TRS-80 Microcomputer System Model II

TRS-80 was a brand associated with several desktop microcomputer lines sold by Tandy Corporation through their Radio Shack stores. The original "TRS-80 Micro Computer System" launched in 1977 (later known as the Model I) was one of the earliest mass-produced personal computers. The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small-businesses. Tandy Corporation's leading position in what Byte Magazine called the "1977 Trinity" (Apple, Commodore and Tandy) had much to do with Tandy's retailing the computer through more than 3,000 of its Radio Shack storefronts. Notable features of the original TRS-80 included its full-stroke QWERTY keyboard, small size, its floating point BASIC programming language, an included monitor, and a starting price of $600[1] (equivalent to $2,230 in 2011). The pre-release price was $500 and a $50 deposit was required, with a money back guarantee at time of delivery. One major drawback of the original system was the massive RF interference it caused in surrounding electronics. Stricter FCC regulations on interference led to the Model I's replacement by the Model III.

By 1979, the TRS-80 had the largest available selection of software in the microcomputer market.

As well as the original Model I (and its compatible descendants), the TRS-80 name was later used as a generic brand on other technically-unrelated computer lines sold by Tandy, such as the TRS-80 Model II, TRS-80 Color Computer and TRS-80 Pocket Computer.

The Model II was introduced in May of 1979 and first shipped in October of 1979. The Model II, which included an 8" drive, sold for $3,450 and was a business computer.


CPU: Z-80A 8-Bit Processor (4.00 MHz)
RAM: 32K or 64K  
ROM: 2K (Bootstrapped ROM; Bank Switched out after Boot)
Language: Microsoft BASIC (not stored in ROM – but was, rather, a 17K interpreter that was ona disk that came with the computer. Since BASIC was not used for most Model II applications, it made more sense to put it on disk and load it only when necessary rather than put it on ROM and lower the RAM to 48K like they did with the Model I and Model III)  
Video: 12? monitor; 24 lines x either 40 or 80 characters text; 32 “Business Graphic” characters Keyboard: 76 Key including Numeric Keypad. Special keys include HOLD, ESCape, BREAK, CTRL, CAPS, REPEAT, Up, Down, Right, Left, F1 and F2.  
Expansion: Four plug-in card slots for future expansion or converting 32K to 64K.  
Storage: 8? SS/DD Floppy Drive (486,000 characters per disk)  
Storage Option: Expansion Unit which could house up to three additional 8" drives  
Storage Option: Up to 4 8.4MB Hard Drives  
I/O: RS-232C (2), Parallel/Printer (1), External Disk Bay Port (1)  
Subsystem: Direct Memory Access and Vectored Inputs  
Power: 120VAC 60Hz  
Dimensions: 14 x 21 1/4 x 23 1/2

Our unit has twin 8" disk drives was verykindly donated by Pat Dudman

Manufacturer: Radio Shack
Date: 1979

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TRS-80 Microcomputer System Model I Radio Shack 1st January 1979
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This exhibit has a reference ID of CH30931. Please quote this reference ID in any communication with the Centre for Computing History.


TRS-80 Microcomputer System Model II

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