Editing Apple IIGS (section)

== Hardware ==
The Apple IIGS made significant improvements over the [[Apple IIe]] and [[Apple IIc]]. It emulates its predecessors via a custom [[integrated circuit|chip]] called the [[Mega II]] and uses the then-new [[WDC 65C816]] [[16-bit computing|16-bit]] [[microprocessor]]. The processor runs at {{nowrap|2.8 [[megahertz|MHz]]}}, which is faster than the [[8-bit computing|8-bit]] processors used in the earlier Apple II models. The 65C816 allows the IIGS to address considerably more [[random-access memory|RAM]]. The original 65C816 processor used in the IIGS was certified to run at up to {{nowrap|4&nbsp;MHz}}.<ref name=score>{{cite web|title=Histoire de l'Apple IIGS|url=http://www.apple-iigs.info/histoire.php|language=fr|access-date=June 1, 2011|archive-date=September 4, 2011|archive-url=https://web.archive.org/web/20110904053910/http://www.apple-iigs.info/histoire.php|url-status=live}}</ref> Faster versions of the 65C816 processor were readily available, with speeds of between 5 and 14&nbsp;MHz, but Apple kept the machine at 2.8&nbsp;MHz throughout its production run.<ref>{{cite web |url=https://lowendmac.com/2015/apple-iigs-more-power-more-colors-awesome-sound/ |title=Apple IIGS: More Power, More Colors, Awesome Sound |date=29 November 2015 |first=Daniel |last=Knight |website=LowEndMac |access-date=July 7, 2020 |archive-date=August 7, 2020 |archive-url=https://web.archive.org/web/20200807003327/https://lowendmac.com/2015/apple-iigs-more-power-more-colors-awesome-sound/ |url-status=live }}</ref>

Its graphical capabilities are superior to the rest of the Apple II series, with higher resolution video modes and more color. These include a 640×200-pixel mode with 2-bit [[color depth]] and a 320×200 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 per [[scan line]], it is possible to display 3,200 colors at once.<ref>{{cite web|url=https://www.whatisthe2gs.apple2.org.za/dream-grafix/|website=What Is the Apple IIGS?|title=Dream Grafix|quotation=[…] the use of 3200 colours on screen at once, a technique involving an individual 16 colour palette every row of pixels along the IIGS super hi-res screen mode.|access-date=2023-01-17}}</ref>

Audio is generated by a [[Ensoniq]] 5503 digital synthesizer chip with 32 channels of sound. These channels can be paired to produce 15 voices in stereo.{{r|byte198610}} There is 64 KB of dedicated RAM for use by the 5503.

[[File:AST RamStakPlus memory board (cropped).jpg|thumb|[[AST Research|AST]] RamStakPlus memory board for Apple IIGS]]
The IIGS supports both 5.25-inch and 3.5-inch [[floppy disk]]s and has seven general-purpose expansion slots compatible with those on the [[Apple II]], [[Apple II+|II+]], and IIe. It also has a memory expansion slot for up to 8&nbsp;[[megabyte|MB]] of RAM. The IIGS has ports for external floppy disk drives, two [[serial port]]s for devices such as [[printer (computing)|printers]] and [[modem]]s (which can also be used to connect to a [[LocalTalk]] network), an [[Apple Desktop Bus]] port to connect the [[computer keyboard|keyboard]] and [[computer mouse|mouse]], and [[composite video|composite]] and [[RGB color model|RGB]] video ports.<ref name="byte198610">{{cite magazine | title=The Apple IIGS |volume=11|number=10| url=https://archive.org/stream/byte-magazine-1986-10/1986_10_BYTE_11-10_Public_Domain_Powerhouses#page/n95/mode/2up | magazine=[[Byte (magazine)|BYTE]] |publisher=UBM Technology Group|issn=0360-5280|oclc=637876171|location=United States| date=October 1986 | access-date=4 November 2013 |author1=Williams, Gregg |author2=Grehan, Richard | pages=84}}</ref>

A [[real-time clock]] is maintained by a built-in battery (initially 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]] [[communication protocol|protocol]], over [[LocalTalk]] cabling.<ref>{{Cite web |title=Remote booting a IIgs |url=http://www.synack.net/~bbraun/iigsboot.html |access-date=2023-12-17 |website=www.synack.net}}</ref> This was over a decade before [[NetBoot]] offered the same capability to computers running [[Mac OS 8]] and beyond.<ref>{{Cite web|url=https://www.hackster.io/news/a-bad-apple-8aad8a66b519|title=A Bad Apple?|website=Hackster.io}}</ref>

=== Graphics ===
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In addition to supporting all the text and bitmapped [[Apple II graphics]] modes of earlier models, the Apple IIGS's Video Graphics Chip (VGC) introduced a new "Super-High Resolution" mode with a vastly wider color palette and no [[Composite artifact colors|color bleeding and fringing]]. Super-High-Resolution supports 200 lines, in either 320 or 640 pixels horizontally. Both modes use a [[List of monochrome and RGB color formats#12-bit RGB|12-bit palette]] for a total of 4,096 possible colors. There can be between 4 and 3,200 colors onscreen at once, with no more than 16 per line. A ''fill mode'' setting allowing fast solid-fill graphics by automatically repeating a pixel's color to the right along the same scan line&mdash;until a different color pixel is reached.

Each row of the display can independently select either 320 or 640 pixels, fill mode (320 pixels only), and any of the 16 palettes. These settings provide many possibilities:

* 320×200 pixels with a single palette of 16 colors.
* 320×200 pixels with up to 16 palettes of 16 colors. 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. 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. Color 0 in the palette is replaced by the last non-zero color pixel displayed on the scan line (to the left).
* 640×200 pixels with 4 pure colors.
* 640×200 pixels with up to 16 palettes of 4 pure colors. 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.
* 640x200 pixels with up to 200 palettes of 4 pure colors. 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 4 colors, allowing for up to 800 colors on the screen at once.
* 640×200 pixels with 16 dithered colors. 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.

=== Audio ===
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The Apple IIGS's sound is provided by an Ensoniq 5503 DOC (Digital Oscillator Chip) [[wavetable synthesis]] chip designed by [[Bob Yannes]], creator of the [[MOS Technology 6581|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 [[synthesizer]]s. The chip has 32 oscillators, which allows for a maximum of 32 voices (with limited capabilities when all used independently), though Apple's [[firmware]] pairs them for 16 voices, to produce fuller and more flexible sound, as do most of the standard tools of the operating system (the Apple MIDISynth toolset goes even a step further for richer sound, grouping four oscillators per voice, for a limit of seven-voice audio). The IIGS is often referred to as a 15-voice system, because one voice, or "sound generator" consisting of two oscillators, is always reserved as a dedicated clock for the sound chip's timing [[interrupt]] generator. Software that does not use the system firmware, or uses custom-programmed tools (certain games, demos, and music software), can access the chip directly and take advantage of all 32 voices.

A standard {{frac|1|8}}-inch headphone jack is on the back of the case, and standard stereo computer speakers can be attached there. This jack provides only [[monaural sound]] and a third-party adapter card is required for stereo;<ref name="chien198704">{{cite magazine | url=https://archive.org/stream/byte-magazine-1987-04/1987_04_BYTE_12-04_Instruction_Set_Strategies#page/n245/mode/2up | title=The Apple IIGS | magazine=[[Byte (magazine)|BYTE]] |publisher=UBM Technology Group|volume=10|number=4|issn=0360-5280|oclc=637876171| date=April 1987 | access-date=5 November 2013 | author=Chien, Philip | pages=223}}</ref> despite that, the Ensoniq and virtually all native software produces stereo audio. The Ensoniq can drive 16 speaker output channels, but the [[Molex connector|Molex]] expansion connector Apple provided only allows 8. There is 64 KB of dedicated memory (DOC-RAM) on the IIGS motherboard, separate from system memory, for the Ensoniq chip to store its sampled wavetable instruments.

To exploit the IIGS's audio capabilities, during its introduction, Apple sold [[Bose Corporation|Bose]] [[Apple speakers#Bose RoomMate speakers|Roommate]] amplified speakers for the computer (matching its platinum color and with custom Bose/Apple logo grille covers).

=== Expansion ===
[[File:Applescsi.JPG|thumb|An Apple SCSI expansion card installed in an Apple IIGS]]

The expansion slots on the IIGS can be used to increase the computer's capabilities with contemporary and modern hardware, such as [[SCSI]] host adapters for external SCSI devices like hard drives and [[CD-ROM drive]]s, or adapters for more recent internal 2.5-inch [[integrated drive electronics|IDE]] hard drives. Available [[Apple II peripheral cards]] include accelerator cards, which replace the computer's original processor with a faster one.