TRS-80 Model III

The TRS-80 Model III, released in July 1980, was the direct successor to the Model I, offering an all-in-one design that integrated the monitor, keyboard, and floppy drives into a single unit. It retained full compatibility with Model I software but improved reliability by eliminating the external cabling issues that plagued its predecessor. Featuring a Z80 CPU, up to 48KB of RAM, an 80-column text display, and built-in sound (finally!), the Model III became a fixture in schools and small businesses. It marked a transition toward more self-contained systems just before the IBM PC era began.

Notable Features

• Fully integrated design – no more expansion cables or external monitor
• Improved keyboard with better tactile feel and layout
• CP/M capable with aftermarket modifications
• Supported more disk formats and RAM configurations than Model I
• Optional lowercase display and improved character set

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Historical Significance

• Marked the professional maturation of Tandy’s home/business line
• Widely adopted in educational institutions and offices
• Maintained strong backward compatibility with Model I software
• Considered a reliable, affordable competitor to Apple II and early CP/M machines
• Provided the foundation for the TRS-80 Model 4

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Collector's Notes

• Rarity: Moderate – plenty produced, but fewer fully working units survive today
• Desirability: High among vintage 8-bit enthusiasts and Tandy collectors
• Common Issues:
  • CRT degradation or flicker
  • Cassette circuitry failure
  • Disk controller chip faults
  • Aging PSU capacitors
• Display Tips: Showcase running VisiCalc, Sargon Chess, or a classic TRS-80 Adventure with a Model 100 printer alongside

Specifications

Technical Information
Name	TRS-80 Model III
Manufacturer	Tandy
Launched	Tuesday, July 1, 1980
Discontinued	1983
Launch Price	$699 USD
Country	United States
CPU	Zilog Z80A @ 2.03 MHz
Units Sold	~200,000
Power	Internal 120V PSU (U.S. models)
Operating System	TRSDOS 1.3, LDOS, CP/M (with expansion)
Expansion	RS-232C serial, Centronics parallel, optional hard disk via expansion
Storage	Cassette interface (500 baud), up to 2 × 5.25" floppy drives
Keyboard	Full-stroke 53-key QWERTY keyboard with numeric keypad
Sound	Internal speaker for basic beeps and tones
Graphics	Semigraphics via custom character sets
Display	80×24 or 64×16 text (12" monochrome CRT)
ROM	14KB (Monitor, Level II BASIC, keyboard handling)
RAM	16KB or 48KB configurations