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5

Both the DFS and the ADFS did indeed reserve memory for themselves at startup, increasing PAGE; this memory was used to hold the current catalogue and other bookkeeping. For adapting existing tape software two observations are helpful: almost nothing on the BBC was a multiload; and you can turf the [A]DFS out of memory if you don't intend to use it again. ...


4

It is rather straight-forward, technically speaking, to share both 3.5" floppy disks and their image files between a Classic Mac (e.g. MacOS System 7) and an Apple IIgs. This because both systems support ProDOS floppies and HFS floppies (in GS/OS), and both systems support image files for 800KB disks using DiskCopy 4.2. So, that solves most needs back ...


8

In reference to the comment "Any idea how the IIGS implements those Disk II motor detectors?" There's this Technical Note #68: Tips for I/O Expansion Slot Card Design. It says: On the Apple IIGS, the Mega II select signal (/M2SEL) is used as the enable to the slower, 1 MHz side of the system. It goes active (low) whenever the 1 MHz side of RAM or ...


16

From the Apple IIgs Hardware Reference, Second Edition, pages 22-24: Figure 2-6 - Speed register at SC036 Table 2-2 - Bits set in the Speed register [...] Bits 0-3† Value 1 Description Disk II motor-on address detectors: To retain Apple II peripheral compatibility, the motor-on detectors change the system speed to 1.024 MHz whenever a Disk II motor-on ...


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