Apple IIGS emulators: Difference between revisions
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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. | 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== | ==Emulators== | ||
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{|class="wikitable" style="text-align:center" | {|class="wikitable" style="text-align:center" | ||
!scope="col"|Name | !scope="col"|Name | ||
!scope="col"| | !scope="col"|Platform(s) | ||
!scope="col"|Latest version | !scope="col"|Latest version | ||
!scope="col"|Active | !scope="col"|Active | ||
!scope="col"|[[Recommended Emulators|Recommended]] | !scope="col"|[[Recommended Emulators|Recommended]] | ||
|- | |||
! colspan="6"|PC / x86 | |||
|- | |- | ||
|[[KEGS]] | |[[KEGS]] | ||
| | |align=left|{{Icon|Windows|Linux|macOS}} | ||
| | |{{KEGSVer}} | ||
|{{✗}} | |{{✗}} | ||
|{{✓}} | |{{✓}} | ||
|- | |- | ||
|[[GSplus]] | |[[GSplus]] | ||
| | |align=left|{{Icon|Windows|Linux|macOS}} | ||
| | |{{GSplusVer}} | ||
|{{✓}} | |{{✓}} | ||
|{{~}} | |{{~}} | ||
|- | |- | ||
|[ | |[https://david-schmidt.github.io/gsport GSport] | ||
| | |align=left|{{Icon|Windows|Linux|macOS}} | ||
| | |{{GSportVer}} | ||
|{{ | |{{✓}} | ||
|{{✗}} | |{{✗}} | ||
|- | |- | ||
|[[MAME]] | |[[MAME]] | ||
| | |align=left|{{Icon|Windows|Linux|macOS|FreeBSD}} | ||
|{{MAMEVer}} | |{{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}} | {{Apple}} | ||