Apple IIGS (styled as IIGS), the fifth and most powerful model of
Apple II family, is a
16-bit personal computer produced by Apple
Computer, Inc. While featuring the
Macintosh look and feel, and
capabilities similar to the Commodore
Amiga and Atari ST, it still
remains backwards compatible with earlier
Apple II models. The "GS" in
the name stands for "Graphics and Sound," referring to its enhanced
multimedia hardware, especially its state of the art audio.
The machine is a radical departure from any previous Apple II, with
16-bit microprocessor, direct access to megabytes of RAM,
and mouse. It was the first computer produced by Apple to use a color
graphical user interface (color was introduced on the
Macintosh II six
months later) and
Apple Desktop Bus
Apple Desktop Bus interface for keyboards, mice, and
other input devices. It is the first personal computer to come with a
built-in wavetable synthesis chip, utilizing technology from Ensoniq.
The IIGS set forth a promising future and evolutionary advancement of
Apple II line, but Apple increasingly focused on the Macintosh
platform. The IIGS clock speed was intentionally kept lower than the
maximum rate possible for the 65C816 so the system would not
outperform the Macintosh. The machine outsold all other Apple
products, including the Macintosh, during its first year in
production. Apple ceased IIGS production in December
1 Hardware features
1.1 Graphics modes
1.2 Audio features
1.3 Expansion capabilities
1.4 Development and codenames
2.1 Limited Edition ("Woz"-signed case)
2.2 Influence on later computers
3 Software features
Apple II compatibility
3.2 System Software
3.2.1 Graphical user interface
3.3 Multitasking capability
4 Upgrading an Apple IIe
6 Technical specifications
6.3 Video modes
6.3.1 Emulation video
6.3.2 Native video
6.6 Internal connectors
6.7 Specialized chip controllers
6.8 External connectors
7 Revision history
7.1 Original firmware release ("ROM version 00")
7.2 Video Graphics Controller (VGC) replacement
7.3 Second firmware release ("ROM version 01")
7.4 Increase standard RAM to 512 KB
7.5 Third firmware release ("ROM version 3"); 1 MB of RAM
8 International versions
11 Rumors and canceled developments
12 Timeline of
Apple II family models
13 See also
15 External links
Apple IIGS made significant improvements over previous machines
from the line such as the
Apple IIe and Apple IIc. It emulates its
predecessors by utilizing a custom chip called the
Mega II and used
Western Design Center 65C816
16-bit microprocessor running at
2.8 MHz, which is faster than the
8-bit NMOS 6502 and CMOS 65C02
processors used in the earlier
Apple II models. Use of the 65C816
allows the IIGS to address considerably more RAM.
The use of a 2.8 MHz clock was a marketing decision intended to
limit the IIGS's performance to a level lower than that of the
Macintosh, a decision that had a critical effect on the IIGS's
success; the 65C816 processor is capable of running at a much
higher clock rate.
The IIGS also includes enhanced graphics and sound, which led to its
GS name. Its graphical capabilities are the best of the Apple II
series, with new higher resolution video modes. These include a
640×200-pixel mode with 2-bit color and a 320×200-pixel mode with
4-bit color, both of which can select 4 or 16 colors (respectively) at
a time from a palette of 4,096 colors. By changing the palette on each
scanline, it is possible to display up to 256 colors or more per
screen, which was quite commonly seen within games and graphic design
software during this computer's heyday. Through some clever
programming, it is possible to make the IIGS display as many as 3,200
colors at once. When first introduced, Apple's user interface known as
MouseDesk and the IIGS System Demo were both in black and white
only. Users did not see color until an application which took
advantage of the new features was launched. Audio is generated by a
built-in sound-and-music synthesizer in the form of the
digital oscillator chip, which has its own dedicated RAM and 32
separate channels of sound. These channels are paired to produce 15
voices in stereo audio.
Although Apple had hoped that the IIc would outsell the IIe, the
latter was more popular because of its slots. The IIGS supports both
5.25-inch and 3.5-inch floppy disks and, like the IIe before it, has
several expansion slots. These include seven general-purpose expansion
slots compatible with those on the Apple II, II+, and IIe, plus a
memory expansion slot that can be used to add up to 8 MB of RAM.
The IIGS, like the IIc, also has dedicated ports for external devices.
These include a port to attach even more floppy disk drives, two
serial ports for devices such as printers and modems (which can also
be used to connect to a
LocalTalk network), an
Apple Desktop Bus
Apple Desktop Bus port
to connect the keyboard and mouse, and composite and RGB video
ports. These ports are associated with the slots, so for example
using a card in slot 1 means that the printer port is disabled. The
machine also features a user-adjustable control panel and real-time
clock, which are maintained by a built-in battery (a non-replaceable
3.6-volt lithium battery; removable in a later revision motherboard).
The IIGS also supports booting from an
AppleShare server, via the
AppleTalk protocol, over
LocalTalk cabling. When the Apple IIe
Workstation Card was introduced, this capability was given to the IIe.
This was over a decade before
NetBoot offered the same capability to
computers running Mac OS 8 and beyond.
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In addition to supporting all graphics modes of previous Apple II
Apple IIGS introduced several new ones through a custom
video graphics chip (VGC), all of which use a 12-bit palette for a
total of 4,096 possible colors, though not all colors can appear
onscreen at the same time.
320×200 pixels with a single palette of 16 colors.
320×200 pixels with up to 16 palettes of 16 colors. In this mode, the
VGC holds 16 separate palettes of 16 colors in its own memory. Each of
the 200 scan lines can be assigned any one of these palettes allowing
for up to 256 colors on the screen at once.
320×200 pixels with up to 200 palettes of 16 colors. In this mode,
the CPU assists the VGC in swapping palettes into and out of the video
memory so that each scan line can have its own palette of 16 colors
allowing for up to 3,200 colors on the screen at once.
320×200 pixels with 15 colors per palette, plus a fill-mode color. In
this mode, color 0 in the palette is replaced by the last non-zero
color pixel displayed on the scan line (to the left), allowing fast
solid-fill graphics (drawn with only the outlines).
640×200 pixels with 4 pure colors.
640×200 pixels with up to 16 palettes of 4 pure colors. In this mode,
the VGC holds 16 separate palettes of 4 pure colors in its own memory.
Each of the 200 scan lines can be assigned any one of these palettes
allowing for up to 64 colors on the screen at once.
640×200 pixels with 16 dithered colors. In this mode, two palettes of
four pure colors each are used in alternating columns. The hardware
then dithers the colors of adjacent pixels to create 16 total colors
on the screen.
Each scan line on the screen can independently select either 320- or
640-line mode, fill mode (320-mode only), and any of the 16 palettes,
allowing graphics modes to be mixed on the screen. This is most often
seen in graphics programs where the menu bar is constantly in
640-pixel resolution and the working area's mode can be changed
depending on the user's needs.
The Apple IIGS's sound is provided by an
Ensoniq 5503 DOC wavetable
synthesis chip designed by Bob Yannes, creator of the SID synthesizer
chip used in the Commodore 64. The ES5503 DOC is the same chip used in
Ensoniq Mirage and
Ensoniq ESQ-1 professional-grade
synthesizers. The chip allows for 32 separate
channels of sound, though most software pairs them into 16 stereo
voices, as do most of the standard tools of the operating system (the
MIDISynth Tool Set groups four channels per voice, for a limit of
seven-voice audio). The IIGS is often referred to as a 15-voice
system, because one stereo voice is reserved by the OS at all times
for timing and system sounds. Software that does not use the OS, or
uses custom-programmed tools (most games and demos do this), can
access the chip directly and take advantage of all 32 voices.
The computer's audio capabilities were given as the primary reason for
record label Apple Corps's 1989 resumption of legal action against
Apple that had been previously suspended.
Apple Corps claimed that the
IIGS's audio chip violated terms of the 1981 settlement with the
company that prohibited Apple, Inc. from getting involved in the music
A standard 1⁄8-inch headphone jack is provided on the back of the
case, and standard stereo computer speakers can be attached there.
However, this jack provides only mono sound, and a third-party adapter
card is required for stereo, despite the fact that the
virtually all native software produces stereo audio (stereo audio is
essentially built into the machine, but has to be de-multiplexed by
third-party cards). Applied Engineering's SonicBlaster is one of a few
developed cards for this purpose.
SCSI expansion card installed in an Apple IIGS
Apple II machines before it, the IIGS is highly expandable.
The expansion slots can be used for a variety of purposes, greatly
increasing the computer's capabilities.
SCSI host adapters can be used
to connect external
SCSI devices such as hard drives and a CD-ROM
drive. Other mass-storage devices such as adapters supporting more
recent internal 2.5-inch IDE hard drives can also be used. Another
common class of
Apple IIGS expansion cards is accelerator cards, such
as Applied Engineering's TransWarp GS, replacing the computer's
original processor with a faster one.
Applied Engineering developed
the PC Transporter, which is essentially an IBM-PC/XT on a card. A
variety of other cards were also produced, including ones allowing new
technologies such as
CompactFlash cards to be
used on the IIGS.
Development and codenames
During the mid-1980s many rumors spread about Steve Wozniak's work on
an "Apple IIx". The IIx was said to have a
16-bit CPU, one megabyte
of RAM, and better graphics and sound. "IIx" was the code name
for Apple's first internal project to develop a next-generation Apple
II based on the 65816. The IIx project, though, became bogged down
when it attempted to include various coprocessors allowing it to
emulate other computer systems. Early samples of the 65816 were also
problematic. These problems led to the cancellation of the IIx
project, but later, a new project was formed to produce an updated
Apple II. This project, which led to the released IIGS, was known by
various codenames while the new system was being developed, including
"Phoenix", "Rambo", "Gumby", and "Cortland". There were rumors of
several vastly enhanced prototypes built over the years at Apple but
none were ever released. Only one, the "Mark Twain", has been revealed
so far. The
Mark Twain prototype (named for Twain's famous quote "The
reports of my death are greatly exaggerated") was expected to have
the "ROM 04" revision (although prototypes that have been discovered
do not contain any new ROM code)  and featured an 8 MHz
65C816, built-in SuperDrive, 2MB RAM, and a hard drive.
Apple IIGS "Woz Edition", with signature on front
During its introduction, Apple sold a specialized set of Bose Roommate
speakers that were platinum-colored with the Apple logo next to the
Bose on each front speaker grille.
Some design features from the unsuccessful
Apple III lived on in the
Apple IIGS, such as GS/OS borrowing elements from SOS (including, by
way of ProDOS, the SOS file system), a unique keyboard feature for
dual-speed arrow keys, and colorized ASCII text.
An easter egg (activated by Command-Option-Control-N) in ROM 3 lists
the members of development team, and plays an audio clip of them
shouting "Apple II!".
Limited Edition ("Woz"-signed case)
As part of a commemorative celebration marking the 10th anniversary of
Apple II series' development, as well as Apple Computer itself
celebrating the same anniversary, a special limited edition was
introduced at product launch. The first 50,000 Apple IIGSs
manufactured had a reproduced copy of Wozniak's signature ("Woz") at
the front right corner of the case, with a dotted line and the phrase
"Limited Edition" printed just below it. Owners of the Limited
Edition, after mailing in their Apple registration card, were mailed
back a certificate of authenticity signed by Wozniak and 12 key Apple
engineers, as well as a personal letter from Wozniak himself (both
machine-reproduced). Because the difference between standard and
Limited Edition machines were purely cosmetic, many owners of new were
able to "convert" to the Limited Edition by merely swapping the case
lid from an older (and likely nonfunctional) machine. While of
nostalgic value to
Apple II users and collectors, presently these
stamped-lid cases are not considered rare, nor do they have any
particular monetary worth.
Influence on later computers
The Apple Desktop Bus, which for a long time was the standard for most
input peripherals for the Macintosh, first appeared on the IIGS. In
addition, the other standardized ports and addition of
SCSI set a
benchmark which allowed, for the first time, Apple to consolidate
their peripheral offerings across both the
Apple II and Macintosh
product lines, permitting one device to be compatible with multiple,
The IIGS is also the first Apple product to bear the new
brand-unifying color scheme, a warm gray color Apple dubbed
"Platinum". This color would remain the Apple standard used on the
vast majority of all products for the next decade. The IIGS is also
the second major computer design after the
Apple IIc by Apple's
outsourced industrial designer
Frogdesign and together with its new
corporate color and matching peripherals, officially ushered in the
Snow White design language
Snow White design language which was used exclusively for the next
five years and made the Apple product line instantly recognizable
around the world.
The inclusion of a professional-grade sound chip in the
Apple IIGS was
hailed by both developers and users, and hopes were high that it would
be added to the Macintosh; however, it drew a lawsuit
from Apple Records. As part of an earlier trademark dispute with the
record company, Apple Computer had agreed not to release music-related
Apple Records considered the inclusion of the
in the IIGS a violation of that agreement.
Software that runs on the
Apple IIGS can be divided into two major
8-bit software compatible with earlier
Apple II systems
such as the IIe and IIc, and
16-bit IIGS software, which takes
advantage of its advanced features, including a near-clone of the
Macintosh graphical user interface.
Apple II compatibility
Apple claimed that the IIGS was 95% compatible with contemporary Apple
II software. One reviewer, for example, successfully ran demo programs
that came on cassette with his 1977 Apple II. The IIGS can run all
of Apple's earlier
Apple II operating systems: Apple DOS,
and Apple Pascal. It is also compatible with nearly all
running on those systems. Like the Apple II+, IIe, and IIc, the IIGS
Applesoft BASIC and a machine-language monitor (which
can be used for very simple assembly language programming) in ROM, so
they can be used even with no operating system loaded from disk. The
8-bit software runs twice as fast unless the user turns down the
processor speed in the IIGS control panel.
Apple IIGS System Software utilizes a graphical user interface
(GUI) very similar to that of the
Macintosh and somewhat like GEM for
PCs and the operating systems of contemporary Atari and Amiga
computers. Initial versions of the System Software are based on the
ProDOS 16 operating system, which is based on the original ProDOS
operating system for
Apple II computers. Although it was
modified so that
Apple IIGS software can run on it,
was written largely in
8-bit code and does not take full advantage of
the IIGS's capabilities. Later System Software versions (starting with
version 4.0) replaced
ProDOS 16 with a new
16-bit operating system
known as GS/OS. It better utilizes the unique capabilities of the IIGS
and includes many valuable new features. The IIGS System Software was
substantially enhanced and expanded over the years during which it was
developed, culminating in its final official version, System 6.0.1,
which was released in 1993. In July 2015, members of an American
computer club released a new version of that System Software, fixing
Graphical user interface
Similar to that of the Macintosh, the IIGS System Software provides a
mouse-driven graphical user interface using concepts such as windows,
menus, and icons. This was implemented by a "toolbox" of code, some of
which resides in the computer's ROM and some of which is loaded from
disk. Only one major application can run at a time, although other,
smaller programs, known as Desk Accessories, can be used
simultaneously. The IIGS has a Finder application very similar to the
Macintosh's, which allows the user to manipulate files and launch
applications. By default, the Finder is displayed when the computer
starts up and whenever the user quits an application that is started
from it, although the startup application can be changed by the user.
Software companies complained that Apple did not provide technical
information and development tools to create IIGS-specific software. In
Compute! reported that both
Cinemaware and Intergalactic
Development had to write their own tools to maximize their use of IIGS
audio, with the latter stating that "these sorts of problems … are
becoming well-known throughout the industry".
The IIGS System Software can be extended through various mechanisms.
Desk Accessories are small programs ranging from a calculator to
simple word processors that can be used while running any standard
desktop application. Classic
Desk Accessories also serve as small
programs available while running other applications, but they use the
text screen and can be accessed even from non-desktop applications.
Control Panels and initialization files are other mechanisms that
allow various functions to be added to the system. Finder Extras
permits new capabilities to be added to the Finder, drivers can be
used to support new hardware devices, and users can also add "tools"
that provide various functions that other programs can utilize easily.
These features can be used to provide features that were never planned
for by the system's designers, such as a TCP/IP stack known as
A third party UNIX-like multitasking kernel was produced, called
GNO/ME, which runs under the GUI and provides preemptive multitasking.
In addition, a system called The Manager can be used to make the
Finder more like the one on the Macintosh, allowing major software
(other than just the "accessory" programs) to run simultaneously
through cooperative multitasking.
Upgrading an Apple IIe
Back view of IIGS upgrade, with the new port openings and connectors
Upon its release in September 1986, Apple announced it would be making
a kit that would upgrade an
Apple IIe to a IIGS available for
purchase. This followed an Apple practice of making logic board
upgrades available that dated from the earliest days of the Apple II
until Steve Jobs' return to Apple in 1997. The IIe-to-IIGS upgrade
replaced the IIe motherboard with a
16-bit IIGS motherboard. Users
would take their
Apple IIe machines into an authorized Apple
dealership, where the IIe motherboard and lower baseboard of the case
were swapped for an
Apple IIGS motherboard with a new baseboard (with
matching cut-outs for the new built-in ports). New metal sticker ID
badges replaced those on the front of the IIe, rebranding the machine.
Retained were the upper half of the IIe case, the keyboard, speaker
and power supply. Original IIGS motherboards (those produced between
1986 and mid-1989) have electrical connections for the IIe power
supply and keyboard present, although only about half of those
produced have the physical plug connectors factory-presoldered in,
which were mostly reserved for the upgrade kits.
The replacement nameplates for the front lid, used in the Apple
The upgrade cost US$500, plus the trade-in of the user's existing
Apple IIe motherboard.
The upgrade proved unpopular for a variety of reasons. Crucially, it
did not include a mouse (which is an essential part of the new
machine, much like the Macintosh), and the keyboard, although
functional, lacked a numeric keypad and did not mimic all the features
and functions of the
Apple Desktop Bus
Apple Desktop Bus keyboard. Additionally, some
cards designed for the new
16-bit machine did not fit in the Apple
IIe's slanted case. In the end, most users found that the upgrade did
not save them much money once they purchased a 3.5-inch floppy drive,
analog RGB monitor, and mouse. Although the IIGS can use some IIe
peripherals, many of them became redundant in the upgrade due to the
new built-in functions of the IIGS. The upgrade was attractive,
however, for some
Apple IIe users wanting to use the machine strictly
in IIe-emulation mode (ignoring the native IIGS nature of the
machine), which provided faster CPU operation, 256 KB RAM, a
clock, and greater connectivity for peripherals via the back ports.
After previewing the computer, BYTE stated in October 1986 that "The
Apple IIGS designers' achievements are remarkable, but the burden of
Apple II architecture, now as venerable (and outdated) as
COBOL and batch processing, may have weighed them down and denied them
any technological leaps beyond an exercise in miniaturization". The
magazine added that "hog-tied by [classic]
Apple II compatibility,
[the IIGS] approaches but does not match or exceed current computer
capabilities" of the Macintosh, Commodore Amiga, or Atari ST, and
predicted that many vendors would "enhance existing products for the
Apple II instead of writing new software" that fully
exploited the IIGS's power.
inCider, which in September had warned that the next
Apple II "needs
(at least) ... a megabyte of RAM ... That's what the market
wants", indeed reported in November that "Rather than risk
investing time and money in programs that work only on the Apple IIGS,
a number of software developers have simply upgraded old Apple II
programs", and that the "most interesting program available
specifically for the IIGS at this time is LearningWays'
Explore-a-Story, which was released simultaneously for the good old
Apple IIe and IIc". The magazine concluded, "The moral is simple:
Good hardware, even innovative hardware, won't give birth to good, new
Nibble was more positive, calling the price "fantastic" for "Steve
Wozniak's dream machine". It praised the IIGS's "incredible" legacy
Apple II compatibility, graphics, and sound, stated that only its
slower speed made the computer significantly inferior to the
Macintosh, and expected that Apple would soon introduce new products
to better distinguish the two product lines. The magazine concluded
that "The IIGS is an incredibly fine computer, arguably the finest
assemblage of chips and resistors ever soldered together ... Ladies
and gentlemen of Apple, on behalf of the
Apple II user community, you
have earned our gratitude and admiration."
Compute! described the IIGS in November 1986 as "two machines in
one—a product that bridges the gap between the
Macintosh and Apple
IIe, and in so doing poses what may be serious competition for the
Amiga and the
Atari ST series". It described the IIGS's
graphics "as different as night and day" from the earlier Apple IIs
and the audio as "in a class by themselves ... [it] justifies the
price of the IIGS to many music fans and fanatics". The magazine
reported that "well over one hundred outside developers were actively
engaged in creating software for the IIGS", and predicted that "as new
products are developed to take advantage of the IIGS, people will move
away from the pure
Apple II software and toward the newer titles with
their improved performance".
Compute!'s Apple Applications in December 1987 reported, however, that
"Many publishers have canceled or postponed their plans for Apple IIGS
software and instead are cautiously introducing programs for the Apple
IIc and IIe", while "many of the products for the
Apple IIGS are
simply versions of" older
Apple II software "that incorporate color
and use the mouse interface". So little IIGS software was available,
it said, that "the hottest product ... is AppleWorks. No mouse
interface, no color, no graphics. Just
AppleWorks from the IIe and IIc
world". The magazine stated that many customers either chose the
slightly more expensive
Macintosh Plus or kept their inexpensive IIc
or IIe which ran
AppleWorks well, with the IIGS "in a strange
position" in between.
Bruce Webster in January 1987 praised Apple for permitting
Wozniak to finish the IIx project, but said that the company should
have done so "a few years ago". The IIGS is an excellent replacement
for the [earlier models from the]
Apple II line, but it's awfully late
in coming. The technology is more trailing-edge than leading-edge in
many areas", with speed and graphics inferior to that of the
Atari ST. The other computers, he wrote, have both larger software
libraries that use their power and lower prices; Webster found that a
IIGS package costing $2500 was comparable to a $1500 Atari ST
configuration. He concluded with a "qualified approval" of the
computer: "It was necessary to prevent the
Apple II line from dying
off during the next year or so. However, Apple didn't go far
enough." A BYTE review in April 1987 concluded that the IIGS "has
the potential to be a powerful computer" but needed a faster CPU and
more addressable memory. The magazine advised potential customers to
compare the Macintosh, Amiga, and Atari ST's more powerful 68000 CPU
with the IIGS's greater expandability and large
Apple II software
Compute! in 1988 urged Apple to make the computer faster, stating that
"no matter which way you cut it, the IIGS is slow" and that
IIGS-specific programs could not keep up with user actions. In
1989 the magazine stated "One of the biggest complaints of
IIGS-specific software is the way it imitates the pace of a zombie.
16-bit software had died and voodoo-transformed into a
shuffling, stumbling imitation of real computer applications." It
reported that year that after increases in September, a IIGS with
color monitor, two disk drives, and
ImageWriter II cost more than
$3,000, a price the magazine called "staggering". inCider also
criticized the price increase, warning that it "opens the door further
to low-cost MS-DOS computers".
WDC 65C816 running at 2.8 MHz
8-bit data bus, with selectable 8- or
4-bit addressing, using a
16-bit address bus and a multiplexed bank
1.125 MB RAM built-in (256 KB in original) (expandable to
256 KB ROM built-in (128 KB in original)
40- and 80-column text, with 24 lines (16 selectable foreground,
background, and border colors)
Low resolution: 40×48 (16 colors)
High resolution: 280×192 (6 colors)
Double low resolution: 80×48 (16 colors)
Double high resolution: 560×192 (16 colors)
Super-high resolution (320 mode)
320×200 (16 colors, selectable from 4,096 color palette)
320×200 (256 colors, selectable from 4,096 color palette)
320×200 (3200 colors, selectable from 4,096 color palette)
Super-high resolution (640 mode)
640×200 (4 colors, selectable from 4,096 color palette)
640×200 (16 colors, selectable from 4,096 color palette)
640×200 (64 colors, selectable from 4,096 color palette)
640×200 (800 colors, selectable from 4,096 color palette)
320×200, sections of screens filled in on-the-fly for up to 60
frame/s full-screen animation
320/640×200, horizontal resolution selectable on a line-by-line basis
Ensoniq 5503 digital oscillator chip
8-bit audio resolution
64 kB dedicated sound RAM
32 oscillator channels (15 voices when paired)
Support for eight independent stereo speaker channels
Apple II Bus slots (50-pin card-edge)
IIGS Memory Expansion slot (44-pin card-edge)
Game I/O socket (16-pin DIP)
Ensoniq I/O expansion connector (7-pin molex)
Specialized chip controllers
IWM (Integrated Woz Machine) for floppy drives
VGC (video graphics controller) for video
Mega II (
Apple IIe computer on chip)
Ensoniq DOC (sample-based synthesis)
Zilog Z8530 SCC (serial port controller)
Apple Desktop Bus
Apple Desktop Bus microcontroller
NTSC composite video output (RCA connector)
Audio-out (1⁄8-inch mono phono jack)
Printer-serial 1 (mini-DIN8)
Modem-serial 2 (mini-DIN8)
Floppy drive (D-19)
Analog RGB video (DA-15)
Apple Desktop Bus
Apple Desktop Bus (mini-DIN4)
While in production between September 1986 and December 1992, the
Apple IIGS remained relatively unchanged from its inception. During
those years, however, Apple did produce some maintenance updates to
the system which mainly comprised two new ROM-based updates and a
revamped motherboard. It is rumored that several prototypes that
greatly enhanced the machine's features and capabilities were designed
and even built, though only one has ever been publicly exposed (i.e.
the "Mark Twain"). Outlined below are only those revisions and updates
officially released by Apple.
Original firmware release ("ROM version 00")
During the entire first year of the machine's production an early,
almost beta-like, firmware version shipped with the machine and was
notably bug-ridden. Some limitation of this include the fact that the
RAM Disk can't be set larger than 4 MB (even if more RAM
is present) and the firmware contains the very early System 1.x
toolsets. It became incompatible with most native
Apple IIGS software
written from late-1987 onward, and OS support only lasted up to System
3. The startup splash screen of the original ROM only displays the
words "Apple IIgs" at the top center of the screen, in the same
fashion that previous
Apple II models identify themselves.
Video Graphics Controller (VGC) replacement
Very early production runs of the machine had a faulty video graphics
controller (VGC) chip that produced strange cosmetic glitches in
emulated (IIe/IIc) video modes. Specifically, the 80-column text
display and monochrome double-high-resolution graphics had a symptom
where small flickering or static pink bits would appear between the
gaps of characters and pixels. Most users noticed this when using
AppleWorks classic or the Mousedesk application that was a part of
System 1 and 2. Apple resolved the issue by offering a free chip-swap
upgrade to affected owners.
Second firmware release ("ROM version 01")
In August 1987, Apple released an updated ROM that was included in all
new machines and was made available as a free upgrade to all existing
owners. The main feature of the new ROM was the presence of the System
2.x toolsets and several bug fixes. The upgrade was vital, as software
developers, including Apple, ceased support of the original ROM upon
its release (most native
Apple IIGS software written from late-1987
onwards would not run unless a ROM 01 or higher was present, and this
included the GS/OS operating system). This update also allows up to
8 MB for the RAM Disk, added some new features for programmers,
and reported the ROM version and copyright information on the startup
Increase standard RAM to 512 KB
In March 1988, Apple began shipping IIGS units with 512 KB of RAM
as standard. This was done by preinstalling the
Apple IIGS Memory
Expansion Card (that was once sold separately) in the memory expansion
slot—the card had 256 KB of RAM on board with empty sockets for
further expansion. The built-in memory on the motherboard remained at
256 KB and existing users were not offered this upgrade.
Third firmware release ("ROM version 3"); 1 MB of RAM
In August 1989, Apple increased the standard amount of RAM shipped in
the IIGS to 1.125 MB. This time the additional memory was
built-in on the motherboard, which required a layout change and
allowed for other minor improvements as well. This update introduced
both a new motherboard and a new ROM firmware update; however, neither
was offered to existing owners—even as an upgrade option (the new
ROM, now two chips, is incompatible with the original single-socket
motherboard). Apple had cited the reason an upgrade was not being
offered was that most of the features of the new machine could be
obtained in existing machines by installing System 5 and a fully
Apple IIGS Memory Expansion Card.
The new ROM firmware then took 256 KB and contained the System
5.x toolsets. The newer toolsets increased the performance of the
machine by up to 10%, due to the fact that less had to be loaded from
disk, tool ROM read access being faster than RAM, and their highly
optimized routines compared to the older toolsets (pre-GS/OS-based).
In addition to several bug fixes, more programmer assistance commands
and features, a cleaned-up control panel with improved mouse control,
RAM Disk functionality, more flexible Appletalk support and
slot-mapping were added.
In terms of hardware, the new motherboard is a cleaner design that
drew less power and resolved audio noise issues that interfered with
Ensoniq synthesizer in the original motherboard. Over four times
more RAM is built-in, with double the ROM size, and an enhanced ADB
microcontroller provides native support for sticky keys, mouse
emulation, and keyboard LED support (available on extended keyboards).
Hardware shadowing of Text Page 2 was introduced, improving
compatibility and performance with the classic
Apple II video mode.
The clock battery is now user-serviceable, being placed in a removable
socket, and a jumper location was added to lock out the text-based
control panel (mainly useful in school environments). Support for the
Apple-IIe-to-IIGS upgrade was removed, and some cost-cutting measures
had some chips soldered in place rather than being socketed. As the
firmware only worked in this motherboard and no new firmware updates
were ever issued, users commonly referred to this version of the IIGS
as the "ROM 3".
Apple IIe and
Apple IIc built-in keyboards before it, the
detached IIGS keyboard differs depending on what region of the world
it was sold in, with extra local language characters and symbols
printed on certain keycaps (e.g. French accented characters on the
Canadian IIGS keyboard such as "à", "é", "ç", etc., or the British
Pound "£" symbol on the UK IIGS keyboard). Unlike previous Apple II
models, however, the layout and shape of keys were the same standard
for all countries, and the ROMs inside the computer were also the same
for all countries, including support for all the different
international keyboards. In order to access the local character set
layout and display, users would change settings in the built-in
software-based control panel, which also provides a method of toggling
between 50/60 Hz video screen refresh. The composite video output
is NTSC-only on all IIGS systems; users in PAL countries are expected
to use an RGB monitor. This selectable internationalization makes it
quick and simple to localize any given machine. Also present in the
settings is a QWERTY/DVORAK keyboard toggle for all countries, much
like that of the Apple IIc. Outside North America, the Apple IIGS
shipped with a different 220 V clip-in power supply, making this
and the plastic keycaps the only physical differences (and also very
modular, in the sense of converting a non-localized machine to a local
Apple designed the
Apple IIe Card to transit
Apple IIe customers to
Macintosh LC, particularly schools who had a large investment in
Apple II software. While Apple discussed creating an LC plug-in IIGS
card, they felt that the cost of selling it would be as much as an
entire LC and abandoned it. However, the educational community had
a substantial investment in the IIGS software as well, which made
upgrading to a
Macintosh a less attractive proposition than had been
for the Apple IIe. As a result, Apple software designers Dave Lyons
and Andy Nicholas spearheaded a program to develop a IIGS software
emulator they called Gus in their spare time, which would run on the
Macintosh only. Apple did not officially support the
project. Nevertheless, seeing the need to help switch their
educational customers to the
Macintosh (as well as sell Power Macs),
Apple unofficially distributed the software for free to schools and
other institutions that signed a non-disclosure agreement.
It was never offered for public sale, but is now readily available on
the internet, along with many third-party classic
Apple II emulators.
Gus represents one of the few software emulators developed within
Apple (officially or otherwise), including MacWorks and Mac OS X
John Carmack, co-founder of id Software, started his career by writing
commercial software for the Apple IIGS, working with
John Romero and
Tom Hall. Wolfenstein 3D, based on the 1981
Apple II game Castle
Wolfenstein, came full-circle when it was released for the Apple IIGS
Two mainstream video games,
Zany Golf and The Immortal, both designed
by Will Harvey, originated as
Apple IIGS games that were ported to
other platforms, including the Sega Genesis.
Pangea Software started as an
Apple IIGS game developer. Naughty Dog
started with the classic
Apple II machines, but later developed for
Rumors and canceled developments
In August 1988, inCider magazine reported Apple was working on a new
Apple IIGS. It was stated it had a faster CPU, improved graphics
(double the vertical resolution, 256 colors per scanline and 4,096
colors per screen), 768k RAM, 256k ROM, 128K sound DOC-RAM and a
SCSI port. No new machine would appear that year.
Compute! reported on speculation that Apple would announce at
the May AppleFest a "IIGS Plus" with a processor two to three times
faster, 768KB to 1MB RAM, and
SCSI port. The speculation was
partially based on Apple CEO
John Sculley stating that the IIGS would
receive a new CPU in 1989. No new computer appeared, but in
August the IIGS started shipping with 1MB RAM in the base
VTech, makers of the
8-bit Apple II-compatible Laser 128, announced
plans for a IIGS-compatible computer in 1988 for under $600. They
demonstrated a prototype in 1989, but the computer was never
Cirtech started work on, but never completed, a black-and-white
Macintosh hardware emulation plug-in card for the IIGS dubbed "Duet".
Using a 68020 processor, custom ROM and up to 8 MB RAM, Cirtech
claimed it would outperform the
Apple II family models
See also: Timeline of the
Apple II family
See also: Timeline of
Macintosh models and Timeline of Apple Inc.
Apple IIc Plus
Juiced.GS, the last
Apple II publication
KansasFest, an annual convention for
Apple II users
Apple IIGS games
^ Electronic and computer music By Peter Manning.
^ a b Histoire de l'Apple IIGS, "Histoire de l'Apple IIGS"
^ Kavadias, Tony (July 24, 2004). "
Apple II User Interfaces".
Guidebookgallery.org. Retrieved November 13, 2011.
^ a b c Williams, Gregg; Grehan, Richard (October 1986). "The Apple
IIGS". BYTE. p. 84. Retrieved 4 November 2013.
^ a b c Chien, Philip (April 1987). "The Apple IIGS". BYTE.
p. 223. Retrieved 5 November 2013.
^ Pournelle, Jerry (March 1985). "On the Road: Hackercon and COMDEX".
BYTE. p. 313. Retrieved 19 March 2016.
^ Statt, Paul (August 1986). "Future II's". inCider. p. 14.
Retrieved 10 August 2014.
^ de Peyster, Deborah; Statt, Paul (September 1986). "Extras for the
//x". inCider. p. 14. Retrieved 2 July 2014.
Apple II Guide and Mark Twain".
^ "Apple IIGS".
^ "OLD-COMPUTERS.com Museum".
^ The original
Apple II FAQ, the Apple IIGS
^ Schwan, Ben (July 20, 2015). "System 6.0.2 für den Apple IIgs
erscheint nach 22 Jahren". Heise Online. Retrieved June 8, 2016.
^ Keizer, Gregg (December 1988). "Where's Apple?". Compute!.
p. 64. Retrieved 10 November 2013.
^ Statt, Paul (September 1986). "Stattus Report". inCider.
p. 110. Retrieved 2 July 2014.
^ Statt, Paul (November 1986). "Visions of GS Software". inCider.
p. 46. Retrieved 1 July 2014.
^ Szetela, David (October 1986). "The New II". Nibble. p. 5.
Retrieved 18 August 2014.
^ Thornburg, David D. (November 1986). "The New Apple IIGS". Compute!.
p. 18. Retrieved 4 July 2014.
^ "II On II". Compute!'s Apple Applications. December 1987. p. 8.
Retrieved 18 August 2014.
^ Webster, Bruce (January 1987). "View and Reviews". BYTE.
p. 367. Retrieved 30 June 2014.
^ Keizer, Gregg (November 1988). "IIGS Gets Going". Compute!.
p. 66. Retrieved 10 November 2013.
^ Keizer, Gregg (March 1989). "Apple II". Compute!. p. 58.
Retrieved 10 November 2013.
^ Keizer, Gregg (February 1989). "Stratospheric". Compute!.
p. 50. Retrieved 10 November 2013.
^ Muse, Dan (November 1988). "Born Old (But Not Ugly)". inCider.
p. 8. Retrieved 1 July 2014.
^ Effectively 140×192 in color, due to pixel placement restrictions.
^ a b Text can be mixed with graphic modes, replacing either bottom 8
or 32 lines of graphics with four lines of text, depending on video
mode. Colorized text is unique to the Apple IIGS, all other Apple II
models produce text in only black and white.
^ a b c d 16 colors per scanline, palette can be changed on each line.
Exceeding 16 palettes per screen drastically limits system resources
(e.g. only useful for static images typically).
^ Dithered mode creates the visual illusion of 16 colors by alternated
colored pixels in the 4 mini palettes, in addition to taking advantage
of the AppleColor RGB's high (0.37 mm) dot pitch.
^ Only 15 voices are available in most software due to firmware
pairing oscillators and reserving one for timing.
^ a b While output from audio jack is mono, and all third-party stereo
cards only produce two-channel stereo, the capability for supporting
8-channel stereo is present on the motherboard/chip.
^ "apple2history.org, The Apple IIGS, The Beginning of the End".
Apple2history.org. September 25, 1991. Retrieved March 27, 2017.
Apple II – Rumors, Facts and Fables – Part 2".
Apple2.org.za. September 15, 1996. Retrieved November 13, 2011.
^ "kashum.com, Me and the Apple II". Kashum.com. Retrieved November
^ "apple2history.org, Museum, Screenshots: "Gus Emulator"".
Apple2history.org. Retrieved November 13, 2011.
^ "scout.wisc.edu, Run
Apple IIGS programs on your Mac".
Scout.wisc.edu. April 2, 1997. Retrieved November 13, 2011.
^ "wap.org, Washington Apple Pi's
Apple II Page". Wap.org. Retrieved
November 13, 2011.
^ "emulation.victoly.com, Apple II, Gus 1.0b4". Web.archive.org.
September 29, 2007. Archived from the original on September 29, 2007.
Retrieved November 13, 2011.
^ "www.apple2.nu, GenieLamp
Apple II Vol.5, Issue 53, MESSAGE
SPOTLIGHT: A few words about Gus:". Retrieved November 13, 2011.
^ "The Giant List of Classic Game Programmers". dadgum.com.
^ Keizer, Gregg (February 1989). "Talk, Talk, Talk". Compute!.
p. 51. Retrieved 10 November 2013.
^ Keizer, Gregg (July 1989). "
Apple II Forever?". Compute!.
p. 55. Retrieved 11 November 2013.
^ a b Keizer, Gregg (August 1989). "No IIGS Plus". 1989-08.
p. 54. Retrieved 11 November 2013.
^ Ferrell, Keith (April 1988). "Computers Win Big!". Compute!.
p. 6. Retrieved 10 November 2013.
Wikimedia Commons has media related to Apple IIGS.
"The New Apple IIGS" from
Compute! magazine (November 1986)
Apple II History from Steven Weyhrich
What is the Apple IIGS, reviews of many
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Apple hardware before 1998
Apple II series
LC 500 series
4400 and 7220
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6200 and 6300
7200 and 8200
Apple IIe Card (
Apple Workgroup Server
Apple Network Server
Twentieth Anniversary Macintosh
AppleColor Composite IIe
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Multiple Scan 14
Hard Disk 20
Hard Disk 20SC
Tape Drive 40SC
Apple II serial cards
Apple Communication Slot
Dot Matrix Printer
Letter Quality Printer
410 Color Plotter
Interactive Television Box