved to the Model III, it was understandable that some Model I owners felt left behind.
The Norcom TC-III was a $399.00 ($499.00 factory installed) motherboard replacement for the Model I that promised all Model III features right in the Model I case. It was sold by Northern Information Technology Corp. The advertisements touted the following features:
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There were quite a few different storage products available back in the early days of the TRS-80 Model I. In the long term, the floppy drive (and later the hard drive) completely beat out all of the competition. But back when floppy drives were considered too expensive by many, one of the most popular storage products for the TRS-80 was the Exatron Stringy Floppy.
Founded in 1974 by Robert Howell, Exatron was a supplier of automated test equipment for manufacturers and OEMs. Exatron first demonstrated the S-100 version of the Stringy Floppy at the West Coast Computer Faire in March 1978. The TRS-80 version was introduced in May 1979 at the San Francisco Computer Faire. An early price for a TRS-80 starter kit (Stringy Floppy, wafers, and software) was $299.50. The Stringy Floppy provided an additional cost savings over floppy drives because it didn’t require an Expansion Interface. By 1982, the price for a single Stringy Floppy drive had come down to $99.50.
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Over time, many Model I computers (particularly those with Expansion Interfaces) developed the annoying habit of spontaneously rebooting. The reason was simple: the Model I card edge connectors were solder-coated tin and had a tendency to oxidize over time. Oxidation interfered with the electrical connections and tended to cause reliability problems, particularly with the critical Expansion Interface cable.
I’m sure that anyone who used a Model I still remembers that the best to way to remove the oxidation was to use a pink rubber eraser to scrub the connectors. The usual recommendation was to clean the connectors every month but many people did it every week.
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Many people considered the lack of high-resolution graphics to be the biggest deficiency of the TRS-80 Model I. The maximum resolution of the Model I was 128 by 48 by using block graphics. Many games made good use of that resolution, but it was still low compared to other computers.
The 80-GRAFIX was one of several high-resolution add-ons available for the Model I. Designed by Ted Carter, it was originally sold by Programma International for $149. The 80-GRAFIX fit entirely within the Model I case and required only minimal soldering.
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ARCNET, which stands for Attached Resource Computer NETwork, is a networking standard that was created by Datapoint Communications in 1976. It was one of the first networking systems used by personal computers and provided a way for multiple computers to share printers and files. One of the primary advantage of ARCNET at the time was that it was substantially cheaper than its competitors, including Ethernet.
Radio Shack sold Arcnet cards and hardware for the Model II/12/16/6000 series starting in 1982. Arcnet cards were planned for the Model III and 4 but were never released. Two remnants of that planned support are the four functions labeled “Reserved for Arcnet” in the Programmer’s Guide to TRSDOS 6 and an Arcnet boot error message in the Model 4P ROM.
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One frequent criticism of the TRS-80 (especially the Model I) was the quality of the screen. Many complained of eyestrain and headaches after staring at the screen for a long time. Another frequent complaint was noticeable flicker, especially under poor lighting conditions.
One popular solution was the Soft-View replacement CRTs from Langley-St. Clair Instrumentation Systems, available for the Model I, Model III, Model 4, and Model 16. Their replacement CRTs used a slower-phosphor tube that was much easier on the eyes and virtually eliminated flicker. Here’s a quote from one of their advertisements:
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The Newclock-80 was a clock/calendar add-on for the TRS-80 released by Alpha Products in 1983. It replaced their TIMEDATE 80 clock/calendar but remained software compatible with it.
The Newclock-80 plugged into the expansion bus and required no hardware modifications. The price was $59.95 for both the Model I and Model III versions, a significant reduction from the $95 price of the TIMEDATE 80. The Model III version also worked on the Model 4. In 1985, the price of the Model I version was reduced to $39.95.
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The MicroMerlin (referred to in some advertisements as the µMerlin) was a MS-DOS compatible add-on for the TRS-80. It was released by Micro Projects Engineering in 1982 with a starting price of $1,195.00.
The MicroMerlin connected to the expansion bus of a computer and required no hardware modifications to the computer itself. It originally supported the Model I and Model III, but later also the Model 4 and LNW80. There were two hardware requirements:
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The first commercial joystick for the TRS-80, the STICK-80, was created by Alpha Products (originally Alpha Product Co.). The first advertisement I can find was in the December 1980 issue of
80 Microcomputing. The STICK-80 package included an Atari joystick and interface and originally cost $29.95.
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In 1981, Bill Hogue wrote
Robot Attack, a variation on the arcade game
Berzerk. Unlike most TRS-80 games, in
Robot Attack you can move and fire in all directions. You fire in a direction by moving the joystick in that direction and pressing the FIRE button. This shows up a problem with the STICK-80 mapping; how can a game determine if the player was moving the joystick up or down and firing if the
FIRE button is mapped to a combination of
UP plus
DOWN?
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In October 1981, Alpha Products created a new version of their joystick which included a mode switch to allow a choice between the STICK-80 and TRISSTICK
FIRE button behavior. The advertisements from then on referred to the joystick as the Alpha Joystick, and the price remained at $39.95.
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