The Apple IIGS (also written as II GS) is a 16-bit personal computer made by Apple Computer, starting in September 1986. It is the fifth and most powerful model in the Apple II series. The "GS" in the name means "Graphics and Sound," which refers to its improved multimedia features, especially its advanced sound system. The computer works with earlier Apple II models, and Apple sold a kit to change an Apple IIe into a IIGS. Software designed for older 8-bit Apple II computers runs about three times faster on the IIGS by default.

This computer is very different from earlier models. It uses a WDC 65C816 microprocessor, has 256 KB to 1 MB of random-access memory (which can be expanded to 8 MB), and has a screen quality and color similar to the Amiga and Atari ST computers. It also includes a 32-channel Ensoniq wavetable synthesis chip for sound. The system came with a mouse and was the first Apple computer with a color graphical user interface. Apple introduced a color interface on the Macintosh II six months later. It also used the Apple Desktop Bus, a special connection for keyboards, mice, and other input devices.

The IIGS made it harder to tell the difference between Apple II and Macintosh computers. After the IIGS was released, Apple focused more on the Macintosh line and did not make any new IIGS models. The standard memory was increased to 512 KB in 1988 and to 1 MB in 1989. There were also two firmware updates. Apple stopped making the IIGS on December 4, 1992.

Hardware

The Apple IIGS improved upon the Apple IIe and Apple IIc. It used a custom chip called the Mega II to recreate the features of earlier models and included a new 16-bit microprocessor called the WDC 65C816. This processor operated at 2.8 MHz, which is faster than the 8-bit processors in older Apple II models. The 65C816 had 24-bit memory addressing, allowing the IIGS to use more RAM than previous models. The original processor in the IIGS was certified to run at up to 4 MHz. However, Apple continued to use the 2.8 MHz speed for the entire production of the IIGS, even though faster versions of the processor were available.

The IIGS had better graphics than earlier Apple II models. It supported higher resolution and more colors. For example, it could display 640×200 pixels with 2-bit color (4 colors) or 320×200 pixels with 4-bit color (16 colors). These modes could use up to 4,096 colors from a palette. By changing the palette on each scan line, the IIGS could show 3,200 colors at once.

The audio was created using an Ensoniq 5503 digital synthesizer chip with 32 sound channels. These channels could be paired to produce 15 stereo voices. The chip had 64 KB of dedicated memory for its operations.

The IIGS supported both 5.25-inch and 3.5-inch floppy disks. It had seven expansion slots compatible with Apple II models and a memory expansion slot for up to 8 MB of RAM. It also had ports for external floppy drives, two serial ports for printers and modems (which could connect to a LocalTalk network), an Apple Desktop Bus port for the keyboard and mouse, and composite and RGB video ports.

A built-in battery powered the real-time clock. Initially, the battery was non-replaceable, but later models had a removable lithium battery.

The IIGS could boot from an AppleShare server using AppleTalk over LocalTalk cabling. This feature was available more than a decade before similar capabilities were introduced in Mac OS 8.

The IIGS supported all text and bitmapped graphics modes from earlier Apple II models. Its Video Graphics Chip (VGC) added a "Super-High Resolution" mode with a wide color palette and no color bleeding or fringing. This mode supported 200 lines with either 320 or 640 pixels horizontally. Both modes used a 12-bit palette for 4,096 colors. Up to 3,200 colors could appear onscreen at once, with no more than 16 per line. A fill mode setting allowed fast graphics by repeating pixel colors along scan lines.

Each display row could independently choose between 320 or 640 pixels, fill mode (for 320 pixels), and any of 16 palettes. These settings created multiple display options:

• 320×200 pixels with one palette of 16 colors.
• 320×200 pixels with up to 16 palettes of 16 colors, allowing 256 colors onscreen.
• 320×200 pixels with up to 200 palettes of 16 colors, allowing 3,200 colors onscreen.
• 320×200 pixels with 15 colors per palette plus a fill-mode color.
• 640×200 pixels with 4 pure colors.
• 640×200 pixels with up to 16 palettes of 4 pure colors, allowing 64 colors onscreen.
• 640×200 pixels with up to 200 palettes of 4 pure colors, allowing 800 colors onscreen.
• 640×200 pixels with 16 dithered colors using two palettes of four pure colors each.

The IIGS's sound used an Ensoniq 5503 DOC chip designed by Bob Yannes, the creator of the SID chip in the Commodore 64. This chip was also used in professional synthesizers like the Ensoniq Mirage and ESQ-1. It had 32 oscillators, allowing up to 32 voices. Apple's firmware paired them for 16 voices, while tools like Apple MIDISynth grouped four oscillators per voice for richer sound. The IIGS was often called a 15-voice system because one voice was reserved for timing. Software not using Apple's tools could access all 32 voices.

The IIGS had a headphone jack on its back for monaural sound. Stereo sound required a third-party adapter. The Ensoniq chip could drive 16 speaker channels, but Apple's expansion connector only supported 8. The IIGS had 64 KB of dedicated memory for the Ensoniq chip's wavetable instruments.

Apple sold Bose Roommate amplified speakers for the IIGS, matching its platinum color and featuring a custom logo.

The IIGS's expansion slots allowed upgrades with hardware like SCSI adapters for hard drives and CD-ROM drives or adapters for modern 2.5-inch IDE drives. Apple II peripheral cards included accelerator cards to replace the original processor with faster ones.

Development

In January 1985, Steve Wozniak stated that Apple was studying the 65816 microprocessor. He claimed that an 8 MHz version of this chip could perform better than the 68000 microprocessor in most tasks, but any product using it would need to work with the Apple II computer. People began to talk about a new computer called the "Apple IIx." Reports said the IIx would use a 16-bit CPU, have one megabyte of RAM, and include improved graphics and sound. "IIx" was the name given to Apple's first project to create a new version of the Apple II based on the 65816 chip. However, the project faced delays when engineers tried to add coprocessors that would allow the computer to copy the functions of other systems. Early versions of the 65816 chip also had issues. These problems caused Apple to stop the IIx project.

Later, a new project was started, which led to the creation of the Apple IIGS. During development, this project had several names, including "Phoenix," "Rambo," "Gumby," and "Cortland."

Some design ideas from the failed Apple III computer were used in the Apple IIGS. For example, the GS/OS operating system included parts from the SOS system, which was also used in ProDOS. The IIGS also had a keyboard with special keys for controlling text speed and displayed colored text using ASCII characters.

Release

In honor of the 10th anniversary of the Apple II series and Apple Computer itself, a special limited edition of the Apple IIGS was released during its product launch. The first 50,000 units produced featured a printed copy of Steve Wozniak's signature ("Woz") in the front right corner of the case. Below the signature, a dotted line and the words "Limited Edition" were printed. Owners who sent in their Apple registration cards received a certificate of authenticity signed by Wozniak and 12 key Apple engineers, along with a letter from Wozniak himself. These items were printed using machines. The only difference between standard and Limited Edition models was the appearance, so some owners of newer models could switch to the Limited Edition by replacing the case lid from an older, likely nonfunctional machine.

When the Apple IIGS was released in September 1986, Apple announced a kit to upgrade Apple IIe computers to the IIGS. This followed Apple’s long tradition of offering upgrades for the Apple II’s main circuit board, which began in the earliest days of the Apple II and continued until Steve Jobs returned to Apple in 1997. The upgrade replaced the IIe’s motherboard with a 16-bit IIGS motherboard. Users brought their IIe computers to an authorized Apple dealership, where the IIe’s motherboard and lower baseboard were replaced with an IIGS motherboard and a new baseboard. The new baseboard had cutouts for the IIGS’s built-in ports. The upper half of the IIe case, keyboard, speaker, and power supply remained unchanged. New metal ID badges replaced those on the IIe’s front. Original IIGS motherboards made between 1986 and mid-1989 included electrical connections for the IIe’s power supply and keyboard, though only about half had the physical plug connectors already soldered in place. These were mostly used in the upgrade kits.

The upgrade cost $500, plus the user’s existing IIe motherboard. It did not include a mouse, and the keyboard, while functional, lacked a numeric keypad and did not support all features of the Apple Desktop Bus keyboard. Some expansion cards designed for the IIGS did not fit in the IIe’s slanted case. Many users found that the upgrade did not save much money after purchasing a 3.5-inch floppy drive, analog RGB monitor, and mouse.

Software features

Software that runs on the Apple IIGS is split into two main groups: 8-bit software that works with earlier Apple II systems like the IIe and IIc, and 16-bit IIGS software, which uses the computer’s advanced features, including a graphical user interface similar to the Macintosh.

Apple said the IIGS was over 99% compatible with Apple II software from that time. For example, one reviewer used demo programs stored on cassette from a 1977 Apple II on the IIGS. The IIGS can run all of Apple’s earlier Apple II operating systems, including Apple DOS, ProDOS 8, and Apple Pascal. It also works with nearly all 8-bit software designed for those systems. Like the Apple II+, IIe, and IIc, the IIGS includes Applesoft BASIC and a machine-language monitor (used for simple assembly language programming) stored in its ROM. These tools can be used even without loading an operating system from a disk. The 8-bit software runs nearly three times faster unless the user lowers the processor speed in the IIGS control panel.

Early versions of the IIGS system software were based on ProDOS 16, which was built from the original ProDOS system used on 8-bit Apple II computers. ProDOS 16 was mostly written in 8-bit code and did not fully use the IIGS’s advanced features. Starting with System Software version 4.0, ProDOS 16 was replaced by a 16-bit operating system called GS/OS.

The IIGS system software was improved over time, ending with its final official version, System 6.0.1, released in 1993. In July 2015, members of a French computer group released an unofficial version called "System 6.0.2" (later followed by 6.0.3 and 6.0.4), which mainly fixed bugs.

The IIGS includes a mouse-driven graphical user interface similar to the Macintosh. This interface is created by a "toolbox" of code, part of which is stored in the computer’s ROM and part of which is loaded from a disk. Only one major application can run at a time. Smaller programs, called Desk Accessories, can be used alongside it. This distinction originated on the Mac. The IIGS has a Finder file manager application, very similar to the Mac’s, for managing files and launching programs. The Finder appears when the computer starts up and after the user closes an application. The startup application can be changed by the user.

GNO/ME, a third-party UNIX-like kernel, was sold from 1991 to mid-1996. It ran under the GUI and provided preemptive multitasking. The Manager, developed by Brainstorm Software and published by Seven Hills, was a MultiFinder-like add-on sold from 1993 to 1995. It made the Finder more like the one on the Macintosh, allowing major software (not just accessory programs) to run simultaneously through cooperative multitasking.

Reception

In October 1986, BYTE noted that the Apple IIGS designers did a remarkable job. However, the old Apple II design might have limited their progress, preventing them from making major improvements beyond making the computer smaller. The magazine also said that the need to support older Apple II systems made the IIGS less powerful than newer computers like the Macintosh, Amiga, or Atari ST. It predicted that many companies would focus on improving older Apple II products instead of creating new software that uses the IIGS’s full capabilities.

In September, inCider warned that the next Apple II needed at least one megabyte of RAM, which was what customers wanted. In November, the magazine reported that many software developers avoided creating new programs for the IIGS because they feared the programs would only work on that computer. Instead, they updated older Apple II programs. The most notable IIGS-specific program at the time was Explore-a-Story by LearningWays, which was also released for older Apple II models. The magazine concluded that even the best hardware cannot quickly produce new, high-quality software. By 1988, the IIGS was ranked as the fourth-fastest Apple II computer, behind the Apple IIc Plus, Laser 128EX/2, and IIe with Zip Chip.

Nibble praised the IIGS, calling it "Steve Wozniak’s dream machine" with a "fantastic" price. It highlighted the computer’s ability to work with older Apple II software, its advanced graphics, and its sound quality. However, it noted that the IIGS was slower than the Macintosh. Nibble expected Apple to release new products to better separate the IIGS and Macintosh lines. The magazine concluded that the IIGS was a highly advanced computer, calling it "the finest assemblage of chips and resistors ever soldered together" and expressing gratitude to Apple for its work.

In November 1986, Compute! described the IIGS as "two machines in one," bridging the gap between the Macintosh and Apple IIe. It said the IIGS’s graphics were very different from earlier Apple II models and its sound was unmatched, appealing to music fans. The magazine reported that over 100 outside developers were creating software for the IIGS and predicted that more programs would be made to take advantage of its features, encouraging users to move away from older Apple II models.

However, in December 1987, Compute!’s Apple Applications reported that many publishers canceled or delayed IIGS software plans, instead focusing on older Apple II models like the IIc and IIe. Many IIGS programs were just updated versions of older Apple II software with added color and mouse support. The magazine noted that the most popular product for the IIGS was AppleWorks, which lacked color, a mouse, and graphics. Many customers chose the more expensive Macintosh Plus or stayed with older, cheaper Apple II models that ran AppleWorks well, leaving the IIGS in an unclear position.

In January 1987, BYTE’s Bruce Webster compared a $2,500 IIGS package to a $1,500 Atari ST setup. He gave the IIGS "qualified approval," saying it was needed to keep the Apple II line alive for a short time but not enough to make it competitive. A BYTE review in April 1987 said the IIGS had potential but needed a faster processor and more memory. It advised buyers to compare the IIGS’s expandability and large Apple II software library with the more powerful 68000 CPUs in the Macintosh, Amiga, and Atari ST.

In 1988, Compute! urged Apple to improve the IIGS’s speed, stating that it was too slow for most software. In 1989, the magazine criticized IIGS-specific programs for being slow, comparing their performance to "a zombie." It noted that a basic IIGS setup with a color monitor, two disk drives, and an ImageWriter II cost over $3,000, a price it called "staggering." inCider also criticized the price increase, saying it encouraged customers to choose cheaper MS-DOS computers.

Some software companies said Apple did not provide enough technical support or tools to create IIGS-specific programs. In 1988, Compute! reported that companies like Cinemaware and Intergalactic Development had to develop their own tools to use the IIGS’s audio features. Intergalactic Development stated that these challenges were becoming common in the industry.

Technical specifications

• Uses a WDC 65C816 processor that operates at 2.8 MHz
• An 8-bit data bus that can be set to use either 8-bit or 16-bit registers
• Supports 24-bit memory addressing

• RAM options include 256 KB, 512 KB, or 1 MB, depending on the release year. Up to 8 MB of RAM can be added.
• ROM options include 128 KB or 256 KB

• Displays text in 40 or 80 columns with 24 lines
• Low resolution: 40×48 pixels with 16 colors
• High resolution: 280×192 pixels with 6 colors
• Double low resolution: 80×48 pixels with 16 colors
• Double high resolution: 560×192 pixels with 16 colors

• Displays text in 40 or 80 columns with 24 lines (16 selectable foreground, background, and border colors)
• Super-high resolution (320 mode): 320×200 pixels with 16 colors, 256 colors, or 3,200 colors (all from a 4,096-color palette)
• Super-high resolution (640 mode): 640×200 pixels with 4 colors, 16 dithered colors, 64 colors, or 800 colors (all from a 4,096-color palette)
• Fill mode (320×200): Pixels to the right of a non-zero color are displayed in that color until another non-zero pixel is reached
• Mixed mode (320/640×200): Horizontal resolution can be set per line

• Features an Ensoniq 5503 digital oscillator chip with 8-bit audio resolution and 64 KB of dedicated sound RAM
• Supports 32 oscillator channels (16 voices when paired)
• Includes eight independent stereo speaker channels

• Seven Apple II Bus slots using 50-pin card-edge connectors
• One IIGS Memory Expansion slot using 44-pin card-edge connectors

• Game I/O socket using 16-pin DIP connectors
• Ensoniq I/O expansion connector using 7-pin Molex connectors

• IWM (Integrated Woz Machine) for floppy drives
• VGC (video graphics controller) for video
• Mega II (Apple IIe computer on chip)
• Ensoniq 5503 DOC (sample-based synthesis)
• Zilog Z8530 SCC (serial port controller)
• Apple Desktop Bus microcontroller
• FPI (Fast Processor Interface) or CYA (Control Your Apple)

• NTSC composite video output (RCA connector)
• Joystick (DE-9)
• 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 (mini-DIN4)

Revision history

From September 1986 to December 1992, the Apple IIGS had few major changes from its first design. However, Apple made some updates to the system, including two new firmware versions stored in ROM chips and a redesigned motherboard.

In the first year of production, the Apple IIGS came with an early version of its firmware that had many errors. This version limited the built-in RAM Disk to 4 MB, even if more memory was installed, and used outdated System 1.x tools. It became incompatible with most Apple IIGS software created after late 1987, and support for the operating system ended at System 3. The original ROM’s startup screen only showed the words “Apple IIgs” centered at the top of the screen, similar to earlier Apple II models.

Early versions of the Apple IIGS had a defective video graphics controller chip that caused visual issues in emulated Apple IIe and IIc display modes. These problems included flickering or pink static between characters and pixels in 80-column text and monochrome graphics. Many users noticed this while using AppleWorks classic or the Mousedesk application. Apple fixed the issue by offering a free chip replacement to affected owners.

In August 1987, Apple released an updated ROM included in all new machines and provided as a free upgrade for existing owners. This version added the System 2.x tools and fixed many errors. The update was critical because software developers, including Apple, stopped supporting the original ROM after its release. Most Apple IIGS software created after late 1987 required ROM version 01 or newer to function, including the GS/OS operating system. This update also allowed the RAM Disk to use up to 8 MB of memory, added features for programmers, and displayed the ROM version and copyright information on the startup screen.

In March 1988, Apple began shipping IIGS units with 512 KB of RAM as standard. This was achieved by pre-installing the Apple IIGS Memory Expansion Card (previously sold separately) into the memory slot. The card had 256 KB of RAM and empty sockets for future expansion. The motherboard’s built-in memory remained at 256 KB, and existing owners were not offered this upgrade.

In August 1989, Apple increased the standard RAM in the IIGS to 1.125 MB by adding more memory directly to the motherboard. This required a redesign of the motherboard and included minor improvements. However, the new motherboard and ROM firmware were not offered as upgrades to existing owners. Apple stated that most features of the updated machine could be achieved by installing System 5 and fully populating an Apple IIGS Memory Expansion Card on older models.

The new ROM firmware expanded to 256 KB and included the System 5.x tools, which improved the machine’s performance by up to 10%. This was due to faster access to tools stored in ROM compared to loading them from disk and more optimized routines. Additional features included improved programmer tools, a cleaner control panel with better mouse support and RAM Disk functions, more flexible Appletalk support, and improved slot-mapping.

The new motherboard used less power, reduced audio noise that interfered with the Ensoniq synthesizer, and had twice as much built-in RAM and double the ROM size. A newer Apple Desktop Bus microcontroller added support for sticky keys, mouse emulation, and keyboard LED features on extended keyboards. Hardware shadowing of Text Page 2 improved compatibility with classic Apple II video modes. The clock battery was now user-replaceable, and a jumper was added to disable the text-based control panel for school use. Support for upgrading Apple IIe models to the IIGS was removed, and some components were soldered in place to reduce costs. Since the new firmware only worked with the updated motherboard and no further updates were released, users often called this version the “ROM 3.”

International versions

The Apple IIGS keyboard, unlike earlier models such as the Apple IIe and Apple IIc, had different keycaps depending on the region where it was sold. Some keyboards included special characters for local languages, such as French accents like "à," "é," and "ç" on the Canadian version, or the British Pound symbol "£" on the UK version. However, unlike previous Apple II models, the keyboard's layout and key shapes were the same worldwide. The computer's internal ROMs also worked the same for all countries, supporting all keyboard layouts. To use local characters or switch between 50 Hz and 60 Hz video refresh rates, users changed settings in the computer's built-in software control panel. The composite video output on all IIGS systems used NTSC format, so users in PAL regions needed an RGB monitor or a TV with RGB SCART input. This design made it easy to adjust the computer for different regions. The control panel also allowed users to switch between QWERTY and DVORAK keyboard layouts, similar to the Apple IIc. Outside North America, the Apple IIGS came with a 220 V power supply, and the plastic keycaps were the only physical differences between models. These features made the system highly adaptable for different regions.

Legacy

The Apple Desktop Bus was the main way most input devices connected to Macintosh computers for a long time. It first appeared on the Apple IIGS. Also, the standardized ports and addition of SCSI created a standard that let Apple unify their peripheral options for both Apple II and Macintosh computers, allowing one device to work with different types of computers.

The Apple IIGS was the first Apple product to use the new color, a warm gray called "Platinum." This color became Apple's standard for most products for the next ten years. The IIGS was the second major Apple computer design, after the Apple IIc, where Apple worked with Hartmut Esslinger’s team at Frog Design. The new company color and matching peripherals started the Snow White design language, which was used for five years.

The Apple IIGS included a professional sound chip, which was praised by developers and users. People hoped it would be added to Macintosh computers, but it led to another lawsuit from Apple Corps. Because of a past trademark agreement with Apple Corps, Apple Computer had promised not to release music-related products. Apple Corps saw the Ensoniq chip in the IIGS as breaking that agreement.

John Carmack, co-founder of id Software, began his career by creating software for the Apple IIGS. He worked with John Romero and Tom Hall. The game Wolfenstein 3D, based on the 1981 Apple II game Castle Wolfenstein, was released for the Apple IIGS in 1998.

Two popular video games, Zany Golf and The Immortal, were designed by Will Harvey. They started as Apple IIGS games and were later released on other platforms, including the Sega Genesis.

Pangea Software began as a developer of Apple IIGS games. Naughty Dog’s first published game was for the 8-bit Apple II, and the company later developed games for the IIGS.

Apple created the Apple IIe Card to help users move from Apple IIe computers to Macintosh LC computers, especially schools with large investments in Apple II software. Apple considered making an LC plug-in IIGS card but decided it would cost as much as an entire LC and canceled the idea. However, schools had significant investments in IIGS software, making switching to Macintosh less appealing. To help schools transition, Apple employees Dave Lyons and Andy Nicholas created a software emulator called Gus during their free time. Gus ran only on Power Macintosh computers. Apple did not officially support the project but shared it for free with schools and institutions that signed a non-disclosure agreement. Gus was never sold to the public but is now available online, along with other Apple II emulators. Gus is one of the few software emulators developed by Apple, including MacWorks and the Mac OS X Classic environment. Gus was demonstrated in Rhapsody’s Blue Box at WWDC 1997.

Rumors and canceled developments

The "Mark Twain" prototype (named after Mark Twain's quote "The reports of my death are greatly exaggerated") was expected to have the "ROM 04" version. However, discovered prototypes do not include any new ROM code. It also had an 8 MHz 65C816 processor, a built-in SuperDrive, 2 MB of RAM, and a hard drive.

In August 1988, inCider magazine reported that Apple was working on a new Apple IIGS. The report mentioned it would have a faster CPU, better graphics (double the vertical resolution, 256 colors per scanline, and 4,096 colors per screen), 768 KB of RAM, 256 KB of ROM, 128 KB of sound DOC-RAM, and a built-in SCSI port. No new machine was released that year.

In 1989, Compute! magazine wrote about rumors that Apple might announce a "IIGS Plus" at the May AppleFest. This version was expected to have a processor two to three times faster, 768 KB to 1 MB of RAM, and a SCSI port. These rumors were partly based on Apple CEO John Sculley saying the IIGS would get a new CPU in 1989. No new computer was released, but in August, the IIGS began shipping with 1 MB of RAM as the standard configuration.

VTech, the company that made the 8-bit Apple II-compatible Laser 128, announced plans for an IIGS-compatible computer in 1988 for under $600. They showed a prototype in 1989, but the computer was never released.

Cirtech created a working prototype of a black-and-white Macintosh hardware emulation plug-in card for the IIGS called "Duet." It used a 68020 processor, custom ROM, and up to 8 MB of RAM. Cirtech claimed it performed better than the Macintosh IIcx. The project was canceled because the cost of the board was expected to be too high.