Question:
What are the maximum number of partitions?
Answer:
A question has been raised about the Apple IIe and maximum number of
partitions considering each floppy drive controller card (3.5" or 5.25")
takes away two and the RAM disk in 3,2 takes away one. Normally, each of the
7 Apple IIe slots can have 2 drives associated with it. With one floppy drive
controller card in slot 6 and one RAM disk, out of the 14 possibilities there
is room to allocate eleven: S1,D1; S1,D2; S2,D1; S2,D2; S3,D1; S4,D1; S4,D2;
S5,D1; S5,D2; S7,D1; S7,D2
This discussion should also note that a hard drive, whatever total size, can
be initialized and partitioned for the Apple IIe into several/many 32
megabyte (max) ProDOS volumes, sometimes called partitons. It is usually more
useful to refer to these as volumes, since that is what ProDOS 8 version
2.0.3 deals with when it makes slot/drive assignments at boot time. Why 32
megabytes maximum? That's because 32 megabytes contains 64k (65,536) of
512-byte blocks and the 8-bit 65C02 CPU can't address more than 64k without
bank-switching or whatever.
ProDOS 8 version 2.0.3 is looking for block devices (drives) when it scans
the slots at boot time so that when it finds a block device with more than
two volumes it can assign the extra volumes to other unused slot/drive
locations. For purposes of this scan, the following don't constitute block
devices: mouse interface card, sound card, serial or parallel printer
interface card, modem card, scanner interface card, digitizer board,
accelerator card, etc. The slots occupied with cards of this type are
therefore free to be used in ProDOS's volume slot & drive assignment process
where ProDOS is said to be "mapping" the volumes to other slots & drives.
One other thought has to do with how a hard drive is connected to and boots
the Apple IIe. This involves an attached interface/controller card of some
sort in one of the empty slots. The Apple IIe ROMs at switch on look for a
block device from which to locate & run the file named ProDOS. The process
starts with the highest numbered slot (#7) and works its way down to slot #1.
If booting from the hard drive is desired, then the card should be placed in
a slot numbered higher than the slot in which the floppy drive's card resides.
When you have a SCSI hard drive, you need one of these cards to interface it
with the Apple IIe: Apple Rev C or High-Speed SCSI card; CMS SCSI controller
card (not totally standards compliant); RAMFast SCSI card. Other hard drives
followed the standard used on IBM computers (MFM, RLL, IDE, etc) and had
interface/controller cards that were unique to them. Some examples were the
drives from Applied Engineering, Ingenuity, First Class Peripherals, Focus,
etc. The most versatile standard is probably SCSI, since other devices can be
daisy-chained on the SCSI bus using the one interface/controller card.
