TRSDOS (which stood for the Tandy Radio Shack Disk Operating System) was the operating system for the Tandy TRS-80 line of 8-bit Zilog Z80 microcomputers that were sold through Radio Shack through the late 1970s and early 1980s. Tandy's manuals recommended that it be pronounced triss-doss. TRSDOS should not be confused with Tandy DOS, a version of MS-DOS licensed from Microsoft for Tandy's x86 line of personal computers (PCs).
TRSDOS was primarily a way of extending the MBASIC (BASIC in ROM) with additional I/O (input/output) commands that worked with disk files rather than the cassette tapes that were used by most other TRS-80 systems.
TRSDOS supported up to four floppy (mini-diskette) drives which used 5ΒΌ-inch diskettes with a capacity of 89KB each (later 160KB). The drives were numbered 0 through 3 and the system diskettes (which contained the TRSDOS code and utilities) had to be in drive 0.
Commands
Some typical TRSDOS utilities:
Notes:
Since TRSDOS did not have the notion of redirection as UNIX/Linux and MS-DOS do, the APPEND command is somewhat different in concept than the UNIX or MS-DOS notion of appending via output redirection.
The CLOCK command displays a real-time clock in the upper corner of the display, almost like a DOS TSR (Terminate and Stay Resident); no exactly corresponding feature exists in MS-DOS or UNIX, though many programs provided similar features for DOS and the common UNIX shells could embed the time into their user-defined "prompt string".
Program invocation under TRSDOS, DOS and UNIX is done by filename; no explicit LOAD command is required for normal binary executables nor for text command files (batch files in DOS and shell scripts in UNIX/Linux). The LOAD command under TRSDOS would load a binary program into memory, but would not execute it; neither DOS nor UNIX has an equivalent.
Under DOS and UNIX printing a file can be done with redirection; under UNIX it is normally done by spooling the file to the "line printer" (using the lpr command) because UNIX is conventionally a multi-user system.
ATTRIB, PROT, and the chmod UNIX command are all somewhat different in their semantics. UNIX/Linux is multi-user and each user can control read, write, and execute permissions on his or her own files and directories. MS-DOS is single user and the file attributes for "read-only," "hidden," and "system" are advisory in nature. TRSDOS was single user but supported some sort of on-disk password protection for specific files.
The AUTO command set an automatic command to be executed on TRSDOS boot; under MS-DOS the special, reserved file named AUTOEXEC.BAT contained a list of such commands. On UNIX a set of one or more rc files under /etc/ are a set of boot time "run commands" and special "dot files" in a user's home directory are run for each time that a given user logs into the system. UNIX supports many other "dotfiles" for many of its commands which are akin to the Macintosh "preferences" folder contents.
TRSDOS (version II) was notable for the inclusion of noise words, similar to the 1959 COBOL specification. These made commands more English-like. For example, the following commands functioned identically:
COPY filea fileb
COPY filea TO fileb
Many versions supported a simple password security for files and programs, with separate Read/Execute and full access capabilities. ex: filename/ext.password:drive#
Although MS-DOS owes its heritage most closely to CP/M and thence to TOPS-10, many of the file manipulation commands are very similar to those of TRSDOS. By comparison the CP/M command for copying files was called pip (both a pun on the Pip printers, a chain of copy centers in that era, and an acronym standing for "Peripheral Interchange Program").
May 8, 1979 - Radio Shack releases TRSDOS 2.3
May 1, 1981 - Radio Shack releases Model III TRSDOS 1.3
