TRS-80 Model III

26-1061 · 26-1062 · 26-1063 · 26-1066 · 1980–1984 · desktop

Specifications

Cpu: Zilog Z80A, 2.03 MHz
Ram: max: 48 KB on-board (no separate expansion box required, unlike the Model I) · base: 4 KB or 16 KB depending on configuration
Ports: Cassette in/out (built-in deck) · Expansion bus connector · RS-232 serial (on expanded/disk models) · Parallel printer port · Built-in monitor (integrated, not a separate port)
Display: Built-in monochrome monitor, 64x16 text (32x16 in wide mode), block graphics
Storage: base: Cassette tape via a built-in cassette deck (no internal storage) · options: One or two internal 5.25" floppy disk drives (single density, ~180 KB per disk), factory-installed
Os Support: latest: TRSDOS 1.3, with LDOS and Newdos/80 as popular third-party alternatives · shipped: Level I BASIC in ROM on cassette-only units; Model III Level II (Microsoft) BASIC in ROM on most configurations
Release Price: $699 (Level I, 4 KB, cassette only) to around $2,495 (16 KB, two disk drives)

Variants

Storage

4KB RAMcassette-only base configuration, 1980

16KB RAMsingle disk drive configuration

48KB RAMmax RAM, two disk drive configuration

Upgrade paths

RAM

48 KB on the motherboard · Unlike the Model I, RAM expansion is on-board: no external Expansion Interface box is needed, just chip swaps and jumper changes.

~$100 for a RAM upgrade kit at the time

MODERATE

storage

Two internal 5.25" floppy drives, or up to two external drives via the expansion bus on some configurations · Drives mount inside the case next to the built-in monitor, a big convenience win over the Model I's separate Expansion Interface.

~$500 per internal drive kit at the time

MODERATE

other

Third-party 300 baud modem and RS-232 boards for telecommunications · Popular for BBS use once disk-based DOS variants like LDOS were running.

~$200 for a modem card

MODERATE