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|image=AppleIIGSPC.png
|imagecaption=An Apple II<span style="font-size:75%">GS</span> PC.
|developer=[[Apple Inc.|Apple Computer, Inc.]]
|type=[[:Category:Computers|Computers]]
|release=September 1986
|discontinued=December 1992
|predecessor = [[Apple II Line|Apple II]]
|emulated={{✓}}
}}
The '''[[Apple II Line|Apple II]]<span style="font-size:75%">GS</span> ''' is a 16-bit PC produced by Apple Computer Inc. It was created to compete with the [[Amiga Line|Amiga]] and the [[Atari ST Line|Atari ST]] lines of PCs.
Despite the Apple II<span style="font-size:75%">GS</span> name, it is a completely different architecture. The system has a chip called the “Mega II” which is an [[Apple II Line|Apple //e]] on a chip, making it fully backwards compatible with Apple ][ software.
It was the first machine from Apple to use the Apple Desktop Bus and the first to provide a colour version of QuickDraw since the first colour Macintosh was not available until 1987. However it does not provide a high-resolution square pixel mode.
==Emulators==
{|class="wikitable" style="text-align:center"
!scope="col"|Name
!scope="col"|Operating systemPlatform(s)
!scope="col"|Latest version
! scope="col"|<abbr title="Free/Libre and Open-Source Software">FLOSS</abbr>
!scope="col"|Active
!scope="col"|[[Recommended Emulators|Recommended]]
|-
! colspan="7"|PC / x86
|-
|[[KEGS]]
|Multi-platformalign=left|{{Icon|Windows|Linux|macOS}}|0[https://sourceforge.91net/projects/kegs/files {{KEGSVer}}]|{{✓}}|{{✗✓}}
|{{✓}}
|-
|[[MAMEGSplus]]|Multi-platformalign=left|{{Icon|Windows|Linux|macOS}}|[https://github.com/digarok/gsplus/releases {{MAMEVerGSplusVer}}]
|{{✓}}
|{{✗}}
|{{~}}
|-
|[[GSplus]https://david-schmidt.github.io/gsport GSport]|Multi-platformalign=left|{{Icon|Windows|Linux|macOS}}|{{GSportVer}}|0.14{{✓}}
|{{✓}}
|?{{✗}}
|-
|[[GSportMAME]]|Multi-platformalign=left|{{Icon|Windows|Linux|macOS|FreeBSD}}|0[http://www.mamedev.org/release.31html {{MAMEVer}}]|{{✓}}|{{✓}}
|{{✗}}
|}
==Processor==
The central processor is a 65816, a backwards-compatible 16-bit update to the 6502 that was also used in the Super Nintendo. It runs natively at 2.8Mhz but will slow down to ~1Mhz when in classic Apple II emulation mode or when writing to video memory.
==Graphics Capabilities==
In addition to RGB emulations of the existing Apple II artefact composite video modes, the IIgs adds 320x200 and 640x200 RGB colour modes; the former in various combinations of 16 colours per line and the latter at 4 colours per line (including a hardware dithering mode that acts a little like 16 colours per line). Each line may use any of 16 palettes, making a total of 256 colours on screen without raster-linked palette changes.
There is also some support for 'fill mode', in which colour 0 means "repeat the last non-zero colour", designed to aid in fast single-colour fills.
Colours are selected from a 12-bit RGB 4,096 colour palette; the IIGS therefore has the same total colour range as its contemporaries the Commodore Amiga, the Atari STE and the Acorn Archimedes.
However it is subject to a number of deficiencies: there is a single buffer for video only — double buffering is not supported — and it supports neither hardware scrolling nor hardware sprites; and as all writes into video memory clock the CPU down to 1Mhz these are expensive to perform in software.
==Audio Capabilities==
The IIGS provides a 32-channel wavetable Ensoniq sound chip, which uses 64kb for samples.
The OS by default configures this as 15 stereo channels and uses the remaining two channels as interrupt counters; the IIGS is therefore often described as a 15-channel machine.
{{Apple}}
[[Category:Computers]]
