Editing Microsoft BASIC (section)

===TRS-80 Level II/III BASIC===
The TRS-80 computer was offered initially with an adaption of Li-Chen Wang's [[Tiny BASIC]] ([[Level I BASIC]]); within a few months this was replaced by a port of BASIC-80 which incorporated some of Level I BASIC's command set, particularly the commands for setting graphics characters. Level II BASIC contained some of the features of Extended BASIC, although due to the need to include Level I commands such as <code>SET</code> and <code>PSET</code>, other features such as descriptive error messages still had to be left out; these were subsequently added into TRS-80 Disk BASIC.

The TRS-80 Model 4 had a newer disk-based BASIC that utilized the BASIC-80 5.x core, which included support for 40-character variable names. Thus the ability to crunch program lines (without spaces between keywords and arguments) was no longer possible as it had been in Level II. It was no longer necessary to reserve string space. New features included user defined functions (<code>DEF FN</code>) and access to TRSDOS 6 system functions via a <code>SYSTEM</code> keyword. A modified version published later by OS provider Logical Systems, in the LS-DOS Version 6.3 update, added single-letter access to BASIC control functions (like <code>LIST</code> and <code>EDIT</code>) and direct access to LS-DOS supervisor calls. The program edit environment was still line-oriented. The facility available in Level II to sort arrays (<code>CMD"O"</code>) was not available; programmers and users had to devise their own workarounds.