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TRS-80

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The TRS-80 Micro Computer System was a groundbreaking desktop microcomputer.

Radio Shack Tandy TRS-80 Model I System
Radio Shack Tandy TRS-80 Model I System

It was developed by the American Tandy Corporation. The company sold these machines through its Radio Shack retail stores. Launched in 1977, it was one of the first mass-produced home computers. It was part of what experts call the "1977 Trinity."

Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image)
Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image)

This group included the Apple II and the Commodore PET. The TRS-80 was colloquially known as the "Trash-80." Later, the company renamed it the Model I to distinguish it from newer versions.

Technically, the system relied on the Zilog Z80 8-bit microprocessor.

Radio Shack Tandy TRS-80 Model I PCB
Radio Shack Tandy TRS-80 Model I PCB

This chip acted as the central processing unit for the machine. The standard configuration included 4 KB of DRAM, which is a type of short-term memory.

Radio Shack Tandy TRS-80 Model I Keyboard
Radio Shack Tandy TRS-80 Model I Keyboard

Users interacted with the computer through a full-stroke QWERTY keyboard. The video monitor displayed 64 characters per line.

TRS-80-graphics
TRS-80-graphics

To store programs, the original package included a cassette tape drive. The system also featured a Level I BASIC interpreter stored in ROM. BASIC is a programming language that allows users to give instructions to the computer.

Users could expand the basic system to increase its power. The RAM, or random access memory, could be upgraded to 48 KB.

Radio Shack Tandy TRS-80 Model I Level II ROM Upgrade PCB
Radio Shack Tandy TRS-80 Model I Level II ROM Upgrade PCB

The system also supported up to four floppy disk drives or hard disk drives. This expansion allowed the machine to handle more complex data. However, the Model I had some technical difficulties. These included keyboard bounce issues and a troublesome Expansion Interface. The process of loading and saving data via cassette tapes was also considered difficult. Until 1981, the machine lacked support for lowercase characters. This limitation sometimes made it harder for businesses to adopt the technology.

The development of the TRS-80 began in the mid-1970s. Don French, a Tandy buyer, began designing a computer after seeing a MITS Altair kit. He worked with John V. Roach, the vice president of manufacturing. They eventually hired Steve Leininger to provide technical expertise. Leininger had experience with the SC/MP microprocessor. While some at Tandy wanted to sell a computer kit, Leininger argued for a preassembled machine. He believed many people would find soldering parts together too difficult. In February 1977, they presented a prototype to Charles Tandy. During this test, the computer's Tiny BASIC implementation crashed. It could not process a large number when Charles Tandy typed in a salary. The team quickly added floating-point math support to the Level I BASIC to fix this.

Radio Shack announced the TRS-80 at a press conference in New York City on August 3, 1977. The basic system had a starting price of US$600.

Radio Shack Tandy TRS-80 Model I Rear Panel
Radio Shack Tandy TRS-80 Model I Rear Panel

This was a significant price for the time. Despite internal skepticism from executives, the public response was massive. After the announcement, 15,000 people called to purchase the unit. This volume of calls actually paralyzed the company's switchboard. Additionally, 250,000 people joined a waiting list with a $100 deposit. By the end of its lifetime, the company sold over 200,000 units. This success helped change the image of Radio Shack from a retailer of small electronics to a major computer provider.

The TRS-80 was a massive commercial success compared to its rivals. By 1979, it possessed the largest selection of software in the microcomputer market. An analysis showed that the TRS-80 outsold the Apple II by a factor of five until 1982. By 1981, InfoWorld described Radio Shack as the dominant supplier of small computers. The company used its thousands of stores to provide full-service support. Customers could receive upgrades, repairs, and training at local Radio Shack locations. This massive distribution network gave Tandy a huge advantage over competitors who lacked such widespread retail presence.

The product line evolved through several different models. In mid-1980, the company released the TRS-80 Model III, which was broadly compatible with the original. The Model I was discontinued shortly after, partly due to stricter US FCC regulations regarding radio-frequency interference.

TRS-80 Model 4 (modified)
TRS-80 Model 4 (modified)

In April 1983, the Model III was succeeded by the TRS-80 Model 4. Eventually, the name "TRS-80" became a generic brand for many unrelated products. These included the Model II, the Model 2000, the Model 100, the Color Computer, and the Pocket Computer. This evolution shows how one successful machine can lead to an entire family of different technologies.

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🖼️ Images & Media (10)
File:Radio Shack Tandy TRS-80 Model I System.JPG
Radio Shack Tandy TRS-80 Model I System.JPG
File:Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image).jpg
Home or Personal Computers from 1977 -...
File:Radio Shack Tandy TRS-80 Model I PCB.JPG
Radio Shack Tandy TRS-80 Model I PCB.JPG
File:Radio Shack Tandy TRS-80 Model I Rear Panel.JPG
Radio Shack Tandy TRS-80 Model I Rear Panel.JPG
File:Radio Shack Tandy TRS-80 Model I Level II ROM Upgrade PCB.JPG
Radio Shack Tandy TRS-80 Model I Level II...
File:Radio Shack Tandy TRS-80 Model I Keyboard.JPG
Radio Shack Tandy TRS-80 Model I Keyboard.JPG
File:TRS-80-graphics.svg
TRS-80-graphics.svg
File:TRS-80 Model 4 (modified).jpg
TRS-80 Model 4 (modified).jpg
File:TRS-80 Model 4P Crop Delsener.jpg
TRS-80 Model 4P Crop Delsener.jpg
File:DGT-100 Brazilian TRS-80 Clone.jpg
DGT-100 Brazilian TRS-80 Clone.jpg
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