Apple IIGS

Apple IIGS

Apple IIGS
Release date September 1986
Introductory price US$999
Discontinued December 1992
Operating system Apple ProDOS,
Apple GS/OS
CPU 65C816
Memory 256 kB or 1 MB (expandable up to 8 MB)
Graphics VGC 12-bpp palette, 320×200, 640×200
Sound Ensoniq ES5503 DOC 8-bit sample-based sound chip, 32-channels, stereo

The Apple IIGS (styled as IIGS) is the fifth and most powerful model in the Apple II series of personal computers produced by Apple Computer. The "GS" in the name stands for Graphics and Sound, referring to its enhanced multimedia capabilities, especially its state-of-the-art sound and music synthesis, which greatly surpassed previous models of the line and most contemporary machines like the Macintosh and IBM PC.[1]

The machine was a radical departure from any previous Apple II, with its true 16-bit architecture, increased processing speed, direct access to megabytes of RAM, sample-based music synthesizer, graphical user interface, and mouse. While still maintaining full backwards compatibility with earlier Apple II models, it blended the Apple II and aspects of Macintosh technology into one. Keeping with Apple's "Apple II Forever" slogan of the time, the IIGS set forth a promising future and evolutionary advancement of the Apple II line, but Apple paid it relatively little attention as the company increasingly focused on the Macintosh platform.

The Apple IIGS was the first computer produced by Apple to use a color graphical user interface, as well as the "Platinum" (light grey) color scheme and the Apple Desktop Bus interface for keyboards, mice, and other input devices. It was also the first personal computer to come with a built-in sample-based synthesizer chip (erroneously marketed as a "wavetable synthesizer"[2]), utilizing technology from Ensoniq. The machine outsold all other Apple products, including the Macintosh, during its first year in production.


  • Background 1
  • Hardware features 2
    • Graphics modes 2.1
    • Audio features 2.2
    • Expansion capabilities 2.3
    • Development and codenames 2.4
  • Release 3
    • Limited Edition ("Woz" signed case) 3.1
    • Influence on later computers 3.2
  • Software features 4
    • 8-bit Apple II compatibility 4.1
    • Apple IIGS System Software 4.2
      • Graphical user interface 4.2.1
      • Extensibility 4.2.2
    • Multitasking capability 4.3
  • Upgrading from an Apple IIe 5
  • Reception 6
  • Technical specifications 7
    • Microprocessor 7.1
    • Memory 7.2
    • Video modes 7.3
      • Emulation video 7.3.1
      • Native video 7.3.2
    • Audio 7.4
    • Expansion 7.5
    • Internal connectors 7.6
    • Specialized chip controllers 7.7
    • External connectors 7.8
  • Revision history 8
    • Original firmware release ("ROM version 00") 8.1
    • Video Graphics Controller (VGC) replacement 8.2
    • Second firmware release ("ROM version 01") 8.3
    • Increase standard RAM to 512 KB 8.4
    • Third firmware release ("ROM version 3"), The Apple IIGS with 1 MB of RAM 8.5
  • International versions 9
  • Gus 10
  • Apple IIGS developers 11
  • Canceled developments 12
  • Timeline of Apple II family models 13
  • See also 14
  • References 15
  • External links 16


The IIGS was released September 15, 1986. Apple's portion of the computer industry at this time was transitioning from the 8-bit 6502 CPU technology that started it, to the newer 16/32 bit Motorola 68000 used by computers such as the Commodore Amiga and Atari ST and the Apple Macintosh. In order to maintain compatibility with previous members of the Apple II line, Apple used the Western Design Center 65C816 processor. In addition to providing platform continuity, the lower-capability processor kept the IIGS from competing with the Macintosh which, at the time, was monochrome-only.

Like the Apple IIe, the IIGS was popular with schools, but Apple failed to promote and update the computer, preferring to focus on introducing the Macintosh into these markets instead. The IIGS was far more expensively priced and slower in terms of raw processing speed compared to its competitors and increasingly, without regular advancement updates, fell behind other personal computers over its lifetime. Apple finally ceased production of the model in December 1992.

Hardware features

The Apple IIGS was an innovative computer with many improvements over the older Apple IIe and Apple IIc. It emulated its predecessors by utilizing a custom chip called the Mega II and used the new Western Design Center 65C816 16-bit microprocessor running at 2.8  MHz, which was faster than the 8-bit NMOS 6502 and CMOS 65C02 processors used in earlier Apple II models. Use of the 65C816 allowed the IIGS to address considerably more RAM.

The use of a 2.8 MHz clock was a marketing decision intended to limit the IIgs' performance to a level lower than that of the Macintosh, a decision that had a critical effect on the Apple IIgs' success.[3] In actuality, the 65C816 processor was capable of running at a much higher clock rate.

The IIGS also included enhanced graphics and sound, which led to its GS name. Its graphics were the best of the Apple II series, with new Super High Resolution video modes. These included a 640×200-pixel mode with 2-bit color and a 320×200-pixel mode with 4-bit color, both of which could select 4 or 16 colors (respectively) from a palette of 4,096 colors. By changing the palette on each scanline, it was possible to display up to 256 colors or more per screen, which was quite commonly seen within games and graphic design software. Through some clever programming, it was possible to 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.[4] Users did not see color until an application which took advantage of the new features was launched. Audio was generated by a built-in sound and music synthesizer in the form of the Ensoniq 5503 Digital Oscillator Chip (DOC), which had its own dedicated RAM and 32 separate channels of sound. These channels were paired to produce 15 voices, in stereo audio.[5]

Although Apple had hoped that the Apple IIc would outsell the IIe, the latter was more popular because of its slots. The IIGS could support both 5.25-inch and 3.5-inch floppy disks and, like the IIe before it, had several expansion slots. These included seven general-purpose expansion slots compatible with those on the Apple II, II+, and IIe, plus a memory expansion slot that could be used to add up to 8 MB of RAM. The IIGS, like the IIc, also had dedicated ports for external devices. These included a port to attach floppy disk drives, two serial ports for devices such as printers and modems (which could also be used to connect to a LocalTalk network), an Apple Desktop Bus port to connect the keyboard and mouse, and composite and RGB video ports.[5] These ports were associated with the slots, so for example using a card in slot 1 would mean the printer port was disabled. The machine also featured a user adjustable Control Panel and real-time clock, which were maintained by a built-in battery (a non-replaceable 3.6 volt Lithium battery; removable in a later revision motherboard).

The IIGS also supported 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.

Graphics modes

In addition to supporting all graphics modes of previous Apple II models, the Apple IIGS introduced several new ones through a custom Video Graphics Chip (VGC), all of which used a 12-bit palette for a total of 4,096 possible colors, though not all colors could 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. This mode is handled entirely by the VGC with no CPU assistance, making it perfect for games and high-speed animation.
  • 320×200 pixels with up to 200 palettes of 16 colors. In this mode, the CPU assists the VGC in swapping palettes in 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. This mode is computationally intensive, however, and is only suitable for viewing graphics or in paint programs.
  • 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 four pure colors. This mode is generally only used for ensuring that the Apple logo and menu bar retain their colors in Desktop applications.
  • 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. This mode is generally used for programs requiring finer detail such as word processors and the Finder.

Each scan line on the screen could independently select either 320- or 640-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.

Like other Apple computers, the IIGS lacked hardware sprites.

Later on, video cards such as Sequential Systems' Second Sight added SVGA modes allowing 24-bit color to the Apple IIGS.

Audio features

The Apple IIGS sound is provided by an Ensoniq 5503 DOC sample-based synthesis sound 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 fifteen-voice system, because one stereo voice is reserved by the OS at all times for timing and system sounds. Software that doesn't 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 audio chip violated terms of the 1981 settlement with the company that prohibited Apple, Inc. from getting involved in the music business.

A standard 18-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,[6] despite the fact that the Ensoniq and 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.

Expansion capabilities

An Apple SCSI expansion card installed in an Apple IIGS.

Like the Apple IIe before it, the IIGS was highly expandable. The expansion slots could be used for a variety of purposes, greatly increasing the computer's capabilities. SCSI host adaptors could be used to connect external SCSI devices such as hard drives and CD-ROM drives. Other mass storage devices such as adaptors supporting more recent internal 2.5-inch IDE hard drives could also be used. Another common class of Apple IIGS expansion cards was 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 was essentially an IBM-PC/XT on a card. A variety of other cards were also produced, including ones allowing new technologies such as 10BASE-T Ethernet and CompactFlash cards to be used on the IIGS.

Development and codenames

Before its release the IIGS was called the "IIx", rumored to have a 16-bit CPU, one megabyte of RAM, and better graphics and sound.[7][8] The 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")[9] used ROM 04[10] and featured an 8 MHz 65C816, built-in Superdrive, 2MB RAM, and a hard drive.[11]


An original 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 filesystem), 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 the 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 IIGS's manufactured had a reproduced copy of Steve 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 Steve Wozniak himself (both machine reproduced). Seeing as the difference between standard and Limited Edition machines were purely cosmetic, many users were able to "convert" to the Limited Edition by merely swapping the case lid from an older, existing 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.[12]

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 Apple 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, disparate computers.

The IIGS was 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 was 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 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 products. Apple Records considered the inclusion of the Ensoniq chip in the IIGS as a violation of that agreement.

Software features

Broadly speaking, software that runs on the Apple IIGS can be divided into two major categories: 8-bit software compatible with earlier Apple II systems such as the IIe and IIc, and 16-bit IIGS software, most of which runs under the Apple IIGS System Software and takes advantage of its advanced features, including a near clone of the Macintosh graphical user interface.

8-bit 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.[6] The IIGS could run all of Apple's earlier Apple II operating systems: Apple DOS, ProDOS 8, and Apple Pascal. It was also compatible with nearly all 8-bit software running under those systems. Like the Apple II+, IIe, and IIc, the IIGS also included Applesoft BASIC and a monitor (which could be used for very simple assembly language programming) in ROM, so they could be used even with no operating system loaded from disk. The 8-bit software ran twice as fast unless the user turned down the processor speed in the IIGS control panel.

Apple IIGS System Software

The Apple IIGS System Software utilized 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 were based on the ProDOS 16 operating system, which was based on the original ProDOS operating system for 8-bit Apple II computers. Although it was modified so that 16-bit Apple IIGS software could run on it, ProDOS 16 was written largely in 8-bit code and did 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 utilized the unique capabilities of the IIGS and included many valuable new features. The Apple IIGS System Software was substantially enhanced and expanded over the years during which it was developed, culminating in its final 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 some bugs. So the Apple IIGS got an update of its System Software after more than 21 years.[13]

Graphical user interface

Similar to the Macintosh, the IIGS system software provided 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 resided in the computer's ROM and some of which was loaded from disk. Only one major application could run at a time, although other, smaller programs, known as Desk Accessories, could be used simultaneously. The IIGS had a Finder application very similar to the Macintosh's, which allowed the user to manipulate files and launch applications. By default, the Finder was displayed when the computer started up and whenever the user quit an application that had been started from it, although the startup application could be changed by the user.

Software companies complained that Apple did not provide technical information and development tools to create IIGS software. In 1988 Compute! reported that both Cinemaware and Intergalactic Development had to write their own tools to use IIGS audio, with the latter stating that "these sorts of problems … are becoming well known throughout the industry".[14]


The IIGS System Software could be extended through various mechanisms. New Desk Accessories were small programs ranging from a calculator to simple word processors that could be used while running any standard desktop application. Classic Desk Accessories also served as small programs available while running other applications, but they used the text screen and could be accessed even from non-desktop applications. Control Panels and initialization files were other mechanisms that allowed various functions to be added to the system. Finder Extras permitted new capabilities to be added to the Finder, drivers could be used to support new hardware devices, and users could also add "tools" that provided various functions that other programs could utilize easily. These features could be used to provide features never planned for by the system's designers, such as a TCP/IP stack known as "Marinetti".

Multitasking capability

An interesting feature of the IIGS was that multitasking was possible. A UNIX-like multitasking kernel was produced, called GNO/ME, which ran under the GUI and provided preemptive multitasking. In addition, a system called The Manager could 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 from an Apple IIe

Back view of IIGS upgrade; note 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 Apple IIe motherboard with a 16-bit Apple 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 Apple 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 to mid-1989) had electrical connections for the IIe power supply and keyboard present, although only about half of those produced had the physical plug connectors factory pre-soldered in, which were mostly reserved for the upgrade kits.

The replacement ID badges for the front lid, used in the Apple IIe-to-IIGS upgrade.

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 was 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 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 could 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 II GS designers' achievements are remarkable, but the burden of the classic 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 Apple II compatibility, [the IIGS] approaches but does not match or exceed current computer capabilities" of the Macintosh, Amiga, or 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.[5] inCider, which in September had warned that the next Apple II "needs (at least) ... a megabyte of RAM ... That's what the market wants",[15] 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 for the IIGS at this time is LearningWays' Explore-a-Story, which was released simultaneously for the good old 128K Apple //e and //c". The magazine concluded, "The moral is simple: Good hardware, even innovative hardware, won't give birth to good, new software overnight".[16]

Nibble was more positive, calling the price "fantastic" for "Steve Wozniak's dream machine". It praised the IIGS's "incredible" 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 // user community, you have earned our gratitude and admiration".[17] Compute! describing 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 Commodore Amiga and the Atari ST series". It described the IIGS's graphics "as different as night and day" from the Apple II 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".[18] 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". The magazine stated that many customers either chose the slightly more expensive Macintosh Plus or kept their inexpensive Apple IIc or IIe which ran AppleWorks well, with the IIGS "in a strange position" in between.[19]

BYTE‍ '​s 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 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 Amiga and ST. The other computers, he wrote, had both larger software libraries that used 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".[20] 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 ST's more powerful 68000 CPU with the IIGS's greater expandability and large Apple II software library.[6]

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.[21] In 1989 the magazine stated "One of the biggest complaints of IIGS-specific software is the way it imitates the pace of a zombie". You'd think 16-bit software had died and voodoo-transformed into a shuffling, stumbling imitation of real computer applications".[22] 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".[23] inCider also criticized the price increase, warning that it "opens the door further to low-cost MS-DOS computers".[24]

Technical specifications


  • WDC 65C816 running at 2.8 MHz
  • 8-bit data bus, with selectable 8 or 16 bit registers
  • 24 bit addressing, using a 16-bit address bus & a multiplexed bank address


  • 1.125 MB RAM built-in (256 KB in original) (expandable to 8.125 MB)
  • 256 KB ROM built-in (128 KB in original)

Video modes

Emulation video

  • 40 and 80 columns text, with 24 lines[25] (16 selectable foreground, background, border colors)
  • Low-Resolution: 40×48 (16 colors)
  • High-Resolution: 280×192 (6 colors)[26]
  • Double-Low-Resolution: 80×48 (16 colors)
  • Double-High-Resolution: 560×192 (16 colors)[26]

Native video

  • 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)[27]
    • 320×200 (3200 colors, selectable from 4,096 color palette)[27]
  • 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)[28]
    • 640×200 (64 colors, selectable from 4,096 color palette)[27]
    • 640×200 (800 colors, selectable from 4,096 color palette)[27]
  • Fill-mode
    • 320×200, sections of screens filled in on-the-fly for up to 60 frame/s full-screen animation
  • Mixed-mode
    • 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)[29]
    • Support for eight independent stereo speaker channels[30]


  • Seven Apple II Bus slots (50-pin card-edge)
  • IIGS Memory Expansion slot (44-pin card-edge)

Internal connectors

  • 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 microcontroller

External connectors

  • NTSC composite video output (RCA connector)
  • Joystick (DE-9)
  • Audio-out (18-inch mono phono jack)[30]
  • Printer-serial 1 (mini-DIN8)
  • Modem-serial 2 (mini-DIN8)
  • Floppy drive (D-19)
  • Analog RGB video (DA-15)
  • Apple Desktop Bus (mini-DIN4)

Revision history

While in production between September 1986 and December 1992, the Apple IIGS remained relatively unchanged from its original 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 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 revision shipped with the machine and was notably bug-ridden. Some limitations included the fact that the built-in RAM Disk couldn't be set larger than 4 MB (even if more RAM was present) and the firmware contained the very early System 1.x toolsets. It became incompatible with most native Apple IIGS software written from late-1987 onwards, and OS support only lasted up to System 3. The startup splash screen of the original ROM only displayed the words "Apple IIgs" at the top center of the screen, in the same fashion that previous Apple II models identified 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 allowed 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 splash screen.

Increase standard RAM to 512 KB

In March 1988, Apple began shipping Apple IIGS units with 512 KB of RAM as standard. This was done by pre-installing 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"), The Apple IIGS with 1 MB of RAM

In August 1989, Apple increased the standard amount of RAM shipped in the Apple 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, was 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 populated Apple IIGS Memory Expansion Card.

The new ROM firmware was now 256 KB in size 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 was a cleaner design that drew less power and resolved audio noise issues that interfered with the Ensoniq synthesizer in the original motherboard. Over four times more RAM was built-in, with double the ROM size, and an enhanced ADB micro-controller provided 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 was 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-Apple IIGS upgrade was removed, and some cost-cutting measures had some chips soldered in place rather than 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 Apple IIGS as the "ROM 3".

International versions

Like the Apple IIe and Apple IIc built-in keyboards before it, the detached Apple IIGS keyboard differed 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 was NTSC-only on all IIGS systems; users in PAL countries were expected to use an RGB monitor. This selectable internationalization made it quick and simple to "localize" any given machine. Also present in the settings was 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 difference (and also very modular, in the sense of converting a non-localized machine to a local one).


Apple designed the Apple IIe Card to transition Apple IIe customers to the 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.[31] 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 Power Macintosh only.[32][33][34] Apple did not officially support the project.[35] 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 institutions that signed a non-disclosure agreement.[36][37][38] It was never offered for public sale, but is now readily available on the internet, along with many third party Apple II emulators. Gus represents one of the few software emulators developed within Apple (officially or not), including MacWorks and Mac OS X Classic environment.

Apple IIGS developers

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 Apple II-originated game Castle Wolfenstein, came full circle back to the Apple II series when it was released for the Apple IIGS in 1994.

Two mainstream video games, Zany Golf and The Immortal, 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 Apple II, but later developed for the Apple IIGS.

Between the late 1980s and early 1990s, the Apple IIGS developed its own demoscene very similar in vein to that of the Amiga and Atari ST, albeit much smaller and lesser known. The most popular demo group was called FTA (Free Tools Association) and was from France. Two of their demos (Nucleus and Modulae) were very popular and were used by Apple itself and by retailers to show off the computer.

Prototype of the MEGA II chip was a large board containing mostly discrete logic parts called "El Grande".

Canceled developments

Compute! in 1989 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,[39][40] but no new computer appeared.[41]

VTech, makers of the Apple II-compatible Laser, announced plans for a IIGS compatible in 1988 for under $600.[42] It demonstrated a prototype in 1989, but the computer was never released due to licensing issues with Apple.

A project called "Avatar" in the early 1990s promised a 32-bit state-of-the-art machine that was backwards-compatible with the Apple IIGS. It was never finished or released.

Cirtech started work on, but never completed, a black-and-white Macintosh hardware emulation plug-in card for the Apple IIGS dubbed "Duet".

Timeline of Apple II family models

See also


  1. ^ Electronic and computer music By Peter Manning. 
  2. ^
  3. ^ Histoire de l'Apple IIGS, "Histoire de l'Apple IIGS"
  4. ^ Kavadias, Tony (July 24, 2004). "Apple II User Interfaces". Retrieved November 13, 2011. 
  5. ^ a b c Williams, Gregg; Grehan, Richard (October 1986). "The Apple II GS". BYTE. p. 84. Retrieved 4 November 2013. 
  6. ^ a b c Chien, Philip (April 1987). "The Apple IIGS". BYTE. p. 223. Retrieved 5 November 2013. 
  7. ^ Statt, Paul (1986-08). "Future II's". inCider. p. 14. Retrieved 10 August 2014. 
  8. ^ de Peyster, Deborah; Statt, Paul (1986-09). "Extras for the //x". inCider. p. 14. Retrieved 2 July 2014. 
  9. ^ "The Apple II Guide and Mark Twain". 
  10. ^ "Apple IIGS". 
  11. ^ " Museum". 
  12. ^ The original Apple II FAQ, the Apple IIGS
  13. ^ [2]
  14. ^ Keizer, Gregg (December 1988). "Where's Apple?". Compute!. p. 64. Retrieved 10 November 2013. 
  15. ^ Statt, Paul (1986-09). "Stattus Report". inCider. p. 110. Retrieved 2 July 2014. 
  16. ^ Statt, Paul (1986-11). "Visions of GS Software". inCider. p. 46. Retrieved 1 July 2014. 
  17. ^ Szetela, David (1986-10). "The New II". Nibble. p. 5. Retrieved 18 August 2014. 
  18. ^ Thornburg, David D. (1986-11). "The New Apple IIGS". Compute!. p. 18. Retrieved 4 July 2014. 
  19. ^ "II On II". Compute!'s Apple Applications. 1987-12. p. 8. Retrieved 18 August 2014. 
  20. ^ Webster, Bruce (1987-01). "View and Reviews". BYTE. p. 367. Retrieved 30 June 2014. 
  21. ^ Keizer, Gregg (November 1988). "IIGS Gets Going". Compute!. p. 66. Retrieved 10 November 2013. 
  22. ^ Keizer, Gregg (March 1989). "Apple II". Compute!. p. 58. Retrieved 10 November 2013. 
  23. ^ Keizer, Gregg (February 1989). "Stratospheric". Compute!. p. 50. Retrieved 10 November 2013. 
  24. ^ Muse, Dan (1988-11). "Born Old (But Not Ugly)". inCider. p. 8. Retrieved 1 July 2014. 
  25. ^ Effectively 140×192 in color, due to pixel placement restrictions.
  26. ^ 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.
  27. ^ 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).
  28. ^ 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.
  29. ^ Only 15 voices are available in most software due to firmware pairing oscillators and reserving one for timing.
  30. ^ a b While output from audio jack is mono, and all third party "stereo cards" only produced two channel stereo, the capability for supporting 8 channel stereo was present on the motherboard/chip.
  31. ^ ", The Apple }, THE BEGINNING OF THE END". September 25, 1991. Retrieved November 13, 2011. 
  32. ^ ", Apple II – Rumors, Facts and Fables – Part 2". September 15, 1996. Retrieved November 13, 2011. 
  33. ^ ", Me and the Apple II". Retrieved November 13, 2011. 
  34. ^ """, Museum, Screenshots: "Gus Emulator. Retrieved November 13, 2011. 
  35. ^ ", Run Apple IIgs programs on your Mac". April 2, 1997. Retrieved November 13, 2011. 
  36. ^ ", Washington Apple Pi's Apple II Page". Retrieved November 13, 2011. 
  37. ^ ", Apple II, Gus 1.0b4". September 29, 2007. Retrieved November 13, 2011. 
  38. ^ ", GenieLamp Apple II Vol.5, Issue 53, MESSAGE SPOTLIGHT: A few words about Gus". Retrieved November 13, 2011. 
  39. ^ Keizer, Gregg (February 1989). "Talk, Talk, Talk". Compute!. p. 51. Retrieved 10 November 2013. 
  40. ^ Keizer, Gregg (July 1989). "Apple II Forever?". Compute!. p. 55. Retrieved 11 November 2013. 
  41. ^ Keizer, Gregg (August 1989). "No IIGS Plus". 1989-08. p. 54. Retrieved 11 November 2013. 
  42. ^ Ferrell, Keith (April 1988). "Computers Win Big!". Compute!. p. 6. Retrieved 10 November 2013. 

External links

  • "The New Apple IIGS" from Compute! magazine (November 1986)
  • Apple II History from Steven Weyhrich
  • What is the Apple IIGS, reviews of many Apple IIGS applications