docs/13-differences.md

# 13. Differences from BASIC 7.0

If you already write Commodore BASIC, this is the chapter to read first. Everything
here is deliberate, and everything is recorded in the repository's `TODO.md` with the
reasoning — this is the short version.

## The language

### Variables carry a type suffix, and the suffixes differ
Write the usage guide as thirteen chapters in docs/ Organised the way the C128 Programmer's Reference Guide is: the language first, then each hardware area, then the reference sections. One markdown file per chapter. The verb and function references are generated from the interpreter's own dispatch table, with an assertion that every row is described, so they cannot drift out of step with what the program accepts. 98 verbs and 30 functions. Every example was run before it was written down, which caught three claims that were wrong: a whole FOR loop on one line prints nothing rather than looping once, MID and INSTR count from zero where a C128 counts from one, and a multi-line DEF returns a value the caller has to assign away. Chapter 13 is the list a BASIC 7.0 programmer needs -- roughly sixty documented differences, including the two known FOR defects and the fact that drawing does not survive a frame. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Co-Authored-By: Andrew Kesterson <andrew@aklabs.net> 2026-07-31 21:50:50 -04:00			`# 13. Differences from BASIC 7.0`

			`If you already write Commodore BASIC, this is the chapter to read first. Everything`
			here is deliberate, and everything is recorded in the repository's `TODO.md` with the
			`reasoning — this is the short version.`

			`## The language`

			`### Variables carry a type suffix, and the suffixes differ`