Stephen Wozniak
The Making of an Engineer and
a Computer
I was lucky as a kid because my Mom
and Dad got me to do science fair
projects, tell jokes, and have fun. I
knew I'd get an electronics project for Christmas. I'd sneak down the night
before and open up the packages (then close them up again). It was sort of like
exploring a computer system without getting caught. In sixth grade my hero was Tom
Swift who used his resourcefulness with technology to do good. The kids on my block
wired house-to-house intercoms, helped by the local electronics store where we
hung out. We got someone to give us a ton of telephone wire and we just
walked down the block hammering it to the fences and jumping into people's
yards and burying it in the ground. When you're kids you don't understand that,
things are owned by others.
Mom gave me 35 cents a day for lunch. I didn't eat; I saved the money for a
walky-talky. But I got nailed. The school had a lottery and I spent all the money
on tickets. And I lost.
My father, an engineer, taught me how transistors work and got me
interested in computers by giving me IEEE reports to read. This way I learned the basics
of Boolean logic and built some adders/subtracters for science fair projects.
By eighth grade I talked a company into giving me a few hundred transistors and
diodes. I built some gates and figured out why they weren't working. It was a good
head start.
By the time I got to high school, I was real fast on the slide rule and
that helped me become the top math student. But when you're in math you don't take
electronics, because you're in the college curriculum. Electronics
was a shop course. Somehow a few people covered both. Neither the students
nor the teachers in high school knew what a computer was and vacuum tube
technology was still being taught. When I was a junior, a
teacher said "we now have a computer and you can use it." I said, "Great
... what an opportunity." It was a little board that could be wired to
create a relay. The teachers thought this was a computer!
Then, I had a teacher who recognized that I needed something beyond what the
school could provide. He had a couple of friends at Sylvania and arranged
for me to go down once a week to program computers. They gave me a FORTRAN manual and
I thought it was the neatest thing in the world. Then one day, I saw The
Small Computer Handbook on someone's desk. It described DEC's PDP-8. I read it
from cover to cover learning about binary arithmetic, how ands and ors work,
about registers, instruction sets, sequencing, and everything you needed to know
to build a minicomputer. Later, when the growth of minicomputers started exploding,
my favorite machine was Data General's
NOVA. I started to design my own versions of it. Sometimes it would take 20
pages to design a floating point add. Then I tried to make the design smaller and
smaller. Every time a company, like Fairchild, would come out with a new chip, I'd
go back and re-design the NOVA using that chip. I'd make the design better and
better using fewer chips. If I could have afforded building any of these machines,
I would have stopped designing and learning. The reward was in improving a design.
In 1968, I headed off to the University of Colorado where I signed up for a
computer class. This gave me the opportunity to sign up for computer time by using my
student number. I didn't understand that computer time was charged for. As
a kid I really didn't know about accounting principle sand I was still a kid. I was
put on probation for computer abuse. I ran some programs that just printed scrap
paper as fast as they could; others that ran every mathematical table that I could
find - powers of two, inverse powers of two, and so on. Eventually my factorials
would take more than a page and it would run 60 pages worth; that was what the CDC
machine could do in under the minute that I was allowed as a student. It
would punch out cards which I could submit again to make it start up exactly
where it had stopped. I used 60 pages for each of six sets of tabulations three times a
day for about a month. There were reams and reams stacked up in my dorm. I never
thought that my professor would think that I was trying to get him because
I was spending money that was unbudgeted.
That year I built my first video project, a device out of one transistor
and some old radio parts that jammed TVs. I didn't try it out in my dorm because they
knew me. I went to another dorm, sat in the TV room and started to jam the picture. A
friend, in on the gag, went up to the TV, hit it, and I unjammed the picture. Each
time I'd jam it, my friend would have to hit it harder and harder. Everyone
understands that
when an inanimate object doesn't work you just hit it. I discovered in that
age of peace-loving anti-war college students that you could turn any group
into animals just by jamming the TV set.
One time I jammed it and someone said
the TV repairman had been in and had
said it was the antenna. So he held the
antenna up in the air, and the set was
perfect, but only for a couple of minutes,
then it went bad again. The guy held it up
higher. Same scenario. When it went bad,
he stood up on a chair, and it worked, for
awhile. Upon his tiptoes it worked; down
on his heels it didn't work. On another
occasion they discovered if you touched
the set in a weird position -hand on set
and leg on the chair-it worked. He said,
"It's a grounding effect." And they watched
the last half hour of Mission Impossible
with a hand on the middle of the TV.
The computer class was very large. The
professor would lecture to a quarter of the
students and the rest would watch on TV
monitors in another room. I built the TV
jammer into a magic marker pen and took
it to class. The class started and I jammed
the TV. Three teaching assistants stood
up, looked us over and I was scared. Then,
before I paniced, someone picked up his
books and started to leave early. He was
near the worst jammed TV. As he got up
the TV started to go in and out, until as
he walked out the door it was perfect. I
learned that whatever prank you do, make
someone else get the credit.
My second year of college was in
Cupertino. They had an IBM 360. I took
some computer courses that gave me no
credit at all, but they were what I wanted
to take. I met a computer operator and I
found that as an insider he had keys and
passwords. We would go in late at night
and run programs. By sliding a piece of
paper over the official record on the
console printer, we prevented our jobs
from being recorded. One night the
manager of the center came in at about 2
AM and found me alone in the computer
room. I was scared because he didn't even
know me. I said, "Larry went out for the
pizza."
To pay for my third year of college, I went
to work for a mini-computer company. It
had a great machine with 64 terminals
that could run FORTRAN and other
programs. But the company was hit by the
recession and went under. It was
surprising for me to learn that people
could invest two million dollars in a
company and it couldn't make it.
In my spare time a friend and I built "The
Cream Soda Computer", because we drank
cream soda while we put it together from
spare parts given
to us by another company. The friend that
helped me build it, introduced me to
another friend, Steve Jobs. We were
introduced because we both liked pranks
and electronics.
In 1971, after a little stint on
unemployment insurance, I went to
Berkeley, one of a handful of colleges
offering computer science, for my third
year of college. I took a course on writing
assemblers and wanted to learn
computing, read every manual, try every
code, and learn every language. Getting
grades or going to classes was of
secondary importance. One time I signed
up for ten courses and only went to five.
Steve Jobs, a freer spirit, went off to Reed
College in Oregon, where he only attended
the courses that he wanted to, not the
ones that he was registered for. Reed was
also free and let him hang around for two
years.
One day at my parents house, I read an
article characterized as "fiction" about these weird phone phreaks
who drove around the country in vans with
racks of equipment in their buses,
plugging into communications networks.
The author, Captain Crunch,
philosophized that exploring the phone
system would improve it for Ma Bell. I fell
in love with this philosophy. I wanted to
explore a system and a computer and I
didn't care about free calls. Half way
through the article, I called Steve Jobs up
and started to read it to him. Suddenly I
realized there were too many details in
the article-frequencies of 700 hertz and
900 hertz. They gave too much
information. It's too real. These are not
things that a fiction writer can make up.
My source for material at the time was the
Stanford Linear Accelerator; I knew I
could always get in there on the weekend.
With those high end research types, the
door was never locked. Steve and I went to
the library and
started to research the phone system. We
discovered that the frequencies mentioned
in the article were correct. Now we knew
that we could build a box and make free
phone calls all over the world. We even
managed to meet the author of the article,
Captain Crunch. I was so pure about the
philosophy of the phone company as a
system, that I paid for my phone calls
home. Then, late at night, I'd call every
country in the world. I showed it off. I told
phone jokes. I sold blue boxes on the
campus. I just wondered how far I could
get. But I was still pure, I paid for
everything I should pay for-I was just using
unused wires. It was disappointing when I
found out that the phone phreaks were not
pure.
Blue Box, 1972 
Inspired by the "phone phreak" hero
Captain Crunch, Steve Jobs and Stephen
Wozniak built their own tone generators
to make free calls. Known as blue boxes,
they were sold in the dormitories of the
University of California at Berkeley where
Wozniak was an undergraduate. The
particular box shown here was
demonstrated to a packed roomful of
students performing the legendary
experiment of calling around the world to
a phone in the next room. The signals had
to travel over such a great distance that
there was sufficient delay for a person to
walk over to the receiving phone to hear
his own voice. Following this
demonstration, Richard Prelinger bought
the box for $120.
The box used a crystal oscillator and was
switched on or off simply by inserting or
removing the plug leading to the earpiece.
The early boxes were equipped with a
safety feature-a reed switch inside the
housing operated by a magnet taped onto
the outside of the box. Should the phone
phreak be apprehended, the magnet could
be removed quickly, whereupon the blue
box would generate distorted off-frequency
tones rendering it inoperable. "You tell
them it's just a music box", said Wozniak.
The taped-on magnet is visible on the
bottom right side of the box.
Gift of Richard Prelinger
After that year at Berkeley I had to take
another year off to work and earn enough
money to go back to college. I got a job as
an engineer at Hewlett Packard designing
scientific calculators, an incredibly good product that
bypassed slide rules. My career kept going
up. While it's widely reported that I'm a
college dropout, that's not true. It just took
ten years until I had enough money to
finish.
I started to get away from computers. The
blue boxes had been fun. Then I heard
about "Dial-a-Joke" and I started the first
one in the San Francisco area. In those
days you could not own your own answering
machine, you had to rent it from the phone
company. Two thousand calls a day came
into my machine to hear a Polish joke.
Then the Polish/American Congress
Incorporated in Chicago twice threatened
me with law suits. I said, "How about
Italian jokes?" They said, "Fine with us."
Twelve years later the organization gave me
their national heritage award.
One night after work, I walked into a
bowling alley and I saw the first Pong
game. It blew me away. I wanted one and
since I knew TV sets and digital logic, I
designed my own. Around that time, Steve
Jobs got a temporary job at Atari. He
introduced me to some of those people, but
I wouldn't leave such a good company as
HP for Atari. HP really cared about its
employees and I just didn't feel like
leaving, for any reason. On the side, Steve
and I got a job to design the game Breakout
for Nolan Bushnell at Atari.
Then, one day, I went to see my old friend
Captain Crunch who was in his basement
on a teletype. He said, "I'm playing chess
with someone at MIT." Then said, "Look I
can log into all these computers." He was
on the ARPANET. I said, "Wow, I've got to
do this." The only way that I could afford it
was to build a terminal. I designed a video
terminal because the cheapest input
output device was your own tv set. Later
Captain Crunch was to go to prison for
phone phreaking. The second time he got
caught the judge said that if he ever did
this again he would go to prison. He got
the same judge the third time.
I had been out of the computer area for a
while and I wasn't aware that the
microprocessor had been introduced. A
friend of mine, who had gone to MIT, called
me up and said there was club starting up
for people who had built terminals and
things. Since I had just built a terminal
and since I like to show off, I said, "Great,
I've got to go to this meeting and show off
my terminal." He didn't tell me it was a
microcomputer club because if he had, I
would have said, "I don't know anything."
And I wouldn't have
gone. I met a lot of interesting people there
who were all talking about the new Altair
Computer. Somehow everybody knew that
some day they were going to own there own
computer. I had decided back in high
school in the sixties that I was going to
own a personal computer - a 4K NOVA was
what I really wanted. At the time, it was
the cost of two Pintos and almost the cost
of a home. This was a big thing to think: to
have a computer instead of a home or a
car. Now I discovered that there were
people around who knew how to build
affordable computers. And, I got back into
the field by studying a microprocessor
instruction set, the inner workings of the
chip. I discovered a microprocessor was
just like a minicomputer.
Over the next year, the club grew to five
hundred members who met twice a week.
We all worked for companies with
mainframes-and submitted our decks of
cards through the window and the
computer priests would run the program.
We'd try to crash the system because it
wasn't ours. We were a group that had a
purpose: the revolution of home
computers. Byte Magazine started. In the
beginning most home computers were sold
as kits and you had to be a hobbyist who
knew how to use a soldering iron and not
be afraid to put one together. The members
of our club were not high level managers;
we ran around with holes in our jeans, and
were a technical community who wanted
their own computers. The club was based
on sharing. Lee Felsenstein conducted our
meetings. The first segment was called the
mapping period. People offered information,
material or discussed problems. For
example, one of the members would ask,
"Is there anyone here from AMI?" If no
hands went up, he'd say, "I've got some
chips to raffle off for the club." He gave the
first Pong chip fox your home Pong game to
members of the club before Atari got it.
Then, in the random access groups, people
matched offers and problems.
I still could not afford a computer so I started to think about building one for
myself. A new company called MOS Technology introduced a new
microprocessor, the 8-bit 6502 costing $400. It was the finest microprocessor yet
and they sold it over-the-counter at a show in San Francisco for $20-a very unique
marketing step. A lot of folks from the club bought one and that night at the
Homebrew Computer Club meeting it was a big topic.
A company called Sphere stopped by our club meeting with a 16-bit
minicomputer hooked up to a color monitor that spun a color clock around. To see a
computer doing color on a video screen was beyond our imaginations. It was shocking.
This was at the time that Microsoft BASIC was only available on paper tape for input
via Teletype terminals. The first two attempts at color for personal computing
came from the club: the Dazzler, built by Cromemco, and the Apple II computer.
Although I had a FORTRAN and ALGOL
background, I saw that BASIC was going to
be the language for personal computers.
Within two months I wrote a BASIC that
would run on the 6502. I wrote a simulator
in ALGOL to see that it would work. I had
to assemble the code by hand, because I
didn't have a computer to work on. Once it
was done, I put together what became
known as the Apple 1. I
worked hard and late to get it done before
January when I was getting married. In
late November 1975, I demonstrated the
Apple 1 computer running BASIC. All it
could do was a tab and a print.
I went to Hewlett Packard with the design
and the costs and suggested that they
manufacture and sell it for $800. My
manager was intrigued with a machine that
could run BASIC and have 4K of RAM that
would sell for about the same price as
HP's top-end calculators. He was
especially interested since HP's desk-top
machine sold for $5-8,000. He said no to
the project in the end. But this took
weeks.
One time when I was showing off the
computer at the club, Steve Jobs came
along and said, " Why don't we sell it?" I
was passing out a lot of schematics and
literature because a lot of people wanted
to build one. Steve said, "Let's just make
the PC board for $20 each and sell them at the
club for $40." We figured we'd have to sell
50 to get our money back and we didn't
think we could sell that many. Steve said,
"We might not sell 50, but at least we'll
have a company." Steve's motivation was
to be like Nolan Bushnell. I was telling
Steve about everything that
microprocessors would do one day, which
was everything that minis did. I bought a
microprocessor for $20, a keyboard for $60,
a few transformers for about $10 each, and
picked up the integrated circuits from the
lab stock at HP. The company has a
written rule that any engineer can take
chips from lab stock without cost for a
project of their own design if their
supervisor approves. The company feeds
that one learns by doing, and that the
lowest level of management can decide.
One day Steve called me up at HP and
said, "Guess what." "What?" "I
got an order for $50,000." That was the
biggest shock of the Apple experience.
Steve had gone down to the Byte Shop
where they bought Altairs as kits, wired
them in the backroom, and sold them as
personal computers. Steve discovered
that it would only cost $13 to insert all
the chips on our board. The Byte Shop
placed an order for 100 computers at $500
each and we had to purchase the parts.
To come up with the money, I sold my HP-
65 calculator for $500. However I knew we
were coming out with the HP-67 the next
month and my employee price would be
$37, so I didn't take much risk. I still had
my HP job as well. Steve went to the
component suppliers and by showing the
order asked for 30 days net credit. The
chips were stocked in a closet at the
company making the board. When the
chips came out of the closet the 30 days
started. When the pc boards came off the
line, they would be stuffed with the
chips and then put on the wave soldering
machine. In two days 25 boards were
complete and we drove over and took
them to Steve's garage. We'd plug in the
keyboard and the TV and some
transformers and test the boards with the
oscilloscopes to see if they would work.
On the weekends we would sit down with
the ones that didn't work, and usually
found the problem in bent pins. Then we
would deliver them to the local store and
get paid. It was a ten day cycle. It's
amazing what you can do when you have
one level of management.
The Apple 1 design had few chips and was
optimized for one board. The biggest
decision was memory; the first 4K
dynamic RAMS were about to come out.
One principle that Iliad was "the fewer
chips the better". After a discussion
about chip size and number of pins, I
decided that I would go for optimizing
board size. When the 4K
dynamic RAMS came out I could do in 4
chips what I used to do in 32. In 1975
several styles of 4K dynamic RAMS came
out; the first set were from AMI and the
second from Intel. The Apple 1 had the
right RAM, a 16 pin Intel chip that led to
a 16K RAM.
Apple 1, 1975
In designing the Apple 1, Wozniak
squeezed as many functions as he could
onto a single PC board. The upper two rows
of integrated circuits constitute the video
terminal he designed in 1974 to access
mainframes remotely; it contains its own
memory consisting of 7 1K dynamic shift
registers and displays characters in a 5 by
7 matrix, with 40 characters per line, 24
lines per page and automatic scrolling. It
interfaces to an ASCII encoded keyboard
which is plugged into the empty socket at
location B4. The video output and low
voltage AC power sockets are at the top
left corner. The lower two rows are the
computer, shown in schematic form on the
cover. The 6502 microprocessor is in the
white package on the bottom row towards
the left; the 16 chips on the right (A,B11-
18) are 4K dynamic RAM's; 2 PROM's,
containing the 256 byte resident system
monitor program, are at the bottom left
corner. The memory could be expanded to
65K via the edge connector on the right.
Gift of Dysan Corporation
After I had my legal release for the
machine and was selling Apple 1s, HP
had a project called Capricorn - doing
everything that I had just done. I went to
the new lab manager and I said I'd do
anything to work on the personal
computer and he turned me down.
Steve and I went to Atari and asked if
they would like it. They said, "No, the
home video market is going to be very
large." They were so friendly to us, that
they let us buy chips for the Apple 1 right
out of their warehouse. We went down to
Commodore and talked to Chuck Peddle
who was about to do the Pet Computer.
Steve thought we might get a few hundred
thousand dollars but they only offered us
employment. All in all about 200 Apple 1's
were sold out of the garage.
A few months later, I started to think
about color. I made sure that the Apple 1
worked at the right speed so that color
could be added. Things began to coalesce.
I realized that I could combine video
screen memory and processor memory
and save chips. The Apple II design
started to emerge. It would be twice as
fast, do twice as many things, and have
tons of memory. In the first days, I
designed the Apple II to work with both 4
and 16K RAMS (because the 16K chips
were still very expensive). There was an
issue of slots for extra cards. How much
do they matter? The only argument over
the Apple II design was that Steve Jobs
wanted two slots and I wanted eight
because I was a little leery about locking
into too little. So I sat down with Steve
and said, "OK, I don't want the company."
And we had eight slots. That was the end
of it.
I decided to write the Atari game Breakout
on a microprocessor, in BASIC not in
hardware. So I wrote some commands in
BASIC to put color dots on the screen and
to make sounds come over a little
speaker. It was shocking to me how much
you could do in software and still run so
much faster than hardware.
Originally Apple had three partners: Steve
and I each had 45% and Ron Wayne, who
helped with the manual, had 10%. Ron
sold his 10% to us for $800. The Apple II
looked like an outstanding product that
could sell 1,000 a month. We thought we
had hit the big one. The problem was that
we didn't
know how to build a thousand of
something that cost $250 each. Where
would we get $250,000 worth of credit? We
had to look for money. People would come
by the garage and ask, "What's the
market?" I'd say, "A million." They'd say,
"What makes you say that?" And I'd have
too rational an answer: "There's a million
ham radio operators and more people are
getting into computers." There's no way
that answer could be wrong but they
weren't the right words. We got directed
to Mike Markkula, who had wanted to
build computers in the home for quite a
while. He had left Intel with a lot of stock
options and he was still young. He
started developing a business plan and
joined us as a third and equal partner.
For a while I didn't want to leave Hewlett
Packard. Then a friend said to me, "Steve,
you can start this company, manage it
and get rich. Or, Steve, you can start this
company, stay an engineer all your life
and get rich." I realized that I could still
sit down and write code and build things,
and that the company was just a way to
make money. We hired a President who
could get things done. Steve had a friend
at Atari who could design switching power
supplies which required less cooling than
the regular type. Our phony reason for
needing this was our belief that no
computer should have a fan.
We started producing Apple II's. This was
the first computer that you could take out
of the box, plug in, read only a little bit
and start typing, "playing" BASIC. It was
the first computer to be in a plastic case;
it was the first computer to come with
video as standard; it was the first to build
BASIC in ROM; it was the first low cost
computer to come fully assembled; it was
the first to have paddles and sound.
Fortunately it had a lot of memory slots.
While the world only wanted 4K bytes
that year for anything, they thought
maybe 8 sometime, but 48K bytes would
never be needed. In the beginning, The
Commodore, Radio Shack and Apple
machines all sold in about equal
numbers. Then, 8K programs started to
come out and, in 1978, the first
spreadsheet and floppy discs came out.
Both needed more than 8K of RAM. The
Apple was the one of the three that had
expandable memory and could support
spreadsheet or floppy control software.
With Visicalc computers had a different flavor: now you
could walk into a store and buy a
computer with a solution. Our dreams of
people controlling garage doors and
keeping recipes were of much less
importance.
A lot of things happened at Apple because
one of the top managers had a pet project.
One of Mike Markkula's pet ideas was
that recipes and keeping track of the
check-book were going to be principle
uses. So he had Randy Wigginton (who
was to write MacWrite in the future) write
a check-book program in BASIC. Two
things came out of that: a floating point
BASIC to make it easier to write money
handling programs, and the addition of a
floppy disc to make the machine fast. The
current practice had been to use cassette
tapes that took three minutes to load a
program after which you could add the
data for two checks, and then download,
which took another several minutes. We
started to work on both projects. The
floppy disc controllers at the time used
about 50 chips. I had figured out a design
with five chips and thought that I must be
leaving important things out. But after a
lot of analysis of other designs, I found
that mine did even more. So I knew that I
was onto a good winner: real fast, real
small (based on the new 5 and a half inch
disc from Shugart), and real cheap. From
that time, Apple took off. We were
backlogged for four months of orders and
the path had been set.
We premiered the floppy disc at the first
National Computer Conference in Dallas
that allowed microcomputers to be shown.
This completed the initial development of
the Apple II. I don't remember much
about the show, but the hotel was the
first one that I stayed in that had movies
you could dial in your room. I had
designed one of these systems while I
was at Hewlett Packard and I knew that it
has to send your room number down to a
computer. Travelling with our tools, we
opened up the box and saw a bunch of
switches. I just toggled in a different code
on the switches and didn't get billed for
the movies. Randy Wigginton and I looked
at the touchtone phone with different
numbers for room service and so on. 'We
took it apart and rewired the keypad to go
vertically instead of horizontally.
QUESTIONS
There are some things that are
inevitable in history and other things
that depend on a unique individual.
How do you feel about your role?
Almost everything would have happened
about the same time. It turns out that my
whole life was directed to one kind of
computer design and when the window
occurred, I was there. It was great luck for
me.
What is it like to have to use an
assumed name to go to college and to
be a hero?
I used an assumed name and
went back to Berkeley in 1981-2 for a full
year. And I got away with it, because I
wasn't known quite that well then. It was
strange to read about myself. I couldn't
understand why people would want to
come up and shake my hand. Then I met
Ted Turner who was my hero for
challenging the networks and I asked him
for his autograph. I now understand that
we all want to have heros.
How do you feel about the Macintosh?
I love my Macintosh. I brought it on the
trip. I dropped it in the San Francisco
airport but it lived.
What's your relationship with Apple?
Since the computer keeps track of the
employee benefits, I make sure that I get
the minimal salary. I travel on their
behalf, consult with them, and think its a
great company.
What is your new company doing?
CL 9 is working on remote control devices
for the home. It's not going to be a huge
company but it's fun. Right now two
engineers are working together in an
environment where we can do great
things.
Micral,
by R2E, 1973
The Micral is the earliest commercial
non-kit computer based on a
microprocessor. The founder and
president of R2E (Realisations Etudes
Electroniques), Thi T. Truong, created
the Micral as a replacement for
minicomputers in applications where
high performance was not required. He
perceived a big gap between
minicomputers, such as the DEC PDP-8,
on the one hand, and a wired logic
system on the other. As soon as the
Intel 8008 microprocessor was
introduced, he decided to build a
computer to fill this gap.
By May 1973, barely six months after the
Intel 8008 became available, Truong
together with engineers Francois
Gernelle and Ben Chetrite, had the
Micral designed and built. It had some
remarkable similarities to later personal
computers such as a bus system and
slots for expansion. The basic original
model had 256 bytes of RAM, and could
be expanded to 2K with ROMS and
PROMS. It was capable of directly
addressing 16K, and boards to expand
the memory beyond 2K soon became
available. The Micral had a real-time
clock, eight levels of interrupt priority
and automatic enabling and disabling.
The CPU, memory, input/output
interfaces and fast peripheral controllers
all plugged into the Pluribus - a 60-bit
single data bus. There were 52
instructions, oriented towards process-
control and data transmission
applications. Instruction times ranged
from 7.5 to 27.5 microseconds. The Micral had an
assembler and an operating system
which supported a teletype and cassette
recorder connected to the Pluribus. The
machine evolved rapidly, with later
models offering more RAM, floppy discs,
hard discs and a range of standard
software.
