Radio Shack TRS-80 Model II
Announced:May 1979
Released:October 1979
Price:$3450 (32K RAM)
$3899 (64K RAM)
CPU:Zilog Z-80A, 4 MHz
RAM:32K, 64K
Ports:Two serial ports
One parallel port
Display:Built-in 12" monochrome monitor
40 X 24 or 80 X 24 text.
Storage:One 500K 8-inch built-in floppy drive.
External Expansion w/ 3 floppy bays.

The TRS-80 Model II microcomputer system, designed and manufactured by Radio Shack in Fort Worth, TX, was not intended to replace or obsolete the Model I, it was designed to take up where the Model I left off - a machine with increased capacity and speed in every respect, targeted directly at the small-business application market.

The Model II contains a single-sided full-height Shugart 8-inch floppy drive, which holds 500K bytes of data, compared to only 87K bytes on the 5-1/4 inch drives of the Model I.

From the Operators Manual:

Because of a special high-density recording technique, each diskette can contain 509,184 bytes of information, which is more than 5 times the capacity of a 5-1/4" diskette. (It would take a 70 wpm typist 24 hours of typing at speed to fill an 8" diskette.)

Also available is the matching computer desk and a high-performance line-printer. The desk includes a pull-out storage drawer, and the Disk Expansion Unit with space for three additional 8-inch floppy drives.

The cost:
  • Desk - $350
  • Computer - $3450 (32K RAM) - $3899 (64K RAM)
  • Disk Expansion - $1150 (1 disk drive) - $2350 (3 disk drives)
  • Line Printer III - $1999

  • Inside the computer cabinet, it's a different world. There is no motherboard, all of the logic circuitry are on circuit boards in a card-cage with a passive backplane.

    There are four cards installed:
  • Processor card with the 4 MHz Z-80A CPU,
  • Memory card with 64K RAM,
  • Floppy Disk Controller card,
  • Video Display card.

  • There are four open slots for future expansion. Other cards available include a hard disk controller, an arcnet network card, a graphics card, and a 6 MHz 68000 board set with extra memory (up to 512K) that can run XENIX.

    On the outside, there are two serial ports, one parallel port, and a connection for the external disk drives.

    Tandy had a great deal of software for the Model II, but there was not much support for the system from anyone other than Tandy.

    Related Links

  • TRS-80 Model II from Kees's Computer Home
  • TRS-80 Model II from Ira Goldklang's TRS-80 Revived Pages
  • TRS-80 Model II from
  • Robert P. VanNatta's comments on the TRS-80 Model II
  • Tim Mann's TRS-80 Pages

  • 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 for US$600.
    • 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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