Once upon a time, 20 years ago to be precise, before there was an IBM PC there was a computer system affectionately called TrashDos. Actually, it wasn't all that bad. Based on the venerable Zilog Z-80 processor, which split from the Intel 4004 and 8008 parentage, it was one of the first commercially available systems for a new breed of computers that would come to be called PC's. (Supposedly, PC stands for Personal Computer, but many of us think it should really mean a Personal Confuser!)
Although limited in it's memory size and storage options and still a rather expensive machine, it had as it's main competition the little Apple 2 computer. Even then, the business world gravitated towards the more robust and flexible systems and away from the Apples, which were seen as a cute machine mostly applicable to the school environment. It was on the TRS-80 that DATOW Software was born.
The TRS-80 was from Tandy-Radio Shack and that is where the TRS designation came from. The 80 referred to the Z-80 processor which, if memory serves ran at a then blistering 2 MHz. By comparison, the Apple ran on a 6502 processor at a measly 1 MHz. It was also around that time that Cromemco offered for sale a kit to allow hackers (the meaning of THAT word has certainly changed over the years ) to build their own machines. The system was based on the S-100 bus for expansion, and the Operating System of choice then was called CP/M.
Several manufacturers came out with complete systems that ran the CP/M Operating System, since most people were not able to write the BIOS routines that were required to boot and run a home-brew system. Xerox produced the Xerox 820, which was a very impressive machine that would interface easily (ha!) with their MemoryWriter typewriters. It was also one of the first of what came to be called SBC's (Single Board Computers) that had Parallel and Serial ports as well as (tada!) Video! Up until then the only way to talk to these machines was to use a terminal over a serial link. This was slow and limited to character based displays of information, although some of us came up with some pretty clever ways to display graphics on terminals. Of course, Apple also had real video output, but it was limited to 40 columns and not very well accepted by the world outside of the education market.