Apple II (stylized as Apple ][) is an
8-bit home computer, one of
the first highly successful mass-produced microcomputer products,
designed primarily by
Steve Wozniak (
Steve Jobs oversaw the
development of the Apple II's foam-molded plastic case and Rod Holt
developed the switching power supply). It was introduced in 1977 at
West Coast Computer Faire
West Coast Computer Faire by Jobs and was the first consumer
product sold by Apple Computer, Inc. It is the first model in a series
of computers which were produced until
Apple IIe production ceased in
November 1993. The
Apple II marks Apple's first launch of a
personal computer aimed at a consumer market – branded towards
American households rather than businessmen or computer hobbyists.
Along with the PET 2001 and the TRS-80, Byte magazine referred to
these as the "1977 Trinity" of personal computing. The
Apple II had
the defining feature of being able to display color graphics, and this
capability was the reason why the
Apple logo was redesigned to have a
spectrum of colors.
2.1 Innovation of integrated user interface
3 Case design
4 PCB revisions
5 Display and graphics
8 Third-party devices and applications
10 In popular culture
11 See also
13 External links
Steve Jobs had convinced the product designer Jerry Manock
(who had formerly worked at Hewlett Packard designing calculators) to
create the "shell" for the
Apple II – a smooth case inspired by
kitchen appliances that would conceal the internal mechanics. The
earliest Apple IIs were assembled in Silicon Valley, and later in
Texas; printed circuit boards were manufactured in
Singapore. The first computers went on sale on June 10, 1977
MOS Technology 6502
MOS Technology 6502 microprocessor running at 1.023 MHz,
two game paddles (no longer bundled as of 1980 because they
violated FCC regulations), 4 KB of RAM, an audio cassette
interface for loading programs and storing data, and the Integer BASIC
programming language built into the ROMs. The video controller
displays 24 lines by 40 columns of monochrome, upper-case-only (the
original character set matches ASCII characters 20h to 5Fh) text on
the screen, with
NTSC composite video output suitable for display on a
TV monitor, or on a regular TV set by way of a separate RF modulator.
The original retail price of the computer was $1,298 (with
4 KB of RAM) and $2,638 (with the maximum 48 KB of RAM).
To reflect the computer's color graphics capability, the
Apple logo on
the casing has rainbow stripes, which remained a part of Apple's
corporate logo until early 1998. Perhaps most significantly, the Apple
II was a catalyst for personal computers across many industries; it
was responsible for opening the doors to software marketed at
In the May 1977 issue of Byte,
Steve Wozniak published a detailed
description of his design; the article began, "To me, a personal
computer should be small, reliable, convenient to use and
Apple II used a multiplicity of idiosyncratic engineering
shortcuts to save hardware and reduce costs. For example:
Taking advantage of the way that 6502 processor only accesses memory
on alternate phases of the clock cycle, the video generation
circuitry's memory access on the otherwise unused phase avoids memory
contention issues and interruptions of the video stream.
This arrangement simultaneously eliminated the need for a separate
refresh circuit for the
DRAM chips, as the video transfer accessed
each row of the dynamic memory within the timeout period.
Rather than use a complex analog-to-digital circuit to read the
outputs of the game controller, Wozniak used a simple timer circuit
whose period is proportional to the resistance of the game controller,
and used a software loop to measure the timer.
A single 7
MHz master oscillator was divided by various ratios to
produce all other required frequencies, including the microprocessor
clock signals, the video transfer counters, and the color-burst
The text and graphics screens have a complex arrangement (the
scanlines were not stored in sequential areas of memory) which is
reputedly due to Wozniak's realization that doing it that way would
allow for the refresh of the dynamic RAM as a side effect, as
described above; it had no cost overhead to have software calculate or
look up the address of the required scanline and avoided the need for
significant extra hardware. Similarly, in the high-resolution graphics
mode, color is determined by pixel position and can thus be
implemented in software, saving Wozniak the chips needed to convert
bit patterns to colors. This also allows for subpixel font rendering
since orange and blue pixels appear half a pixel-width farther to the
right on the screen than green and purple pixels.
Apple II at first used data cassette storage like most other
microcomputers of the time. In 1978, the company introduced an
external 5 1⁄4-inch floppy disk drive, the Disk II, attached
via a controller card that plugs into one of the computer's expansion
slots (usually slot 6). The
Disk II interface, created by Wozniak, is
regarded as an engineering masterpiece for its economy of electronic
The approach taken in the
Disk II controller is typical of Wozniak's
designs. With a few small-scale logic chips and a cheap PROM
(programmable read-only memory), he created a functional floppy-disk
interface at a fraction of the component cost of standard circuit
Innovation of integrated user interface
Apple I and the Apple II, Wozniak introduced an entirely
novel configuration of the microcomputer concept which was immediately
adopted as the industry standard, and remains taken for granted to
this day—namely the integration of the standard input and output
devices (the typewriter-style keyboard and the video display screen)
into the computer itself. Until that time, microcomputer devices
either had an extremely limited I/O capability—such as perhaps a hex
keypad and a 16- or 32-character display, or no built-in user
interface at all, following the convention of mainframe and
minicomputers in requiring the connection of an external teleprinter
unit or visual display terminal to complete a usable system. The cost
of such terminals could easily exceed the price of the computer
itself. Wozniak's inclusion of an RF output which could connect to the
aerial socket of a standard domestic television set enabled users to
acquire a complete system without incurring the cost of a video
Steve Jobs extensively pushed to give the
Apple II a case that looked
visually appealing and sellable to people outside of electronics
hobbyists, rather than the generic wood and metal boxes typical of
early microcomputers. The result was a futuristic-looking molded white
plastic case. Jobs also payed close attention to the keyboard design
and decided to use dark brown keycaps as it contrasted well with the
The first production Apple IIs had hand-molded cases; these had
visible bubbles and other lumps in them from the imperfect plastic
molding process, this was soon switched to machine molding. In
addition, the initial case design had no vent openings, causing high
heat buildup from the PCB and resulting in the plastic softening and
sagging. Apple added vent holes to the case within three months of
production; customers with the original case could have them replaced
at no charge.
The Apple II's PCB underwent several revisions as
Steve Wozniak made
modifications to it. The earliest version was known as Revision 0, and
the first 6,000 units shipped used it. Later revisions added a color
killer circuit to prevent color fringing when the computer was in text
mode, as well as modifications to improve the reliability of cassette
I/O. Revision 0 Apple IIs powered up in an undefined mode and had
garbage on-screen, requiring the user to press Reset. This was
eliminated on the later board revisions. Revision 0 Apple IIs could
display only four colors, but Wozniak was later able to generate 16 in
Original Apple IIs were designed to accommodate either 2104 (4kx1)
DRAM or 4116 (16kx1)
DRAM and had jumper switches to adjust the RAM
size. The early Apple II+ models retained this feature, but after a
DRAM prices, Apple redesigned the circuit boards without the
jumpers so that only 16k chips were supported. A few months later they
started shipping all machines with a full 48 KB complement of
Display and graphics
Apple II graphics
Color on the
Apple II series
Apple II series uses a quirk of the
signal standard, which made color display relatively easy and
inexpensive to implement. The original
NTSC television signal
specification was black-and-white. Color was added on later by adding
MHz subcarrier signal that was partially ignored by
black-and-white TV sets. Color is encoded based on the phase of this
signal in relation to a reference color burst signal. The result is
that the position, size, and intensity of a series of pulses define
color information. These pulses can translate into pixels on the
computer screen, with the possibility of exploiting composite artifact
Apple II display provides two pixels per subcarrier cycle. When
the color burst reference signal is turned on and the computer
attached to a color display, it can display green by showing one
alternating pattern of pixels, magenta with an opposite pattern of
alternating pixels, and white by placing two pixels next to each
other. Blue and orange are available by tweaking the offset of the
pixels by half a pixel-width in relation to the color-burst signal.
The high-resolution display offers more colors by compressing more
(and narrower) pixels into each subcarrier cycle.
The coarse, low-resolution graphics display mode works differently, as
it can output a pattern of dots per pixel to offer more color options.
These patterns are stored in the character generator ROM and replace
the text character bit patterns when the computer is switched to
low-res graphics mode. The text mode and low-res graphics mode use the
same memory region and the same circuitry is used for both.
Rather than a dedicated sound-synthesis chip, the
Apple II has a
toggle circuit that can only emit a click through a built-in speaker
or a line out jack; all other sounds (including two-, three- and,
eventually, four-voice music and playback of audio samples and speech
synthesis) are generated entirely by software that clicked the speaker
at just the right times. Similar techniques are used for cassette
storage: the cassette output works the same as the speaker, and the
input is a simple zero-crossing detector that serves as a relatively
crude (1-bit) audio digitizer. Routines in the ROM encode and decode
data in frequency-shift keying for the cassette.
Apple II was shipped with
Integer BASIC encoded in the
motherboard ROM chips. Written by Wozniak, the interpreter enabled
users to write software applications without needing to purchase
additional development utilities. Written with game programmers and
hobbyists in mind, the language only supported the encoding of numbers
in 16-bit integer format. But limiting numerical values to whole
numbers between -32768 and +32767 reduced the machine's attractiveness
to business users. Jobs responded by licensing a floating-point
version of BASIC from Microsoft which was initially available as a
plug-in expansion card. Named Applesoft BASIC, this more versatile
(but slower) variant was more popular with customers, so later models
were shipped with it as standard. Models with
Applesoft BASIC in ROM
and the optional "Language Card" installed could load Integer BASIC
from disk if needed.
As shipped, the machine incorporated a "monitor" program which
supported functions such as displaying and altering the contents of
the computer's RAM memory in hexadecimal format, either one byte at a
time or in blocks of 256 bytes at once. This feature enabled hackers
to write and debug machine code programs without needing further
A 6502 assembler was soon offered on disk, and later the
and operating system for the Pascal language were made available. The
Pascal system required a 16 KB RAM card to be installed in the
language card position (expansion slot 0) in addition to the full
48 KB of motherboard memory.
Third-party devices and applications
Wozniak's open-architecture design and the Apple II's multiple
expansion slots permit a wide variety of third-party devices,
including peripheral cards such as serial controllers, display
controllers, memory boards, hard disks, networking components, and
realtime clocks. There are plug-in expansion cards – such as the
Z-80 SoftCard – that permit the Apple to use the Z80 processor and
run programs for the
CP/M operating system, including the dBase II
database and the
WordStar word processor. The Z80 card also allows the
connection to a modem and thereby to any networks that the user might
have access to. In the early days, these were scarce, but expanded
significantly with the development of bulletin board systems. There is
also a third-party 6809 card that allows
OS-9 Level One to be run.
Third-party sound cards greatly improve audio capabilities, allowing
simple music synthesis and text-to-speech functions. Apple II
accelerator cards double or quadruple the computer's speed.
Advertisement for the
Apple II (1977)
Jesse Adams Stein wrote, "As the first company to release a 'consumer
appliance' micro-computer, Apple Computer offers us a clear view of
this shift from a machine to an appliance." But the company also had
"to negotiate the attitudes of its potential buyers, bearing in mind
social anxieties about the uptake of new technologies in multiple
contexts. The office, the home and the 'office-in-the-home' were
implicated in these changing spheres of gender stereotypes and
technological development." After seeing a crude, wire-wrapped
prototype demonstrated by Wozniak and
Steve Jobs in November 1976,
Byte predicted in April 1977 that the
Apple II "may be the first
product to fully qualify as the 'appliance computer' ... a completed
system which is purchased off the retail shelf, taken home, plugged in
and used". The computer's color graphics capability especially
impressed the magazine. The magazine published a favorable review
of the computer in March 1978, concluding, "For the user that wants
color graphics, the
Apple II is the only practical choice available in
the 'appliance' computer class".
Personal Computer World
Personal Computer World in August 1978 also cited the color capability
as a strength, stating that "the prime reason that anyone buys an
Apple II must surely be for the colour graphics". While mentioning the
"oddity" of the artifact colors that produced output "that is not
always what one wishes to do", it noted that "no-one has colour
graphics like this at this sort of price". The magazine praised the
sophisticated monitor software, user expandability, and comprehensive
documentation, and concluded that "the
Apple II is a very promising
machine" which "would be even more of a temptation were its price
slightly lower ... for the moment, colour is an Apple II".
Although it sold well from the launch, the initial market was to
hobbyists, games players and computer enthusiasts. Sales expanded
exponentially into the business and professional market when the
VisiCalc was launched in mid-1979.
credited as being the defining "killer app" in the microcomputer
During the first five years of operations, revenues doubled about
every four months. Between September 1977 and September 1980, yearly
sales grew from $775,000 to $118 million. During this period the
sole products of the company were the
Apple II and its peripherals,
accessories and software.
In popular culture
In 2017, the band
8 Bit Weapon
8 Bit Weapon released the world's first 100% Apple
II-based music album entitled Class Apples. The album features
dance-oriented cover versions of classical music by Bach, Beethoven,
and Mozart recorded directly from the
Apple II motherboard.
Computer science portal
^ "Musée Bolo". École Polytechnique Fédérale de Lausanne.
Retrieved October 23, 2011.
^ Steven Weyhrich (2010-07-10). "1969-1977".
Apple II History.
^ a b Steven Weyhrich (May 16, 2003). "1990-1995".
Apple II History.
Retrieved May 25, 2010.
^ Reimer, Jeremy (December 14, 2005). "Total share: 30 years of
personal computer market share figures". Ars Technica. Retrieved May
^ Isaacson, Walter (2011). Steve Jobs. Simon & Schuster.
^ Wozniak, Steve. "woz.org: Comment From e-mail: Why didn't the early
Apple II's use Fans?". woz.org. Retrieved 2015-05-10.
^ a b c Stein, Jesse Adams (2011). "Domesticity, Gender and the 1977
Apple II Personal Computer". Design and Culture. 3 (2).
^ "Most Important Companies". Byte. September 1995. Archived from the
original on 2008-06-18. Retrieved 2008-06-10.
^ Rose, Frank (1989). West of Eden. Arrow Books. p. 3.
^ "June 10, 1977 -
Apple II Released Today". This Day in History.
Mountain View, CA: Computer History Museum. Retrieved August 3,
2012. June 10, 1977 was a Friday.
^ Weyhrich, Steven. "4-The Apple II, cont. - Product Introduction".
Apple II History. Apple2History.org. Retrieved August 3, 2012. The
Apple II computers shipped on May 10, 1977, for
those who wanted to add their own case, keyboard, and power supply (or
wanted to update their Apple-1 'system' with the latest and greatest).
A month later, on June 10, 1977, Apple began shipping full Apple II
^ a b c Helmers, Carl (March 1978). "An Apple to Byte". BYTE.
p. 18. Retrieved October 17, 2013.
^ Ahl, David H.; Rost, Randi J. (1983), "Blisters And Frustration:
Joysticks, Paddles, Buttons and Game Port Extenders for Apple, Atari
and VIC", Creative Computing Video & Arcade Games, 1 (1):
^ Forster, Winnie (2005). The encyclopedia of consoles, handhelds
& home computers 1972 – 2005. GAMEPLAN. p. 19.
Apple II price list A-VIDD Electronics Co., 1977 Long Beach,
^ Steven Weyhrich (April 21, 2002). "4-The Apple II, cont". Apple II
History. Archived from the original on September 25, 2006. Retrieved
November 16, 2006.
^ Wozniak, Steve (May 1977). "System Description / The Apple-II".
BYTE. pp. 34–43. Retrieved October 17, 2013.
^ Gibson, Steve. "The origins of sub-pixel font rendering". Gibson
Research Corporation. Archived from the original on July 21, 2006.
Retrieved August 4, 2006.
^ Steven Weyhrich (December 28, 2001). "5-The Disk II". Apple II
History. Archived from the original on December 1, 2006. Retrieved
November 16, 2006.
^ Freiberger, Paul; Swaine, Michael (January 1985). Fire In The
Valley, Part Two. A+ Magazine (Book excerpt). p. 45.
^ Petersen, Marty (February 6, 1984). "Review: Premium Softcard IIe".
InfoWorld Media Group (Vol. 6, Num. 6): 64. Several
manufacturers, however, make Z80 coprocessor boards that plug into the
^ Stein, Jesse Adams, "In Memoriam: Domesticity, Gender and the 1977
Apple II Personal Computer," Design and Culture 3:2 (2011), 194.
^ Helmers, Carl (April 1977). "A Nybble on the Apple". BYTE.
p. 10. Retrieved October 16, 2013.
^ Coll, John; Sweeten, Charles (August 1978). "Colour is an Apple II".
Personal Computer World. p. 50. Retrieved 18 August 2014.
^ Infinite Loop, Malone, p157
Apple II Album Released!". 8 Bit Weapon. 2017-07-22.
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