Module igs 

Atari ST BBSes with IGS, Larry Mears’s “Instant Graphics and Sound” (version 2.19): VT-52 text and GEM VDI drawing on the ST’s own screen, 640x200 in four colors (medium resolution, where BBSes start), 320x200 in sixteen or 640x400 in two.

G# gets IGS’s attention; then a command letter, a > to chain another command after it (anything else ends the chain), and numbers, each ended by any one character that isn’t a digit. The parsing follows IG’s own source (IG217.C, and IG 2.19’s notes): numbers of up to four digits, _ and line breaks inside a number skipped, x, y, r, R, +n, -n and !n for loops and random values.

Everything, text included, is drawn into a bitmap of color registers, which the front end shows like RIPscrip’s graphics. Fill patterns, hatches, line styles and marker shapes are the VDI’s, as EmuTOS (GPL 2 or later) defines them. Sound (the sound chip’s effects, chip music and MIDI) is read past and not played.

Structs

Igs

Enums

Res

Constants

COLS

The text screen the front end lays out (the bitmap is stretched over it).

MAX_HEIGHT

MAX_WIDTH

ROWS