View source for Lazer's Interactive Symbolic Assembler

{{for|the historical computer model from Apple|Apple Lisa}}
{{No footnotes|date=December 2020}}
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'''Lazer's Interactive Symbolic Assembler''' ('''Lisa''') is an interactive [[MOS Technology 6502|6502]] [[assembler (computing)|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 [[megahertz|MHz]] computer, a speed achieved due to the editor's pre-parsing of source code into tokens. This process makes the source files smaller on disk and in memory in addition to making assembly faster.
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 [[transistor-transistor logic|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 [[subroutine]]s 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 [[WDC 65816/65802|65816]] CPU.
== References ==
* Ward Douglas Maurer, ''APPLE assembly language with Lazerware software'', Computer Science Press, 1984, {{ISBN|0-914894-82-X}}
== External links ==
* [http://www.appleoldies.ca/anix/index.htm#lisa Lisa history and PD download] at Apple Oldies by Bill Buckels
* [https://www.scribd.com/doc/2429815/Using-6502-Assembly-Language-by-Randy-Hyde How to Program the Apple II Using 6502 Assembly Language, with an Introduction to Sweet-16, 2nd Printing, December 1982, by Randy Hyde]
[[Category:Assemblers]]
[[Category:Apple II software]]
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