ITT 2020

They never supplied the upgraded 140 kB single-sided, double-density drive supporting 16 sectors under DOS 3.3.

Only programs written specifically for the ITT 2020 could make proper use of the Hi-res graphics, with horizontal co-ordinates of up to 359, rather than the 279 maximum of the Apple II ITT eventually released a technical note with an assembly language program that allowed users to load and save hi-res images.

This made it necessary to modify the graphics routines in Apple's Applesoft BASIC interpreter in ROM (product 341-0021 to 341-0025).

This is achieved as follows: The bitmap graphics compatibility with the Apple II could be improved by installing a third-party Hires conversion board.

When enabled, this board removes the video artifacts caused by programs ignoring the 9th bit.

This significantly improves compatibility with software intended for the original Apple II manipulating graphics memory directly.