TRS-80 Model 4P

The TRS-80 Model 4P, introduced in September 1983, was a portable version of the TRS-80 Model 4. Housed in a self-contained luggable case with a 9-inch green-screen CRT, detachable keyboard, and dual 5.25" floppy drives, it retained full compatibility with the Model III and Model 4 software. While it lacked internal expansion slots and CP/M compatibility out of the box, the 4P offered unprecedented portability for a business-class 8-bit computer. It found success in field offices, classrooms, and tech support roles where mobility mattered more than expandability.

Notable Features

• Compact, integrated “luggable” case with carrying handle
• Dual floppy drives allowed full OS booting and data storage
• Detachable keyboard clipped to front for travel
• Display and keyboard powered from internal PSU – no separate monitor required
• Could be modified for CP/M and RAM upgrades by experienced users

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Historical Significance

• One of the earliest true portable business computers
• Aimed at mobile professionals, education, and field support techs
• Often used in sales, data collection, and technical service departments
• Less expandable than desktop Model 4, but far more mobile
• Paved the way for later luggable and portable PCs, including the Tandy 2000 and Tandy 6000 series

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Collector's Notes

• Rarity: Moderate – decent numbers sold but full-function units are less common
• Desirability: High for vintage portable collectors and Z80 hobbyists
• Common Issues:
  • CRT dimming or flicker
  • Floppy belt degradation
  • ROM chip failures on early units
• Display Tips: Looks brilliant booting TRSDOS from Drive 0 with bundled software like Scripsit or Profile

Specifications

Technical Information
Name	TRS-80 Model 4P
Manufacturer	Tandy
Launched	Thursday, September 1, 1983
Discontinued	1985
Launch Price	$1,795 USD
Country	United States
CPU	Zilog Z80A @ 4 MHz
Units Sold	~100,000
Power	Internal PSU, 120V (U.S. standard), no battery support
Operating System	TRSDOS 6, LDOS, Montezuma Micro CP/M (with ROM mod)
Expansion	Limited – no internal expansion bus; ports for serial and printer
Storage	Dual 5.25" single-sided floppy drives (180KB–360KB)
Keyboard	Full-travel detachable keyboard with 12 function keys and numeric pad
Sound	Internal beeper
Graphics	No bitmap graphics (character-based display)
Display	9" green phosphor CRT, 80×24 text display
ROM	24KB (bootloader and keyboard handler)
RAM	64KB standard (upgradable to 128KB unofficially)