The Following Article Was Published In IEEE Spectrum December 1984
Author Was Fred Guterl, Associate Editor
A small team of little-known designers,
challenged to produce a low-cost, exceptionally easy-to-use personal
computer, turns out a technical milestone
In 1979 the Macintosh personal computer
existed only as the pet idea of Jef Raskin, a veteran of the Apple
II team, who had proposed that Apple Computer Inc. make a low-cost
"appliance"-type computer that would be as easy to use
as a toaster. Mr. Raskin believed the computer he envisioned,
which he called Macintosh, could sell for $1000 if it was manufactured
in high volume and used a powerful microprocessor executing tightly
Mr. Raskin's proposal did not impress anyone
at Apple Computer enough to bring much money from the board of
directors or much respect from Apple engineers. The company had
more pressing concerns at the time: the major Lisa workstation
project was getting under way, and there were problems with the
reliability of the Apple III, the revamped version of the highly
successful Apple II.
Although the odds seemed against it in 1979,
the Macintosh, designed by a handful of inexperienced engineers
and programmers, is now recognized as a technical milestone in
personal computers. Essentially a slimmed-down version of the
Lisa workstation with many of its software features, the Macintosh
sold for $2495 at its introduction in early 1984; the Lisa initially
sold for $10,000. Despite criticism of the Macintosh - that it
lacks networking capabilities adequate for business applications
and is awkward to use for some tasks - the computer is considered
by Apple to be its most important weapon in the war with IBM for
survival in the personal-computer business.
From the beginning, the Macintosh project
was powered by the dedicated drive of two key players on the project
team. For Burrell Smith, who designed the Macintosh digital hardware,
the project represented an opportunity for a relative unknown
to demonstrate outstanding technical talents. For Steven Jobs,
the 29-year-old chairman of Apple and the Macintosh project's
director, it offered a chance to prove himself in the corporate
world after a temporary setback: although he confounded Apple
Computer, the company had declined to let him manage the Lisa
project. Mr. Jobs contributed relatively little to the technical
design of the Macintosh, but he had a clear vision of the product
from the beginning. He challenged the project team to design the
best product possible and encouraged the team by shielding them
from bureaucratic pressures within the company.
The early design
Mr. Smith, who was a repairman in the Apple
II maintenance department in 1979, had become hooked on microprocessors
several years earlier during a visit to the electronics-industry
area south of San Francisco known as Silicon Valley. He dropped
out of liberal-arts studies at the Junior College of Albany, New
York, to pursue the possibilities of microprocessors - there isn't
anything you can't do with those things, he thought. Mr. Smith
later became a repairman at Apple Computer, in Cupertino, Calif.,
where he spent much time studying the cryptic logic circuitry
of the Apple II, designed by company cofounder Steven Wozniak.
Mr. Smith's dexterity in the shop impressed
Bill Atkinson, one of the Lisa designers, who introduced him to
Mr. Raskin as "the man who's going to design your Macintosh."
Mr. Raskin replied noncommittally, "We'll see about that."
However, Mr. Smith managed to learn enough
about Mr. Raskin's conception of the Macintosh to whip up a makeshift
prototype using a Motorola 6809 microprocessor, a television monitor,
and an Apple II. He showed it to Mr. Raskin, who was impressed
enough to make him the second member of the Macintosh team.
But the fledgling Macintosh project was
in trouble. The Apple board of directors wanted to cancel the
project in September 1980 to concentrate on more important projects,
but Mr. Raskin was able to win a three-month reprieve.
Meanwhile Steve Jobs, then vice president
of Apple, was having trouble with his own credibility within the
company. Though he had sought to manage the Lisa computer project,
the other Apple executives saw him too inexperienced and eccentric
to entrust him with such a major undertaking, and he had no formal
business education. After this rejection, "he didn't like
the lack of control he had," noted one Apple executive. "He
was looking for his niche."
Mr. Jobs became interested in the Macintosh
project, and, possibly because few in the company thought the
project had a future, Mr. Jobs was made its manager. Under his
direction, the design team became as compact and efficient as
the Macintosh was to be - a group of engineers working at a distance
from all the meetings and paper-pushing of the corporate mainstream.
Mr. Jobs, in recruiting the other members of the Macintosh team,
lured some from other companies with promises of potentially lucrative
With Mr. Jobs at the helm, the project gained
some credibility among the board of directors - but not much.
According to one team member, it was known in the company as "Steve's
folly." But Mr. Jobs lobbied for a bigger budget for the
project and got it. The Macintosh team grew to 20 by early 1981.
The decision on what form the Macintosh
would take was left largely to the design group. At first the
members had only the basic principles set forth by Mr. Raskin
and Mr. Jobs to guide them, as well as the example set by the
Lisa project. The new machine was to be easy to use and inexpensive
to manufacture. Mr. Jobs wanted to commit enough money to build
an automated factory that would produce about 300,000 computers
a year. So one key challenge for the design group was to use inexpensive
parts and to keep the parts count low.
Making the computer easy to use required
considerable software for the user- computer interface. The model
was, of course, the Lisa workstation with its graphic "windows:
to display simultaneously many different programs. "Icons,"
or little pictures, were used instead of cryptic computer terms
to represent a selection of programs on the screen; by moving
a "mouse," a box the size of a pack of cigarettes, the
user manipulated a cursor on the screen. The Macintosh team redesigned
the software of the Lisa from scratch to make it operate more
efficiently, since the Macintosh was to have far less memory than
the 1 million bytes of the Lisa. But the Macintosh software was
also required to operate quicker than the Lisa software, which
had been criticized for being slow.
A free hand to explore
The lack of a precise definition for the
Macintosh project was not a problem. Many of the designers preferred
to define the computer as they went along. "Steve allowed
use to crystallize the problem and the solution simultaneously,"
recalled Mr. Smith. The method put strain on the design team,
since they were continually evaluating design alternatives. "We
were swamped in detail," Mr. Smith said. But this way of
working also led to a better product, the designers said, because
they had the freedom to seize opportunities during the design
stage to enhance the product.
Such freedom would not have been possible
had the Macintosh project been structured in the conventional
way at Apple, according to several of the designers. "No
one tried to control us," said one. "Some managers like
to take control, and though that may be good for mundane engineers,
it isn't good if you are self-motivated."
Central to the success of this method was
the small, closely knit nature of the design group, with each
member being responsible for a relatively large portion of the
total design and free to consult other members of the team when
considering alternatives. For example, Mr. Smith, who was well
acquainted with the price of electronic components from his early
work on reducing the cost of the Apple II, made many decisions
about the economics of Macintosh hardware without time-consuming
consultations with purchasing agents. Because communication among
team members was good, the designers shared their areas of expertise
by advising each other in the working stages, rather than waiting
for a final evaluation from a group of manufacturing engineers.
Housing all members of the design team in
one small office made communicating easier. For example, it was
simple for Mr. Smith to consult a purchasing agent about the price
of parts if he needed to, because the purchasing agent worked
in the same building.
Andy Hertzfeld, who transferred from the
Apple II software group to design the Macintosh operating software,
noted, "In lots of other projects at Apple, people argue
about ideas. But sometimes bright people think a little differently.
Somebody like Burrell Smith would design a computer on paper and
people would say, "It'll never work." So instead Burrell
builds it lightning fast and has it working before the guy can
The closeness of the Macintosh group enabled
it to make design tradeoffs that would not have been possible
in a large organization, the team members contended. The interplay
between hardware and software was crucial to the success of the
Macintosh design, using a limited memory and few electronic parts
to perform complex operations. Mr. Smith, who was in charge of
the computer's entire digital-hardware design, and Mr. Hertzfeld
became close friends and often collaborated. "When you have
one person designing the whole computer," Mr.. Hertzfeld
observed, "he knows that a little leftover gate in one part
may be used in another part."
To promote interaction among the designers,
one of the first things that Mr. Jobs did in taking over the Macintosh
project was to arrange special office space for the team. In contrast
to Apple's corporate headquarters, identified by the company logo
on a sign on its well-trimmed lawn, the team's new quarters, behind
a Texaco service station, had no sign to identify them and no
listing in the company telephone directory. The office, dubbed
Texaco Towers, was an upstairs, low-rent, plasterboard-walled,
"tacky-carpeted" place, "the kind you'd find at
a small law outfit," according to Chris Espinosa, a veteran
of the original Apple design team and an early Macintosh draftee.
It resembled a house more than an office, having a communal area
much like a living room, with smaller rooms off to the side for
more privacy in working or talking. The decor was part college
dormitory, part electronic repair shop: art posters, bean-bag
chairs, coffee machines, stereo systems, and electronic equipment
of all sorts scattered about.
There were no set work hours and initially
not even a schedule for the development of the Macintosh. Each
week, if Mr. Jobs was in town (often he was not), he would hold
a meeting at which the team members would report what they had
done the previous week. One of the designers' sidelines was to
dissect the products of their competitors. "Whenever a competitor
came out with a product, we would buy and dismantle it, and it
would kick around the office," recalled Mr. Espinosa.
In this way, they learned what they did
not want their product to be. In their competitors' products,
Mr. Smith saw a propensity for using connectors and slots for
inserting printed-circuit boards - a slot for the video circuitry,
a slot for the keyboard circuitry, a slot for the disk drives,
and memory slots. Behind each slot were buffers to allow signals
to pass onto and off the printed-circuit board properly. The buffers
meant delays in the computers' operations, since several boards
shared a backplane, and the huge capacitance required for multiple
PC boards slowed the backplane. The number of parts required made
the competitors' computers hard to manufacture, costly, and less
reliable. The Macintosh team resolved that their PC would have
but two printed-circuit boards and no slots, buffers, or backplane.
To squeeze the needed components onto the
board, Mr. Smith planned the Macintosh to perform specific functions
rather than operate as a flexible computer that could be tailored
by programmers for a wide variety of applications. By rigidly
defining the configuration of the Macintosh and the functions
it would perform, he eliminated much circuitry. Instead of providing
slots into which the user could insert printed-circuit boards
with such hardware as memory or coprocessors, the designers decided
to incorporate many of the basic functions of the computer in
read-only memory, which is more reliable. The computer would be
expanded not by slots, but through a high-speed serial port.
Simplifying the software
The software designers were faced in the
beginning with often-unrealistic schedules. "We looked for
any place where we could beg, borrow, or steal code," Mr.
Hertzfeld recalled. The obvious place for them to look was the
Lisa workstation. The Macintosh team wanted to borrow some of
the Lisa's software for drawing graphics on the bit-mapped display.
In 1981, Bill Atkinson was refining the Lisa graphics software,
called Quickdraw, and began to work part-time implementing it
for the Macintosh.
Quickdraw was a scheme for manipulating
bit maps to enable applications programmers to construct images
easily on the Macintosh bit-mapped display. The Quickdraw program
allows the programmer to define and manipulate a region - a software
representation of an arbitrarily shaped area of the screen. One
such region is a rectangular window with rounded corners, used
throughout the Macintosh software. Quickdraw also allows the programmer
to keep images within defined boundaries, which makes the windows
in the Macintosh software appear to hold data. The programmer
can unite two regions, subtract one from the other, or intersect
In Macintosh, the Quickdraw program was
to be tightly written in assembly-level code and etched permanently
in ROM. It would serve as a foundation for higher-level software
to make use of graphics.
Quickdraw was "an amazing graphics
package," Mr. Hertzfeld noted, but it would have strained
the capabilities of the 6809 microprocessor, the heart of the
early Macintosh prototype. Motorola Corp. announced in late 1980
that the 68000 microprocessor was available, but that chip was
new and unproven in the field, and at $200 a piece it was also
expensive. Reasoning that the price of the chip would come down
before Apple was ready to start mass-producing the Macintosh,
the Macintosh designers decided to gamble on the Motorola chip.
Another early design question for the Macintosh
was whether to use the Lisa operating system. Since the Lisa was
still in the early stages of design, considerable development
would have been required to tailor its operating system for the
Macintosh. Even if the Lisa had been completed, rewriting its
software in assembly code would have been required for the far
smaller memory of the Macintosh. In addition, the Lisa was to
have a multitasking operating system from scratch, working from
the basic concepts of the Lisa. Simplifying the Macintosh operating
system posed the delicate problem of restricting the computer's
memory capacity enough to keep it inexpensive but not so much
as to make it inflexible.
The Macintosh would have no multitasking
capability but would execute only one applications program at
a time. Generally, a multitasking operating system tracks the
progress of each of the programs it is running and then stores
the entire state of each program - the values of its variables,
the location of the program counter, and so on. This complex operation
requires more memory and hardware than the Macintosh designers
could afford. However, the illusion of multitasking was created
by small programs built into the Macintosh system software. Since
these small programs - such as one that creates the images of
a calculator on the screen and does simple arithmetic - operate
in areas of memory separate from applications, they can run simultaneously
with applications programs [Fig. 1].
Since the Macintosh used a memory-mapped
scheme, the 68000 microprocessor required no memory management,
simplifying both the hardware and the software. For example, the
68000 has two modes for operation: a user mode, which is restricted
so that a programmer cannot inadvertently upset the memory-management
scheme; and a supervisor mode, which allows unrestricted access
to all of the 68000's commands. Each mode uses its own stack of
pointers to blocks of memory. The 68000 was rigged to run only
in the supervisor mode, eliminating the need for the additional
stack. Although seven levels of interrupts were available for
the 68000, only three were used.
Another simplification was made in the Macintosh's
file structure, exploiting the small disk space with only one
or two floppy-disk drives. In the Lisa and most other operating
systems, two indexes access a program on floppy disk, using up
precious random-access memory and increasing the delay in fetching
programs from a disk. The designers decided to use only one index
for the Macintosh - a block map, located in RAM, to indicate the
location of a program on a disk. Each block map represented one
volume of disk space.
This scheme ran into unexpected difficulties
and may be modified in future versions of the Macintosh, Mr. Hertzfeld
said. Initially, the Macintosh was not intended for business users,
but as the design progressed and it became apparent that the Macintosh
would cost more than expected, Apple shifted its marketing plan
to target business users. Many of them add hard disk drives to
the Macintosh, making the block-map scheme unwieldy.
By January 1982, Mr. Hertzfeld began working
on software for the Macintosh, perhaps the computer's most distinctive
feature, which he called the user-interface toolbox.
The toolbox was envisioned as a set of software
routines for constructing the windows, pull-down menus, scroll
bars, icons, and other graphic objects in the Macintosh operating
system. Since RAM space would be scarce on the Macintosh (it initially
was to have only 64 kilobytes), the toolbox routines were to be
a part of the Macintosh's operating software; they would use the
Quickdraw routines and operates in ROM.
It was important, however, not to handicap
applications programmers - who could boost sales of the Macintosh
by writing programs for it - by restricting them to only a few
toolbox routines in ROM. So the toolbox code was designed to fetch
definition functions - routines that use Quickdraw to create a
graphic image such as a window - from either the system disk or
an application disk. In this way, an applications programmer could
add definition functions for a program, which Apple could incorporate
in later versions of the Macintosh by modifying the system disk.
"We were nervous about putting [the toolbox] in ROM,"
recalled Mr. Hertzfeld, "We knew that after the Macintosh
was out, programmers would want to add to the toolbox routines."
Although the user could operate only one
applications program at a time, he could transfer text or graphics
from one applications program to another with a toolbox routine
called scrapbook. Since the scrapbook and the rest of the toolbox
routines were located in ROM, they could run along with applications
programs, giving the illusion of multitasking. The user would
cut text from one program into the scrapbook, close the program,
open another, and paste the text from the scrapbook. Other routines
in the toolbox, such as the calculator, could also operate simultaneously
with applications programs.
Late in the design of the Macintosh software,
the designers realized that, to market the Macintosh in non-English-speaking
countries, an easy way of translating text in programs into foreign
languages was needed. Thus computer code and data were separated
in the software to allow translation without unraveling a complex
computer program, by scanning the data portion of a program. No
programmer would be needed for translation.
Gambling on the 68000
The 68000, with a 16-bit data bus and 32-bit
internal registers and a 7.83-megahertz clock, could grab data
in relatively large chunks. Mr. Smith dispensed with separate
controllers for the mouse, the disk drives, and other peripheral
functions. "We were able to leverage off slave devices,"
Mr. Smith explained, "and we had enough throughput to deal
with those devices in a way that appeared concurrent to the user."
When Mr. Smith suggested implementing the
mouse without a separate controller, several members of the design
team argued that if the main microprocessor was interrupted each
time the mouse was moved, the movement of the cursor on the screen
would always lag. Only when Mr. Smith got the prototype up and
running were they convinced it would work.
Likewise, in the second prototype, the disk
drives were controlled by the main microprocessor. "In other
computers," Mr. Smith noted, "the disk controller is
a brick wall between the disk and the CPU, and you end up with
a poor-performance, expensive disk that you can lose control of.
It's like buying a brand new car complete with a chauffeur who
insists on driving everywhere."
The 68000 was assigned many duties of the
disk controller and was linked with a disk-controller circuit
built by Mr. Wooziness for the Apple II. "Instead of a wimpy
little 8-bit microprocessor out there, we have this incredible
68000 - it's the world's best disk controller," Mr. Smith
Direct-memory access circuitry was designed
to allow the video screen to share RAM with the 68000. Thus the
68000 would have access to RAM at half speed during the live portion
of the horizontal line of the video screen and at full speed during
the horizontal and vertical retrace [Fig. 2].
While building the next prototype, Mr. Smith
saw several ways to save on digital circuitry and increase the
execution speed of the Macintosh. The 68000 instruction set allowed
Mr. Smith to embed subroutines in ROM. Since the 68000 has exclusive
use of the address and data buses of the ROM, it has access to
the ROM routines at up to the full clock speed. The ROM serves
somewhat as a high-speed cache memory.
The next major revision in the original
concept of the Macintosh was made in the computer's display. Mr.
Raskin had proposed a computer that could be hooked up to a standard
television set. However, it became clear early on that the resolution
of television display was too coarse for the Macintosh. After
a bit of research, the designers found they could increase the
display resolution from 256 by 256 dots to 384 by 256 dots by
including a display with the computer. This added to the estimated
price of the Macintosh, but the designers considered it a reasonable
To keep the parts count low, the two input/output
ports of the Macintosh were to be serial. The decision to go with
this was a serious one, since the future usefulness of the computer
depended largely on its efficiency when hooked up to printers,
local-area networks, and other peripherals. In the early stages
of development, the Macintosh was not intended to be a business
product, which would have made networking a high priority.
The key factor in the decision to use one
high-speed serial port was the introduction in the spring of 1981
of the Zilog Corp.'s 85530 serial-communication controller, a
single chip to replace two less expensive conventional parts -
"vanilla" chips - in the Macintosh. The risks in using
the Zilog chip were that it had not been proven in the field and
it was expensive, almost $9 a piece. In addition Apple had a hard
time convincing Zilog that it seriously intended to order the
part in high volumes for the Macintosh.
"We had an image problem," explained
Mr. Espinosa. "We wore T-shirts and blue jeans with holes
in the knees, and we had a maniacal conviction that we were right
about the Macintosh, and that put some people off. Also, Apple
hadn't yet sold a million Apple IIs. How were we to convince them
that we would sell a million Macs?
In the end, Apple got a commitment from
Zilog to supply the part, with Mr. Espinosa attributes to the
negotiating talents of Mr. Jobs. The serial input/output ports
"gave us essentially the same bandwidth that a memory-mapped
port would," Mr. Smith said. Peripherals were connected to
serial ports in a daisy-chain configuration with the Applebus
Designing a factory without a product
In the fall of 1981, as Mr. Smith worked
on the fourth Macintosh prototype, the design for the Macintosh
factory was getting under way. Mr. Jobs hired Debi Coleman, who
was then working as financial manager at Hewlett-Packard Co. in
Cupertino, Calif., to handle the finances of the Macintosh project.
A graduate of Stanford University with a master's degree in business
administration, Ms. Coleman was a member of a task force at HP
that was studying factories, quality management, and inventory
management. This was good training for Apple, for Mr. Jobs was
intent on using such concepts to build a highly automated manufacturing
plant for the Macintosh in the United States. Briefly he considered
building the plant in Texas, but since the designers were to work
closely with the manufacturing team in the later stages of the
Macintosh design, he decided to locate the plant at Freemont,
Calif., less than a half-hour's drive from Apple's Cupertino headquarters.
Mr. Jobs and other members of the Macintosh
team made frequent tours of automated plants in various industries,
particularly in Japan. At long meetings held after the visits,
the manufacturing group discussed whether to borrow certain methods
they had observed.
The Macintosh factory design was based on
two major concepts. The first was "just-in-time" inventory,
calling for vendors to deliver parts for the Macintosh frequently,
in small lots, to avoid excessive handling of components at the
factory and reduce damage and storage costs. The second concept
was zero-defect parts, with any defect on the manufacturing line
immediately traced to its source and rectified to prevent recurrence
of the error.
The factory, which was to churn out about
a half million Macintosh computers a year (the number kept increasing),
was designed to be built in three stages: first, equipped with
stations for workers to insert some Macintosh components, delivered
to them by simple robots; second, with robots to insert components
instead of workers; and third, many years in the future, with
"integrated" automation, requiring virtually no human
In building the factory, "Steve was
willing to chuck all the traditional ideas about manufacturing
and the relationship between design and manufacturing," Ms
Coleman noted. "He was willing to spend whatever it cost
to experiment in this factory. We planned to have a major revision
every two years."
By late 1982, before Mr. Smith had designed
the final Macintosh prototype, the designs of most of the factory's
major subassemblies were frozen, and the assembly stations could
be designed. About 85 percent of the components on the digital-logic
printed-circuit board were to be inserted automatically [Fig.
3], and the remaining 15 percent were to be surface-mounted devices
inserted manually at first and by robots in the second stage of
the factory. The production lines for automatic insertion were
laid out to be flexible; the number of stations was not defined
until trial runs were made. The materials-delivery system, designed
with the help of engineers recruited from Texas Instruments in
Dallas, Texas, divided small and large parts between receiving
doors at the materials distribution center. The finished Macintoshes
coming down the conveyor belt were to be wrapped in plastic and
stuffed into boxes using equipment adapted from machines used
in the wine industry for packaging bottles.
As factory construction progressed, pressure
built on the Macintosh design team to deliver a final prototype.
the designers had been working long hours but with no deadline
set for the computer's introduction. That changed in the middle
of 1981, after Mr. Jobs imposed a tough and sometimes unrealistic
schedule, reminding the team repeatedly that "real artist
ship" a finished product. In the late 1981, when IBM announced
its personal computer, the Macintosh marketing staff began to
refer to a "window of opportunity" that made it urgent
to get the Macintosh to customers.
"We had been saying, "We're going
to finish in six months' for two years," Mr. Hertzfeld recalled.
The new urgency led to a series of design
problems that seemed to threaten the Macintosh dream.
Facing impossible deadlines
The computer's circuit density was one bottleneck.
Mr. Smith had trouble paring enough circuitry off his first two
prototypes to squeeze them onto one logic board. In addition he
needed faster circuitry for the Macintosh display. The horizontal
resolution was only 384 dots - not enough room for the 80 characters
of text needed for the Macintosh to compete as a word processor.
One suggested solution was to use the word-processing software
to allow an 80-character line to be seen by horizontal scrolling.
However, most standard computer displays were capable of holding
80 characters, and the portable computers with less capability
were very inconvenient to use.
Another problem with the Macintosh display
was its limited dot density. Although the analog circuitry, which
was being designed by Apple engineer George Crow, accommodated
512 dots on the horizontal axis, Mr. Smith's digital circuitry
- which consisted of bipolar logic arrays - did not operate fast
enough to generate the dots. Faster bipolar circuitry was considered
but rejected because of its high power dissipation and its cost.
Mr. Smith could think of but one alternative: combine the video
and other miscellaneous circuitry on a single custom n-channel
Mr. Smith began designing such a chip in
February 1982. During the next six months the size of the hypothetical
chip kept growing. Mr. Jobs set a shipping target of May 1983
for the Macintosh but, with a backlog of other design problems,
Burrell Smith still had not finished designing the custom chip.
which was named after him: the IBM (Integrated Burrell Machine)
Meanwhile, the Macintosh offices were moved
from Texaco Towers to more spacious quarters at the Apple headquarters,
since the Macintosh staff had swelled to about 40. One of the
new employees was Robert Belleville, whose previous employer was
the Xerox Palo Alto Research Corp. At Xerox he had designed the
hardware for the Star workstation-which, with its window, icons,
and mouse, might be considered an early prototype of the Macintosh.
When Mr. Jobs offered him a spot on the Macintosh team, Mr. Belleville
was impatiently waiting for authorization from Xerox to proceed
on a project he had proposed that was similar to the Macintosh
- a low-cost version of the Star.
As the new head of the Macintosh engineering,
Mr. Belleville faced the task of directing Mr. Smith, who was
proceeding on what looked more and more like a dead-end course.
Despite the looming deadlines, Mr. Belleville tried a soft-sell
"I asked Burrell if he really needed
the custom chip," Mr. Belleville recalled. "He said
yes. I told him to think about trying something else."
After thinking about the problem for three
months, Mr. Smith concluded in July 1982 that "the difference
in size between this chip and the state of Rhode Island is not
very great." He then set out to design the circuitry with
higher-speed programmable-array logic-as he had started to do
six months earlier. He had assumed that higher resolution in the
horizontal video required a faster clock speed. But he realized
that he could achieve the same effect with clever use of faster
bipolar-logic chips that had become available only a few months
earlier. By adding several high-speed logic circuits and a few
ordinary circuits, he pushed the resolution up to 512 dots.
Another advantage was that the PALs were
a mature technology and their electrical parameters could tolerate
large variations from the specified values, making the Macintosh
more stable and more reliable-important characteristics for a
so-called appliance product. Since the electrical characteristics
of each integrated circuit may vary from those of other ICs made
in different batches, the sum of the variances of 50 or so components
in a computer may be large enough to threaten the system's integrity.
Even as late as the summer of 1982, with
one deadline after another blown, the Macintosh designers were
finding ways of adding features to computer. After the team disagreed
over the choice of a white background for the video with black
characters or the more typical white-on-black, it was suggested
that both options be made available to the user through a switch
on the back of the Macintosh. But this compromise led to debates
about other questions.
"It became an intense and almost religious
argument," recalled Mr. Espinosa, "about the purity
of the system's design versus the user's freedom to configure
the system he liked. We had weeks of argument over whether to
add a few pennies to the cost of the machine."
Improvements through competition
The designers, being committed to the Macintosh,
often worked long hours to refine the system. A programmer might
spend many night hours to reduce the time needed to format a disk
from three minutes to one. The reasoning was that expenditure
of a Macintosh programmer's time amounted to little in comparison
with reduction of two minutes in the formatting times. "If
you take two extra minutes in the formatting time, times a million
people, times 50 disks to format, that's a lot of the world's
time." Mr. Espinosa explained.
But if the group's commitment to refinements
often kept them from meeting deadlines, it paid off in tangible
design improvements. "There was a lot of competition for
doing something very bright and creative and amazing," said
Mr. Espinosa. "People were so bright that it became a contest
to astonish them."
The Macintosh team's approach to working
- "like a chautauqua, with daylong affairs where people would
sit and talk about how they were going to do this or that"
- sparked creative thinking about the Macintosh's capabilities.
When a programmer and a hardware designer started to discuss how
to implement the sound generator, for instance, they were joined
by one of several nontechnical members of the team - marketing
staff, finance specialists, secretaries - who remarked how much
fun it would be if the Macintosh could sound four distinct voices
at once so the user could program it to play music. That possibility
excited the programmer and the hardware engineer enough to spend
extra hours in designing a sound generator with four voices.
The payoff of such discussions with nontechnical
team members, Mr. Espinosa said "was coming up with all those
glaringly evident things that only somebody completely ignorant
could come up with. If you immerse yourself in a group that doesn't
know the technical limitations, then you get a group mania to
try and deny those limitations. You start trying to do the impossible
- and once in a while succeeding."
The sound generator in the original Macintosh
was quite simple - a one-bit register connected to a speaker.
To vibrate the speaker, the programmer wrote a software lop that
changed the value of the register from one to zero repeatedly.
Nobody had even considered designing a four-voice generator -
that is, not until "group mania" set in.
Mr. Smith was pondering this problem when
he noticed that the video circuitry was very similar to the sound-generator
circuitry. Since the video was bit-mapped, a bit of memory represented
one dot on the video screen. The bits that made up a complete
video image were held in a block of RAM and fetched by a scanning
circuit to generate the image. Sound circuitry required similar
scanning, with data in memory corresponding to the amplitude and
frequency of the sound emanating from the speaker.
Mr. Smith reasoned that by adding a pulse-width-modulator
circuit, the video circuitry could be used to generate sound during
the last microsecond of the horizontal retrace - the time it took
the electron bean in the cathode-ray tube of the display to move
from the last dot on each line to the first dot of the next line.
During the retrace the video-scanning circuitry jumped to a block
of memory earmarked for the amplitude value of the sound wave,
fetched bytes, deposited them in a buffer that fed the sound generator,
and then jumped back to the video memory in time for the next
trace. The sound generator was simply a digital-to-analog converter
connected to a linear amplifier.
To enable the sound generator to produce
four distinct voices, software routines were written and embedded
in ROM to accept values representing four separate sound waves
and convert them onto one complex wave. Thus a programmer writing
applications programs for the Macintosh could specify separately
each voice without being concerned about the nature of the complex
Gearing up for production
In the fall of 1982, as the factory was
being built and the design of the Macintosh was approaching its
final form. Mr. Jobs began to play a greater role in the day-to-day
activities of the designers. Although the hardware for the sound
generator had been designed, the software to enable the computer
to make sounds had not yet been written by Mr. Hertzfeld, who
considered other parts of the Macintosh software more urgent.
Mr. Jobs had been told that the sound generator would be impressive,
with the analog circuitry and the speaker having been upgraded
to accommodate four voices. But since this was an additional hardware
expense, with no audible results at that point, one Friday Mr.
Jobs issued an ultimatum: "If I don't hear sound out of this
thing by Monday morning, we're ripping out the amplifier."
That motivation sent Mr. Hertzfeld to the
office during the weekend to write the software. By Sunday afternoon
only three voices were working. He telephoned his colleague Mr.
Smith and asked him to stop by and help optimize the software.
"Do you mean to tell me you're using
subroutines!" Mr. Smith exclaimed after examining the problem.
"No wonder you can't get four voices. Subroutines are much
By Monday morning, the pair had written
the microcode programs to produce results that satisfied Mr. Jobs.
Although Mr. Jobs's input was sometimes
hard to define, his instinct for defining the Macintosh as a product
was important to its success, according to the designers. "He
would say, 'This isn't what I want. I don't know what I want,
but this isn't it.' " Mr. Smith said.
"He knows what great products are,"
noted Mr. Hertzfeld. "He intuitively knows what people want."
One example was the design of the Macintosh
casing, when clay models were made to demonstrate various possibilities.
"I could hardly tell the difference between two models,"
Mr. Hertzfeld said. "Steve would walk in and say, 'This one
stinks and this one is great.' And he was usually right.
Because Mr. Jobs placed great emphasis on
packaging the Macintosh to occupy little space on a desk, a vertical
design was used, with the disk drive placed underneath the CRT.
Mr. Jobs also decreed that the Macintosh
contain no fans, which he had tried to eliminate from the original
Apple computer. A vent was added to the Macintosh casing to allow
cool air to enter and absorb heat from the vertical power supply,
with hot air escaping at the top. The logic board was horizontally
Mr. Jobs, however, at times gave unworkable
orders. When he demanded that the designers reposition the RAM
chips on an early printed-circuit board because they were too
close together, "most people chortled," one designer
said. The board was redesigned with the chips farther apart, but
it did not work because the signals from the chips took too long
to propagate over the increased distance. The board was redesigned
again to move the chips back to their original position.
A problem in radiation
When the design group started to concentrate
on manufacturing, the most imposing task was preventing radiation
from leaking form the Macintosh's plastic casing. At one time
the fate of the Apple II had hung in the balance as its designers
tried unsuccessfully to meet the emissions standards of the Federal
Communications Commission. "I quickly saw the number of Apple
II components double when several inductors and about 50 capacitors
were added to the printed-circuit boards," Mr. Smith recalled.
With the Macintosh, however, he continued, "we eliminated
all of the discrete electronics by going to a connectorless and
solderless design; we had had our noses rubbed in the FCC regulations,
and we knew how important that was." The high-speed serial
I/O ports caused little interference because they were easy to
Another question that arose toward the end
of the design was the means of testing the Macintosh. In line
with the zero-defect concept, the Macintosh team devised software
for factory workers to use in debugging faults in the printed-circuit
boards, as well as self-testing routines for the Macintosh itself.
The disk controller is tested with the video
circuits. Video signals sent into the disk controller are read
by the microprocessor. "We can display on the screen the
pattern we were supposed to received and the pattern we did receive
when reading off the disk," Mr. Smith explained, "and
other kinds of prepared information about errors and where they
occurred on the disk."
To test the printed-circuit boards in the
factory, the Macintosh engineers designed software for a custom
bed-of-nails tester that checks each computer in only a few seconds,
faster than off-the-shelf testers. If a board fails when a factory
worker places it on the tester, the board is handed to another
worker who runs a diagnostic test on it. A third worker repairs
the board and returns it to the production line.
When Apple completed building the Macintosh
factory, at an investment of $20 million, the design team spent
most of its time there, helping the manufacturing engineers get
the production lines moving. Problems with the disk drives in
the middle of 1983 required Mr. Smith to redesign his final prototype
Some of the plans for the factory proved
troublesome, according to Ms. Coleman. The automatic insertion
scheme for discrete components was unexpectedly difficult to implement.
Many of the precise specifications for the geometric and electrical
properties of the parts had to be reworked several times. Machines
proved to be needed to align many of the parts before they were
inserted. Although the machines, at $2000 a piece, were not expensive,
they were last-minute requirement.
The factory had few major difficulties with
its first experimental run in December 1983, although the project
had slipped from its May 1983 deadline. Often the factory would
stop completely while engineers busily traced the faults to the
sources - part of the zero-defect approach. Mr. Smith and the
other design engineers virtually lived in the factory that December.
In January 1984 the first salable Macintosh
computer rolled off the line. Although the production rate was
erratic at first, it has since settled at one Macintosh every
27 seconds - about a half million a year.
Creating the 'shelf space' for sales
The marketing of the Macintosh shaped up
much like the marketing of a new shampoo or soft drink, according
to Mike Murray, who was hired in 1982 as the third member of the
Macintosh marketing staff. "If Pepsi has tow times more shelf
space than Coke," he explained, "you will sell more
Pepsi. We want to create shelf space in your mind for the Macintosh."
To create that space on a shelf already
crowded by IBM, Tandy, and other computer companies, Apple launched
an aggressive advertising campaign - its most expensive ever.
Mr. Murray proposed the first formal marketing
budget for the Macintosh in late 1983: he asked for $40 million.
"People literally laughed at me," he recalled. "They
said, 'What kind of a yo-yo is this guy?' " He didn't get
his $40 million budget, but he got close to it - $30 million.
The marketing campaign started before the
Macintosh was introduced. Television viewers watching the Super
Bowl football game in January 1984 saw a commercial with the Macintosh
over-coming Orwell's nightmare vision of 1984.
Other television advertisements. as well
as magazine and billboard ads, depicted the Macintosh as being
easy to learn to use. In some ads, the Mad was positioned directly
alongside IBM's personal computer. Elaborate color foldouts in
major magazines pictured the Macintosh and members of the design
"The interesting thing about this business,"
mused Mr. Murray, "is that there is no history. The best
way is to come in really smart, really understand the fundamentals
of the technology and how the software dealers work, and then
run as fast as you can."
The future challenge
"We've established a beachhead with
the Macintosh," explained Mr. Murray. "We're on the
beach. If IBM knew in their heart of hearts how aggressive and
driven we are, they would push us off the beach right now, and
I think they're trying. The next 18 to 24 months is do-or-die
time for us."
With sales of the Lisa workstation disappointing,
Apple is counting on the Macintosh to survive. The ability to
bring out a successful family of products is seen as a key to
that goal, and the company is working on a series of Macintosh
peripherals - printers, local-area networks, and the like. This,
too, is proving both a technical and organizational challenge.
"Once you go from a stand-alone system
to a networked one, the complexity increases enormously,"
noted Mr. Murray. "We cannot throw it all out into the marker
and let people tell us what is wrong with it. We have to walk
before we can run."
Only two software programs were written
by Apple for the Macintosh - Macpaint, which allows users to draw
pictures with the mouse, and Macwrite, a word-processing program.
Apple is counting on independent software vendors to write and
marker applications programs for the Macintosh that will make
it a more attractive product for potential customers. The company
is also modifying some Lisa software for use on Macintosh and
making versions of the Macintosh software to run on the Lisa.
Meanwhile the small, coherent Macintosh
design team is no longer. "Nowadays we're a large company,"
Mr. Smith remarked.
"The pendulum of the project swings,"
explained Mr. Hertzfeld, who has taken a leave of absence from
Apple. "Now the company is more mainstream organization,
with managers who have managers working for them. That's why I'm
not there, because I got spoiled" working on the Macintosh
To probe further
This article is part of a design-case history
series appearing periodically in Spectrum. The previous installment
was "The Atari video computer system" [March 1983, p.
A description of the Macintosh hardware
and software can be found in the February 1984 issue of Byte magazine
(McGraw-Hill Publications, New York), including articles by Mr.
Smith and Mr. Hertzfeld.
For information on Apple Computer Inc.'s
Lisa workstation, see "Personal computers" in the January
1984 Spectrum [p.41]. The Xerox Star workstation was discussed
in "Chips oust clips" [April 1983, p.42].
For product information about the Macintosh,
write to Apple Computer Inc., 20525 Mariani Ave., Cupertino, Calif.
95014; telephone 408-996-1010.
electrical connection common to two or more printed-circuit boards.
Bit-mapped graphics: a
method of representing data in a computer for display in which
each dot on the screen is mapped to a unit of data in memory.
memory for holding data temporarily between processes.
Direct-memory access: a
mechanism in a computer that bypasses the central processing unit
to gain access to memory. It is often used when large blocks of
data are transferred from memory to a peripheral.
graphic images on a computer screen that represent functions or
programs; for example, a wastebasket designates a delete operations.
Memory management: a
mechanism in a computer for allocating internal memory among different
programs, especially in multitasking systems.
Mouse: a box the size of a cigarette pack used to move a cursor on a computer
screen. the movement of the cursor matches
the movement of the mouse. The mouse also may have one or more
buttons for selecting commands on a menu.
simultaneous execution of two or more applications programs in
a computer (also known as concurrency).
Operating System: a
computer program that performs basic operations, such as governing
the allocation of memory, accepting interrupts from peripherals,
and opening and closing files.
Programmable-array logic: an
array of logic elements that are mass-produced without interconnections
and that are interconnected at the specification of the user at
the time of purchase.
section of a computer code that is represented symbolically in
rectangularly shaped image on a computer screen within which the
user writes and reads data, representing a program in the computer.
 Embedding Macintosh software in 64 kilobytes
of read-only memory increased the reliability of the computer
and simplified the hardware [A]. About one third of the ROM software
is the operating system. One third is taken up by Quickdraw, a
program for representing shapes and images for the bit-mapped
display. The remaining third is devoted to the user-interface
toolbox, which handles the display of windows, text editing, menus,
and the like. The user interface of the Macintosh includes pulldown
menus, which appear only when the cursor is placed over the menu
name and a button on the mouse is pressed. Above, a user examining
the 'file' menu selects the open command, which causes the computer
to load the file (indicated by darkened icon) from disk into internal
memory. The Macintosh software was designed to make the toolbox
routines optional for programmers; the applications program offers
the choice of whether or not to handle an event [B].
I. Macintosh prototypes
|1. December 1979||500||Based on the Motorola 6809 microproc-
essor, with 64 kilobytes of random-access
memory, using television display with a resolution of 256 by 256 dots
|2. January 1981||1000||Changed to the 68000 microprocessor, increased resolution to 356 by 256 dots by incorporating a CRT|
|3. June 1981||Added Zilog high-speed serial port|
|4. February 1982||Redesigned computer around custom CMOS chip|
|5. July 1982||2000||Redesigned computer with program-mable-logic arrays; increased screen resolution to 512 by 256 dots.|
|6. September 1982||2000||Modified design for 5 -inch disk drive|
|7. July 1983||2495||Modified for 3 -inch disk drive|
II. Three generations of personal computers
|Date of introduction||April 1981||January 1983||February 1984|
|Initial price, dollars||15 055||9995||2495|
|Current price, dollars||8995||5995||2195|
|Display resolution, dots||1024 by 808||720 by 364||512 by 342|
 The 68000 microprocessor, which has
exclusive access to the read-only memory of the Macintosh, fetches
commands from ROM at full speed - 7.83 megahertz. The 6800 shares
the random-access memory with the video and sound circuitry, having
access to RAM at an average speed of about 6 megahertz. The video
and sound instructions are loaded directly into the video-shift
register or the sound-counter, respectively. Much of the 'glue'
circuitry of the Macintosh is contained in eight programmable-array-logic
chips. The Macintosh's ability to play four independent voices
was added relatively late in the design, when it was realized
that most of the circuitry needed already existed in the video
circuitry [B]. The four voices are added in software and the
digital samples stored in memory. During the video retrace, sound
data is fed into the sound buffer.