Extended Color BASIC

Extended Color BASIC is an update to the Color BASIC interpreter for the Radio Shack/Tandy TRS-80 Color Computer series, and is the default BASIC interpreter for the Color Computer 2. It was developed by Microsoft (designed by Bill Gates) and first appeared in 1984.

Overview

Extended Color BASIC resides on additional ROM beyond the 8 KB of standard Color BASIC, requiring 16 KB of memory total. It adds graphics and sound commands to the core Color BASIC language. While it was an optional upgrade for the original Color Computer 1 (available via a ROM pack or cartridge), it was built into the ROM of the Color Computer 2 as the default interpreter.

Features Added Over Color BASIC

Extended Color BASIC introduced several new commands and capabilities not present in standard Color BASIC:

• Graphics commands: PMODE (set graphics screen mode), PCLS (clear graphics screen), PSET (set a pixel), PRESET (reset a pixel), LINE (draw lines), CIRCLE (draw circles), PAINT (fill an area with color), DRAW (vector graphics using a string-based drawing language)
• Sound commands: PLAY (play music using a string-based note language), SOUND (generate tones)
• Color commands: COLOR (set foreground/background colors for text), SCREEN (switch between text and graphics modes)
• Additional functions: POINT (get color of a pixel), GET/PUT (save and restore rectangular screen regions for animation)

Variants

• Extended Color BASIC (ECB) — The standard graphics and sound extension for the Color Computer 1 and 2.
• Enhanced Color BASIC — A further updated version for the Color Computer 3 (CoCo 3), adding support for higher-resolution graphics modes (640×192 and 320×192 with up to 16 colors), 80-column text, and additional commands.
• Disk Extended Color BASIC (DECB) — A version containing routines for floppy disk management, loaded when a disk controller cartridge is plugged in. This adds commands such as DIR, LOAD, SAVE, KILL, OPEN for disk files, DRIVE, and DSKINI.

Platform

Extended Color BASIC runs on the TRS-80 Color Computer 2 and Color Computer 3. The Color Computer BASIC implementations are distinct from the BASIC interpreters found on other TRS-80 machines (Levels I, II, and III). Modified subsets of Color BASIC also appear on several Radio Shack PC series pocket computers of the era.

References

• Getting Started With Extended Color BASIC, 1984, Tandy Corporation. Publication #811013700A
• Color Computer 3 Extended Basic, 1986, Tandy Corporation. Publication #81101910A
• Inman, Don (1982). TRS-80 Color Computer Graphics. Reston Publishing Company, Inc.
• Wikipedia: Color BASIC, Extended Color BASIC