Let's
pay Hommage to the Big Daddy of all PCs !
The
revolutionary machine which is responsible
for all this mad techno craze has been born 30 years ago !
The
Xerox Alto Computer
In 1972, Xerox Corporation decided to produce
a personal computer to be used for research. The result was the
birth of the Alto computer in 1973 , whose name comes
from the Xerox Palo Alto Research Center where it was developed.
The
Alto was the result of a joint effort by Ed McCreight, Chuck
Thacker, Butler Lampson, Bob Sproull, and Dave Boggs, who were attempting
to make a device that was small enough to fit in an office comfortably,
but powerful enough to support a reliable, high-quality operating
system and graphics display.
Their
goal was to provide each user with a personal computing facility
capable of meeting all individual needs and a communications facility
that would allow users to share information easily.
In 1978, Xerox donated a total of fifty Altos to Stanford,
Carnegie-Mellon, and MIT (Massachusetts Institute of Technology).
These machines were quickly assimilated into the research community
and rapidly became the standard against which other personal computers
were judged.
The
Alto consists of four major parts: the graphics display,
the keyboard, the graphics mouse, and the disk storage/processor
box.
Each
Alto is housed in a beautifully formed, textured beige metal
cabinet that hints at its $32,000 price tag (1979US money). With
the exception of the disk storage/processor box, everything is designed
to sit on a desk or tabletop.
The
concept of using a visual interface originated in the mid 1970s
at the Xerox Palo Alto Research Center (PARC) where a graphical
interface was developed for the Xerox Star computer system introduced
in April 1981.
The Xerox Star did not experience any commercial success, but its
ideas were copied by Apple Computer, first in the innovative Lisa
in 1983 and then in the Apple Macintosh introduced in January 1984.
The Mac used the Motorola 68000 32-bit CPU running its own proprietary
operating system. The primary new application that made the
Mac popular was graphical desktop publishing.
Xerox
Alto CPU PerformanceBCPL:
5-10 uSec for a simple expression
Nova Asm: 1-2uSec / instruction
Microcode: 170 nSec / micro instruction
Alto
Hardware Generations
The
Original Alto
The original machine, built in Palo Alto by PARC
The easiest way to tell if an Alto is the original or Alto 2 is
that the original Alto has a small toggle switch on the faceplate
of the CPU box. The backplane of an orignal Alto is horizontal in
the chassis. The cards in an Alto 2 mount vertically.
The
Alto II
Manufactured by Xerox, El Segundo. The second generation Alto has
a number of design changes that made it easier to manufacture, like
a PC board backplane instead of a wirewrapped one that the original
machine had.
The
Alto II XM
Added bank-switch logic to address up to 256k words of memory, and
could have 2 or 3k of writable microcode control store
Alto
Interface Cards
Trident
Disc Interface
Orbit
Laser Printer Interface
Raven
Laser Printer Interface
RS232
Serial Interface
1822 Arpanet
IMP Interface Patents
Programming
Languages on the Alto
Assembly
Language and User-written microcode
There were some low-level utilities that were written in assembly
language for the Alto. The base instruction set is very similar
to the Data General Nova, with extentions for things like BitBLT
and for executing user written microcode. Henry Baker and Clinton
Parker wrote a compiler which would convert SPL to Alto Microcode.
More details on the low level aspects of the Alto can be found in
my Alto Archive.
BCPL
An algol-like language similar to C (it actually looks a lot like
Tiny-C) which was used for system programming on the Alto. The Alto
Executive is written in BCPL, as are some of the utility programs.
Later application and system programming was done in Mesa.
Mesa
A strongly typed high level language, which was developed as the
main development language for the commercialization of the PARC
personal computer. Early software development for the D machines
was done on the Alto using the Mesa Development Environment (later
called XDE).
Smalltalk
The Learning Research Group at Xerox PARC developed their own programming
language, which was similar to SIMULA called Smalltalk. The famous
visit by Steve Jobs and other members of the Apple Lisa team saw
a Smalltalk demo in LRG.
Applications
(The ones documented in the Alto Users Handbook)
Bravo
WYSIWYG text editor
BravoX
Mesa implementation of Bravo, an ancestor of Microsoft Word
Laurel
Electronic mail program
Neptune
Disk file manipulation program, sort of like sweep.
Works like the Font DA mover program on a Macintosh.
Press
Document printing program
Sil
Drawing program Games
Most of the games were written at CMU or the University of Rochester.
Clint Parker, one of the legendary Alto microcoders at the U of
Rochester, wrote a bunch of them (like the pinball program..).
Clint is an elusive character.. I've been trying to contact him
by mail and phone for a couple of years now without success.
Astro-roids
Chess
Galaxians
Mazewar
Rinky
Dink (Clint Parker's pinball program)
Space
War
Trek
Missile
Command (Written by Avie Tevanian)
Server
Applications
IFS
The "Interim File Server" network file service. Could act as a file
server and boot server for Altos on a 3mb Ethernet.
Juniper
Laurel
(mail server)
Spruce
A laser printer server
