Editing Applesoft BASIC (section)

===Limitations===
Through several early models of the Apple II, Applesoft BASIC did not support the use of [[lowercase]] letters in programs, except in strings. <code>PRINT</code> is a valid command but <code>print</code> and <code>Print</code> result in a syntax error.

Applesoft lacks several commands and functions common to most of the non-6502 Microsoft BASIC interpreters, such as:
* <code>INSTR</code> (search for a substring in a string)
* <code>PRINT USING</code> (format numbers in printed output)
* <code>INKEY$</code> (check for a keypress without stopping the program; although a PEEK to location $C000 achieves this action)
* <code>LPRINT</code> (output to a printer instead of the screen)

Applesoft does not have commands for file or disk handling, other than to save and load programs via cassette tape. The Apple II disk operating system, known simply as DOS, augments the language to provide such abilities.

Only the first two letters of variables names are significant. For example, "LOW" and "LOSS" are treated as the same variable, and attempting to assign a value to "LOSS" overwrites any value assigned to "LOW". A programmer also has to avoid consecutive letters that are Applesoft commands or operations. The name "SCORE" for a variable is interpreted as containing the <code>OR</code> [[Boolean operator (computer programming)|Boolean operator]], rendered as <code>SC OR E</code>. "BACKGROUND" contains <code>GR</code>, the command to invoke the low-resolution graphics mode, and results in a syntax error.