TRSDOS
Developed by: TandyLaunched: 1977
TRSDOS (Tandy Radio Shack Disk Operating System) is the operating system for the Tandy TRS-80 line of eight-bit Zilog Z80 microcomputers sold through Radio Shack from 1977 to 1991.
Tandy manuals recommended that it be pronounced triss-doss.
TRSDOS should not be confused with Tandy DOS, a version of MS-DOS licensed by Microsoft for Tandy's x86 line of personal computers (PCs).
Tandy Corporation's TRS-80 microcomputer did not have a disk drive or disk operating system at its release. The first version of TRSDOS, by Randy Cook, was so buggy that others wrote alternatives, including NewDOS and LDOS. After disputes with Cook over ownership of the source code, Tandy contracted Logical Systems, the developer of LDOS, to continue development of TRSDOS.
TRSDOS 6, distributed with the TRS-80 Model 4 in 1983, is identical to LDOS 6.00.
With the original TRS-80 Model I of 1977, TRSDOS was primarily a way to extend MBASIC (BASIC in ROM) with additional I/O commands that worked with disk files instead of the cassette tapes used by diskless Model I systems.
Later disk-equipped Model III computers used a completely different version of TRSDOS from Radio Shack, culminating in 1981 with TRSDOS Version 1.3.
Beginning in 1983, disk-equipped TRS-80 Model 4 computers used TRSDOS Version 6, which was a development of Logical Systems, Inc.'s LDOS Model III. The latter was updated in 1987 and released as LS-DOS 6.3.
Completely unrelated was a version of TRSDOS by Radio Shack for their 1979 TRS-80 Model II professional computer, also based on the Z80 and equipped with 8-inch disk drives. The later machines in this line, the Models 12, 16, and 6000, used the Z80 as an alternative CPU to their main Motorola 68000 chip and could run this version of TRSDOS for backward compatibility with older Z80 application software.
