Editing Apple DOS (section)

===Integer BASIC and Applesoft BASIC support===
The original Apple II included BASIC interpreter in ROM known originally as ''Apple BASIC'' and later as ''[[Integer BASIC]]''. Variables in this language can only handle integer numbers ranging from −32,768 to +32,767 ([[16-bit]] binary values); [[floating point]] numbers are not supported. Apple commissioned [[Microsoft]] to develop [[Applesoft BASIC]],<ref name="Applesoft">{{cite web|url=http://apple2history.org/history/ah16.html#05|title=Apple II History Chapter 16|author=Steven Weyhrich|access-date=2009-01-26|archive-url=https://web.archive.org/web/20090129131828/http://apple2history.org/history/ah16.html#05|archive-date=29 January 2009|url-status=dead}}</ref> capable of handling floating-point numbers. Applesoft BASIC cannot run Integer BASIC programs, causing some users to resist upgrading to it.

DOS 3.3 was released when Applesoft BASIC was standard in ROM on the Apple II Plus, so Apple designed it to support switching back and forth between the two BASIC interpreters. Integer BASIC is loaded into RAM on the language card of Apple IIs (if present) and by typing {{code|FP}} or {{code|INT}} from BASIC, the user can switch between either version.