written by Matthew Reed

Level III BASIC advertisement

Level III BASIC advertisement from
H&E Computronics software catalog #3

Level III BASIC was an enhanced version of Level II BASIC for the TRS‑80 Model I. It was created by Microsoft, also the authors of Level II BASIC, but sold by GRT Corporation on cassette for $49.95. Level III BASIC was said to be the first consumer product from Microsoft, which had previously sold only to manufacturers.

Rather than sell Level III BASIC directly to consumers, Microsoft decided to release it through GRT Corporation in 1978. GRT Corporation, which stood for Great Records and Tapes, was a music company that had expanded into the software business. The GRT software division, named G2, was started by Vern Raburn and Level III BASIC was sold under the G2 label.

The Level III BASIC manual contains this surprising statement of authorship:

In 1975, Microsoft wrote Altair BASIC, the first BASIC interpreter for a microcomputer. Since then, Microsoft-written BASIC’s have become the virtual standard of the personal computing industry.

Microsoft has a reputation for quality, advanced programming techniques and efficiency that is surpassed by none. Level III BASIC was written by Microsoft president, Bill Gates.

Level III BASIC (not to be confused with Model III BASIC, the name Radio Shack later used for the Level II BASIC in the Model III) was a 5.2K cassette extension to Level II BASIC. It added commands that had been reserved for future use. Trying to use the reserved commands in Level II BASIC resulted in an ?L3 ERROR, meaning that Level III BASIC was required.

Level III BASIC added many different types of commands, including:

  • LINE to draw lines and boxes
  • GET@ and PUT@ to load and save portions of the screen into an array
  • LOAD and SAVE for improved cassette loading and saving
  • PRINT#-3 to print over the RS-232 port
  • INPUT# and LINE INPUT#, very interesting commands to provide length-restricted, timed user input

Another nice Level III BASIC feature was “Shift-Key Entries,” 26 shortcut keys invoked by pressing SHIFT plus a letter key. The command shortcuts, up to 15 characters long, could be changed by using the LSET command.

Level III BASIC offered many features that were also provided by Model I TRSDOS Disk BASIC. These included long error messages, hexadecimal and octal constants, and the elimination of keyboard bounce. Shared commands included NAME, LINE INPUT, INSTR, improved MID$, DEFN, DEFUSR, and TIME$.

These shared features were probably Level III BASIC’s biggest problem. Level III BASIC wasn’t compatible with Disk BASIC and there never was a disk version. They both served much the same purpose, yet the two systems weren’t compatible. The Level III cassette did include a special version designed to work under TRSDOS, but lacking any disk commands. Level III BASIC was also one of the few programs to be sold in an Exatron Stringy Floppy version.

On July 18, 1979, GRT Corporation declared bankruptcy and the G2 software division shut down. Bill Gates hired Vern Raburn to become president of Microsoft Consumer Products, a division created to sell software directly to consumers. Microsoft Consumer Products began selling Level III BASIC on December 1, 1979 and continued to sell it for several years.

Categories: Programming, Software


Terry Stewart says:

Yes, I used to use Level III BASIC when all I had was a Stringy Floppy pre: disk drives. It was a nice piece of software. From memory it WAS the stringy floppy version. All that remains with me from those days is the cassette version unfortunately.

Knut Roll-Lund says:

I bought Level III Basic with my video genie. I found level III to be nice but slow. I could calculate and poke graphics in regular basic faster. So I never used it much. Floppy made it completely obsolete and I was happy I never used it much. Some old L3 programs I made was on cassette and has been converted to cas but are not interesting…

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