Radio Shack TRS-80
(Model I)
Released:August 1977
Price:US $599.95 (with monitor)
How Many:200,000 (1977-1981)
CPU:Zilog Z-80A, 1.77 MHz
RAM:4K, 16K max*
Ports:Cassette I/O, video,
Expansion connector*
Display:12-inch monochrome monitor
64 X 16 text
Expansion:External Expansion Interface*
Storage:Cassette storage*
* Additional capabilties with Expansion Interface

RS=Radio Shack
80=Z-80 microprocessor

Where's the computer? It's in the keyboard! As one of the first home computers ever, the TRS-80 was a great success. Tandy wasn't expecting many sales, but this, their first computer, sold 10,000 units in the first month alone. It includes everything you need to have a real computer of your very own - the computer, monitor and cassette deck for loading and saving data.

Yes, these were the days when you bought, loaded and saved your data and programs on cassette tapes.

Floppy disk drives didn't come into common use until years later. Even then, they were very expensive, costing hundreds of dollars.

The TRS-80 Mini-Disk was available within a year of the TRS-80 microcomputer's release, but it cost $499, more than the computer itself.

Even three years later, in 1980, the TRS-80 floppy drive still costs about $425.

There aren't any internal expansion capabilities, but two versions were eventually released:
  • The first TRS-80 computers had no numeric keypad, and Level I BASIC with 4K RAM.
  • Later systems had an improved level II BASIC with 16K RAM, and a numeric keypad.

    The Level I to Level II upgrade includes attaching extra chips and wires to the motherboard - not for the amateur. Originally, Radio Shack would install the upgrade (after you purchased it) in your TRS-80 "at no extra cost to you!".

    Most serious users eventually purchased the $299 Expansion Interface, a well-designed and attractive external module which sits under the monitor.

    It offers many improvements over the basic TRS-80:
  • Printer port
  • Expansion port
  • Optional serial port
  • Up to 32K additional RAM
  • Two tape drive connectors
  • Signals for a real time clock
  • Floppy disk controller, up to 4 drives

  • It isn't perfect, though. The cheap and unreliable connection between the keyboard and the expansion interface often causes system crashes and lock-ups. One fix is to solder the connection, making it permanent and impossible to seperate the two.

    Is the TRS-80 a portable computer? Well, not really, but you CAN purchase official carrying cases from Radio Shack!

    1978 Order Worksheet for the TRS-80 and Peripherals

     4K Level-I
     26-1003 16K Level-I690.00
     26-1004 4K Level-II499.00
     26-1006 16K Level-II789.00
     26-1201 12" Video Display199.00
     14-841* Realistic CTR-41 Cassette Recorder49.95
     26-2101* Level-I User's Manual

    * Recorder and manual included free
     when computer is ordered with display
     16K Memory (RAM)
     26-1120 Level-II BASIC (ROM)

     These two options are installed by
     Radio Shack at no extra installation cost
     TRS-80 Expansion Interface
     26-1150* TRS-80 Line Printer1299.00
     26-1151 TRS-80 Screen Printer599.00
     26-1160* TRS-80 Mini-Disk (Requires 16K)

    * Requires Level-II BASIC, and
     Expansion Interface
     Payroll (up to 12 employees)
     26-1502 In-Memory Information19.95
     26-1601 Home Recipe4.95
     26-1602 Personal Finance14.95
     26-1701 Math I19.95
     26-1702 Algebra I19.95
     26-1703 Statistical Analysis29.95
     26-1801 Backgammon/Blackjack4.95
     26-1802 Quick Watson!4.95
     26-2001 T-BUG14.95
     26-2002 Editor/Assembler29.95
     26-2003 Level-I BASIC Course12.95

    By 1980, Radio Shack had released the new TRS-80 Model III. It is basically a super-Model I, with all of the Model I options built-in, including up to 48K RAM and two (optional) internal floppy drives.

    There was some controversy with this announcement, though.
    From the official "Radio Shack TRS-80 Microcomputer NEWS" newsletters:
    September 1980: "First of all the Model I is not dropped, it is in the 1981 Radio Shack Annual catalog and the price is unchanged."
    Then, just 4 months later:
    January 1981: "During November we had our annual shareholders meeting and it was announced that manufacturing of the Model I computer would stop prior to the end of 1980. meet the new FCC regulations we would have to redesign the entire product, case and all."

    The Model I failed the new FCC regulations about RF emissions generated by computers. It is unshielded and could cause interference on near-by radios and televisions.

    Related Links

  • TRS-80 Model I from Ira Goldklang's TRS-80 Revived Pages
  • TRS-80 Model I from
  • Tandy Catalog Numbers for Computers, Peripherals, and Software from Tim Mann's TRS-80 Page
  • A. Richard Miller's TRS-80

  • History of the Radio Shack Computers

    • 1921: - Radio Shack begins as a one-store retail and mail-order company catering to ham operators and electronics buffs.
    • 1963: - Charles Tandy buys the chain of stores, and within two years turned a $4 million dollar loss into a $20 million dollar profit.
    • 1977: August - Radio Shack announces the TRS-80 Model I microcomputer.
    • 1977: September - One month after launching the TRS-80, 10,000 are sold.
    • 1979: May - Tandy/Radio Shack announces the TRS-80 Model II.
    • 1979: October - Radio Shack begins shipping the TRS-80 Model II to users.
    • 1980: July - Radio Shack introduces the TRS-80 Model III, priced from US$700 to US$2500.
    • 1980: July - Radio Shack introduces the TRS-80 Color Computer, and sells for US$400.
    • 1980: July - Radio Shack introduces the TRS-80 Pocket Computer. Price is US$230.
    • 1981: January - Radio Shack ceases production of the TRS-80 Model I, and recalls units from the US market, due to failure to meet new FCC radio-frequency interference regulations.
    • 1982: January - Radio Shack introduces the TRS-80 Model 16, with 8-inch floppy drives, and optional 8-MB hard drive.
    • 1982: January - Radio Shack introduces the TRS-80 Pocket Computer, Model PC-2, for US$280.
    • 1983: March - Radio Shack announces its TRS-80 Model 100 portable computer. Price is US$799 for 8KB version, to US$1134 for the 32KB version.
    • 1983: May - Radio Shack introduces the TRS-80 Model 4, for US$2000.
    • 1983: October - Tandy/Radio Shack announces the "transportable" TRS-80 Model 4P, for US$1800.
    • 1983: Radio Shack introduces the TRS-80 Pocket Computer, Model PC-4, replacing the PC-1, for US$70.
    • 1983: Tandy releases the TRS-80 Model 2000, which uses the Intel 80186 microprocessor.
    • 1983: Radio Shack unveils the TRS-80 Model 12 at the CP/M '83 Show. Price is US$3200.
    • 1985: March - Radio Shack introduces the Tandy 6000 multiuser system. It features Z80A and 68000 processors, 512 KB RAM, 80x24 text, graphics, 1.2-MB 8-inch disk, optional 15 MB hard drive, TRS-DOS, or XENIX 3.0. It supports up to 9 users.
      Source: Chronology of Events in the History of Microcomputers

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