The TRS-80 got its name from the Tandy, the company that manufactured the system, and Radio Shack, the company that sold it in stores. The "80" came from the original system's Z80 8-bit CPU made by a company named Zilog.
The TRS-80 Model 1 was the first home computer that Radio Shack introduced. It was developed by Don French and Steve Leininger. Unlike most home computers before it, the TRS-80 was not released as a kit; it came fully assembled. The monitor for the Model 1 was essentially an RCA black and white television without a tuner. The system featured 4KB RAM and 4KB ROM. The CPU was housed at the base of the 53-key keyboard. Included with the system was a game package featuring Blackjack and Backgammon. The introductory retail price for the TRS-80, with a monitor and the Realistic CTR-41 cassette tape drive, was $599.95. In its first year of existence, the TRS-80 sold over 50,000 units.
The Model 1's ROM contained 4KB of Level 1 BASIC. When it was released, several multimedia programs were available for the TRS-80 including Math I, Personal Finance and Kitchen. The TRS-80 Expansion Interface was required if users wanted to get optimal use from the system. It plugged into the back of the Model 1 with a ribbon cable and allowed users to upgrade to as much as 48KB RAM. It enabled the machine to use two cassette tape units, a printer, and as many as 4 floppy disk drives.
In May 1980, Tandy released the TRS-80 Model 2. It was the first computer in the upcoming TRS-80 business computer line. It featured a more powerful processor than the original along with 8-inch disk drives that allowed greater storage capacity.
In July 1980, the TRS-80 Model 3 was released. It was priced at $700 and was the second home computer that Tandy released. The CPU was not much different than the Model 1, however the monitor and keyboard were combined in a single housing. The cassette tape interface for the Model 3 could transfer data at a full 1500 baud compared to 500 baud with the Model 1. The Model 3 also featured two 5.25inch floppy disk drives.
Also in July 1980, the TRS-80 Color Computer was released in the United States. It carried a retail price of $399 and featured the Motorola 6809E chip. Included with it were 4KB RAM, 8KB BASIC, a 53-key keyboard and a built-in modulator to plug into a color television set.
In March 1983, Tandy released the TRS-80 Model 100. It became the world's first official laptop computer. The entire system (including screen) weighed 3.9 pounds. The Model 100 featured an LCD screen, a full 56-key keyboard, an internal 300 baud modem and a cassette tape drive. The system retailed for $799 with 8KB RAM and $1000 for the 24KB version. It ran on 4 AA batteries that would last close to 20 hours.
The same year, Tandy introduced the TRS-80 Model 4. It was compatible with the previous Tandy home systems but introduced a faster processor and a higher resolution display. The TRS-80 Color Computer 2 also debuted in 1983. Essentially it was an improved version of the Color Computer 1 but it was cheaper, featured a smaller case, had a more efficient power supply and a complete keyboard.
In 1986, the TRS-80 Color Computer 3 was released. Among the improvements it provided over its predecessors were a standard 128KB RAM (upgradable to 512KB) and an increased processing speed to 1.7MHZ.
Even though the line of TRS-80 computers were not as well publicized as its competitors like Commodore or Apple throughout the eighties, Radio Shack continued selling the TRS-80 until 1987. ~ Dave Beuscher, All Game Guide