To support the old Apple II mode on the Apple IIGS, system disks have P8, or
ProDOS/8, as it is a version of ProDOS 1.1.1 made especially for Apple IIGS,
although ProDOS/8 works on an Apple IIe or Apple IIc.
ProDOS/8 handles the following Apple IIGS capabilites, features and operating
modes:
- ProDOS/8 accepts system calls from applications running in 8-bit mode only.
- ProDOS/8 accepts system calls from the lowest 64K of memory only.
- ProDOS/8 uses a simple global page bit map.
- ProDOS/8 maintains a section of memory, which can be accessed directly,
that
contains system global variables such as date and time, system level, and
I/O
buffer addresses.
- ProDOS/8 reads the Apple IIGS clock rather than the ThunderClock.
On the Apple IIGS, ProDOS and ProDOS/16 are designed to the run in tandem, as
a package. ProDOS/8 is provided to maintain compatibility with ProDOS v1.1.1.
In normal situations, you need not be concerned with which operating system
is functioning; ProDOS/8 is automatically loaded if you run an application
designed to run under ProDOS 1.1.1 or versions earlier.