A Technical History of Apple's Operating Systems - Mac OS X Internals

62 Chapter 1 A Technical History of Apple’s Operating Systems
“Gestalt” is originally a German word that means wholeness, shape, or form. In
one of its connotations, it is used to denote a structure or configuration integrated to
form a functional unit in such a way that the properties of the whole are not derivable
by summation of its parts.
1.4.3. GS/OS
As noted earlier, the Apple ][ had a rather long life span. After the release of the
Macintosh in 1984, the Apple ][ still existed as a product. The Apple ][GS was intro-
duced in 1986, almost as a bridge between the old and the new. It was the first and
only 16-bit Apple ][, and had impressive multimedia abilities (the “GS” stood for
graphics and sound). Its notable features included the following.
• A 6502-compatible 37 65C816 processor. The firmware-resident monitor
allowed assembling and disassembling instructions for both processors.
• Support for 24-bit addressing, which allowed memory expansion up to 8
MB. The monitor could handle both 16-bit and 24-bit addresses.
• Two very high-resolution graphics modes: 320×200 with a 16-color palette
and 640×200 with a 4-color palette.
• RGB and NTSC video outputs.
• A 32-voice Ensoniq Digital Oscillator chip that could be driven by firmware
to produce up to 15 musical instruments.
• A mouse-driven, color desktop interface with windows and menus. A
built-in control panel desk accessory allowed the user to set machine parameters
for display, disk drives, processor speed, serial ports, and so on.
• Two standard serial ports that could be used with AppleTalk.
The Apple ][GS had several other additions or improvements over previous
Apple ][ machines.
Apple ProDOS was forked into 8- and 16-bit versions to accommodate the
Apple ][GS. After using ProDOS 16 as the computer’s operating system for a short
37 The user could select either the 1 MHz processor clock speed of the 6502, or a faster 2.8 MHz.