Apple IIGS - Hardware Features

Hardware Features

The Apple IIGS was an innovative computer with many improvements over the older Apple IIe and Apple IIc. It emulated its predecessors by utilizing a custom chip called the Mega II and used the new Western Design Center 65C816 16-bit microprocessor running at 2.8 MHz, which was faster than the 8-bit NMOS 6502 and CMOS 65C02 processors used in earlier Apple II models. Use of the 65C816 allowed the IIGS to address considerably more RAM.

The use of a 2.8 MHz clock was a marketing decision intended to limit the IIgs' performance to a level lower than that of the Macintosh, a decision that had a critical effect on the Apple IIgs' success. In actuality, the 65C816 processor was capable of running at a much higher clock rate.

The IIGS also included enhanced graphics and sound, which led to its name. Its graphics were the best of the Apple II series, with new Super High Resolution video modes. These included a 640×200-pixel mode with 2-bit color and a 320×200-pixel mode with 4-bit color, both of which could select 4 or 16 colors (respectively) from a palette of 4,096 colors. By changing the palette on each scanline, it was possible to display up to 256 colors or more per screen, which was quite commonly seen within games and graphic design software. Through some clever programming, it was possible to display as many as 3,200 colors at once. When first introduced, Apple's user interface known as MouseDesk and the IIGS system Demo were both in black and white only. Users did not see color until an application which took advantage of the new features was launched. Audio was generated by a built-in sound and music synthesizer in the form of the Ensoniq Digital Oscillator Chip (DOC), which had its own dedicated RAM and 32 separate channels of sound. These channels were paired to produce 15 voices, in stereo audio.

The IIGS could support both 5.25-inch and 3.5-inch floppy disks and, like the IIe before it, had several expansion slots. These included seven general-purpose expansion slots compatible with those on the Apple II, II+, and IIe, plus a memory expansion slot that could be used to add up to 8 MB of RAM. The IIGS, like the IIc, also had dedicated ports for external devices. These included a port to attach floppy disk drives, two serial ports for devices such as printers and modems (which could also be used to connect to a LocalTalk network), an Apple Desktop Bus port to connect the keyboard and mouse, and composite and RGB video ports. These ports were associated with the slots, so for example using a card in slot 1 would mean the printer port was disabled.

The IIGS also supported booting from an AppleShare server, via the AppleTalk protocol, over LocalTalk cabling. When the "Apple IIe Workstation Card" was introduced, this capability was given to the IIe. This was over a decade before NetBoot offered the same capability to computers running Mac OS 8 and beyond.