Editing Apple IIGS Hardware Reference

<pdf> File:Apple IIGS Hardware Reference 1989.pdf </pdf>

The '''Apple IIGS Hardware Reference''', second edition, "for Apple IIGS and 1 MB Apple IIGS" (Apple Computer, Inc., 1989; published by Addison-Wesley), is Apple's own hardware reference for the [[Apple IIGS]].

== What is in it ==
* '''Processor speed''' - selectable between 1.024 MHz and 2.8 MHz. FPI refresh cycles reduce the effective speed of programs running in RAM '''by about 8 per cent'''; programs in ROM run at the full 2.8 MHz.
* '''Memory''' - 128K of fast (FPI) RAM and 128K on the Mega II side, 256K in total, or 1 MB on the 1 MB logic board; 128K of ROM, 256K on the 1 MB board; '''up to 4 MB of expansion RAM and up to 1 MB of expansion ROM'''.
* '''Super Hi-Res''' - 320 or 640 pixels across by 200 lines, 16 colours per line chosen from 4096. A 320-mode pixel can be any of the 16 palette colours; a 640-mode pixel can be one of only four, with the palette split into four groups of four so that different pixels in a line can still take any of the 16.
* '''Sound''' - the Ensoniq 5503 Digital Oscillator Chip, 32 independent oscillators, 64K of dedicated sound RAM, interfaced through the Sound GLU. Output is through the built-in speaker, the external speaker jack, or the '''7-pin molex connector J-25'''. Splitting the oscillators into up to eight channels requires '''external demultiplexer hardware''' on that connector: the built-in output is one mixed channel.
* '''The 1 MB (ROM 3) logic board''' - 1 MB of RAM, 256K of ROM with the toolbox utilities in it, a new ADB microcontroller providing sticky keys and the keyboard mouse, text page 2 shadowing, a cold-boot bit in the Speed register, and the fact that it '''no longer supports the built-in Apple IIe style keyboard - only ADB keyboards'''.
* The built-in real-time clock with its backup battery, the slot and memory expansion connector pinouts, and the power connector.

Download: [[:File:Apple IIGS Hardware Reference 1989.pdf|Apple IIGS Hardware Reference 1989.pdf]]

== See also ==
* [[Apple IIGS]]
* [[Apple IIGS ROM Revision Summary]]

[[Category:Apple Documentation]]
[[Category:Documentation]]
[[Category:Apple Vintage Computers]]