Tandy TRS-80 Model 4D

The Tandy TRS-80 Model 4D was the final desktop version of the original TRS-80 Z80 family. It updated the Model 4 with two half-height double-sided floppy drives, a green-screen display and Tandy rather than Radio Shack branding.

The 4D kept the mature TRSDOS/LS-DOS environment available into the later 1980s while Tandy’s attention shifted to PC-compatible computers.

Notable Features

• Zilog Z80A at 4 MHz with 64KB standard; expandable to 128KB.
• The principal display was Built-in 12-inch green monochrome CRT; 80 x 24 text.
• Storage support consisted of Two built-in double-sided 360KB 5.25-inch floppy drives.

Historical Significance

• The 4D kept the mature TRSDOS/LS-DOS environment available into the later 1980s while Tandy’s attention shifted to PC-compatible computers.
• Radio Shack’s large retail network made demonstration, sales and support available well beyond specialist computer dealers.

Collector’s Notes

• Factory memory, drive configuration and regional badge should be checked because many surviving systems were upgraded.
• Original monitors, manuals, software, storage hardware and Radio Shack peripherals add historical context.

Specifications

Technical Information
Name	Tandy TRS-80 Model 4D
Manufacturer	Tandy
Launched	Tuesday, January 1, 1985
Discontinued	1991
Launch Price	$1199 USD
Country	United States
CPU	Zilog Z80A at 4 MHz
Units Sold
Operating System	TRSDOS 6 / LS-DOS; Model III compatibility mode
I/O	Printer, serial, cassette, expansion and external storage
Keyboard	Integrated keyboard with numeric keypad and function keys
Storage	Two built-in double-sided 360KB 5.25-inch floppy drives
Sound	Programmable beeper
Graphics	128 x 48 block graphics; optional high-resolution graphics
Display	Built-in 12-inch green monochrome CRT; 80 x 24 text
ROM	Model III compatibility and boot firmware
RAM	64KB standard; expandable to 128KB
CPU Speed	4 MHz