Lazer's Interactive Symbolic Assembler (Lisa) is an interactive 6502 assembler for Apple II computers written by Randall Hyde in the late 1970s.

The latest version of Lisa for 8-bit code is V3.2. Lisa includes an integrated editor with syntax checking. Lisa can assemble up to 30,000 lines of code in a minute on a 1 MHz computer, a speed achieved due to the editor's pre-parsing of the source code.

Lisa, before v.3, was able to assemble SWEET16 codes, a virtual 16-bit processor implemented as part of the Integer BASIC. However, the Apple II's Integer BASIC ROMs were replaced by Applesoft BASIC ROMs since the Apple II+, and the latter didn't contain the SWEET16 interpreter code.

The assembler also features "Randy's Hi-res Routines", a set of 2D computer graphics commands. Apple II's hi-res display pages (Hi-Res 1: 280 × 160 and Hi-Res 2: 280 × 192) were implemented by Steve Wozniak using two TTL chips. Therefore, a software programmer has to deal with the discontinuous addressing of screen pixels (a full screen is split into three parts horizontally) and each pixel's coloring properties (each pixel uses 1-bit, its color is determined by its place in a byte and its neighboring pixel). These ready-made subroutines were created to help programmers.

Lisa has a built-in disassembler.

An enhanced version of Lisa, called Lisa 8/16, was developed for the Apple IIgs It has a mouse-based UI and support for the 65816 CPU.

All versions of LISA use a custom interface editor that stores source code in a tokenized form, which makes the source files smaller on disk and in memory.

References

  • Ward Douglas Maurer, APPLE assembly language with Lazerware software, Computer Science Press, 1984, ISBN 0-914894-82-X


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