TRS-DOS

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TRS-DOS (which stood for the Tandy Radio Shack - Disk Operating System) was the operating system for the Tandy TRS-80 line of 8-bit Z-80 micro-computers that were sold through Radio Shack through the late 1970s and early 1980s. Their own manuals recommended that it be pronounced triss-doss but the common derisive term referred to the platform as trash-eighties and thus this software was sometimes called trash-dos by loyalists of other computing platforms. TRS-DOS should not be confused with Tandy DOS a version of MS-DOS licensed from Microsoft for Tandy's x86 line of PC's.

TRS-DOS 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.

TRS-DOS supported up to four floppy (mini-diskette) drives which used 5 1/4" (five and one quarter inch) diskettes with a capacity of 160K (kilobytes) each. The drives were numbered 0 through 3 and the system diskettes (which contained the TRS-DOS code and utilities) had to be in drive 0.

Some typical TRS-DOS utilities (commands):

TRS-DOS Utilities with MS-DOS and UNIX translations
Utility	MS-DOS	UNIX/Linux
APPEND	TYPE file1 >> file2	cat file >> file2
ATTRIB	ATTRIB	chmod
AUTO	AUTOEXEC.BAT	~/.profile or ~/.login or /etc/rc*
BACKUP	DISKCOPY	tar, cpio, pax, (many others)
CLOCK	PROMPT $t *	in some shells: PS1="...\t..." *
COPY	COPY	cp
DIR	DIR	ls
FORMAT	FORMAT	mkfs
FREE	CHKDSK	df
GETDISK/GETTAPE	(???)	dd
KILL	DEL	rm
LIST	TYPE	cat
LOAD program	PROGRAM	program
PRINT	TYPE file >> PRN	lpr
PROT	ATTRIB	chmod
RENAME	REN or RENAME	mv

Notes:

Since TRS-DOS didn't 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 display 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 DOS and UNIX is done by filename; no explicit LOAD command is required for normal binary executables nor for text command files (.BAT files in DOS and shell scripts in UNIX/Linux).
Under DOS and UNIX printing a file can be done with redirection; under UNIX it's 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. TRS-DOS 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 TRS-DOS boot; under MSDOS 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.

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 TRS-DOS. 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 standing for "peripheral interface to peripheral").

CLOAD "FILENAME" is the format for loading tape programs on a TRS-80.