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Integer BASIC programming language

Integer BASIC was the BASIC interpreter that was included in the ROM of the Apple II computer when it was released in 1977, and as such was the first version of BASIC that was used by the first wave of home computer users and programmers. It was written by Steve Wozniak. Thousands of programs were written in Integer BASIC for commercial and private use.

The most frequently cited flaw of Integer BASIC was, as one might expect from the name, that its variables were all integers and it was very difficult to write a program that could do calculations using floating point numbers. It was therefore very difficult to write financial or math programs. Apple Computer licensed a more full-featured version of BASIC from Microsoft, introduced some tweaks, named it Applesoft BASIC, and included it in the ROMs of the Apple II Plus computer, which was released in 1979. Integer BASIC was relegated to a file on a floppy disk that Apple II Plus users could load into a RAM card for backward compatibility, if needed. Applesoft BASIC was included in the ROMs of all subsequent Apple II models, and became the foundation of probably hundreds of thousands of programs.

The Integer BASIC ROMs also included a "mini-assembler" that let programmers type assembly language programs, line by line, which were entered into memory. This was of course far easier than looking up the corresponding opcodes in machine language and typing those in. These ROMs also included an interpreter for a simple 16-bit assembly language, called Sweet16, which was very simple, compact and worthy of study. These two features, some cassette tape I/O routines, and a few seldom-used math routines were removed in the transition from the Integer BASIC ROMs to the Apple II Plus ROMs, in order to accommodate the larger size of the Applesoft BASIC interpreter.