Lisa assembler
Encyclopedia
Lazer's Interactive Symbolic Assembler (Lisa) is an interactive MOS 6502
assembler for Apple II computers written by Randall Hyde
in the late 1970s.
The latest version of Lisa is V3.2. Syntax mistakes can be reported immediately in the edit mode. Lisa can assemble about 30,000 lines of code in a minute on a 1 MHz computer.
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 that bit's place in a byte and its neighboring pixel). These ready-made subroutine
s were created to help programmers.
Lisa has a built-in disassembler
.
MOS Technology 6502
The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. When it was introduced, it was the least expensive full-featured microprocessor on the market by a considerable margin, costing less than one-sixth the price of...
assembler for Apple II computers written by Randall Hyde
Randall Hyde
Randall Hyde is best known as the author of , a popular book on assembly language programming. He created the Lisa assembler in the late 1970s and developed the High Level Assembly language....
in the late 1970s.
The latest version of Lisa is V3.2. Syntax mistakes can be reported immediately in the edit mode. Lisa can assemble about 30,000 lines of code in a minute on a 1 MHz computer.
Lisa, before v.3, was able to assemble SWEET16
SWEET16
SWEET16 is an interpreted "byte-code" language invented by Steve Wozniak and implemented as part of the Integer BASIC ROM in the Apple II series of computers...
codes, a virtual 16-bit
16-bit
-16-bit architecture:The HP BPC, introduced in 1975, was the world's first 16-bit microprocessor. Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816. The Intel 8088 was program-compatible with the Intel 8086, and was 16-bit in that its registers were 16...
processor implemented as part of the Integer BASIC
Integer BASIC
Integer BASIC, written by Steve Wozniak, was the BASIC interpreter of the Apple I and original Apple II computers. Originally available on cassette, then included in ROM on the original Apple II computer at release in 1977, it was the first version of BASIC used by many early home computer owners...
. 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
2D computer graphics
2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...
commands. Apple II's hi-res display pages (Hi-Res 1: 280 × 160 and Hi-Res 2: 280 × 192) were implemented by Steve Wozniak
Steve Wozniak
Stephen Gary "Woz" Wozniak is an American computer engineer and programmer who founded Apple Computer, Co. with Steve Jobs and Ronald Wayne...
using two TTL
Transistor-transistor logic
Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...
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 that bit's place in a byte and its neighboring pixel). These ready-made subroutine
Subroutine
In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
s were created to help programmers.
Lisa has a built-in disassembler
Disassembler
A disassembler is a computer program that translates machine language into assembly language—the inverse operation to that of an assembler. A disassembler differs from a decompiler, which targets a high-level language rather than an assembly language...
.