TRS-80 Model 4

Launched in April 1983, the TRS-80 Model 4 was the final and most powerful system in Tandy’s Model I/III/4 lineage. It featured a Z80A processor at 4 MHz, up to 128KB of RAM, CP/M compatibility, and a new 80×24 display with lowercase characters standard. The all-in-one form factor remained, with support for dual 5.25" floppy drives and optional hard disk models. It was marketed to both business and educational users, offering significant improvements in speed, software support, and usability — while retaining compatibility with the huge TRS-80 Model III library.

Notable Features

• CP/M 2.2 compatibility out of the box (with 64K mode)
• Lowercase support as standard – no more aftermarket mods
• Improved keyboard, faster disk access, better screen contrast
• Dual drive configurations common, but also shipped with hard drive (Model 4D)
• Model 4P was a portable version with a built-in screen and carrying handle

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Historical Significance

• The final refinement of the original TRS-80 family
• Used widely in schools, accounting, and data entry applications
• Solid CP/M compatibility made it a cost-effective business machine
• Later versions (like the Model 4D) added 720KB drives and expanded OS support
• Largely eclipsed by IBM PC compatibles by the late 1980s, but had strong aftermarket life

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Collector's Notes

• Rarity: Moderate – many sold, but working drives and CRTs becoming scarce
• Desirability: High for Z80, CP/M, and Tandy collectors
• Common Issues:
  • Floppy drive failure due to alignment or aging belts
  • Screen dimming or CRT flicker
  • PSU capacitor aging and keyboard membrane wear
• Display Tips: Best shown with a working TRSDOS or CP/M boot disk and a classic program like WordStar or VisiCalc

Specifications

Technical Information
Name	TRS-80 Model 4
Manufacturer	Tandy
Launched	Friday, April 1, 1983
Discontinued	1987
Launch Price	$1,999 USD (dual-floppy model)
Country	United States
CPU	Zilog Z80A @ 4 MHz
Units Sold	~250,000–300,000 units
Power	Internal PSU (~150W typical draw)
Operating System	TRSDOS 6.2, LDOS, CP/M 2.2, NewDOS/80
Expansion	RS-232 serial port, Centronics parallel port, internal expansion bus
Storage	Dual 5.25" floppy drives (180–360KB each); hard drive optional
Keyboard	Full-travel 85-key keyboard with numeric keypad and function keys
Sound	Internal beeper (tone capable)
Graphics	No bitmapped graphics (character-based display only)
Display	80×24 monochrome CRT, lowercase included
ROM	24KB (Bootloader, keyboard handler, BASIC)
RAM	64KB standard, expandable to 128KB