Re: Using 3.5" IDE drive with AIIe

[david@uow.edu.au (David Wilson)]

pausch@saaf.se (Paul Schlyter) writes:
>The problem is that ProDOS most certainly don't have built-in support
>for homemade IDE cards (I interpreted your "somehow" as if you wanted
>to build your own IDE adapter for the Apple II).  There's much more
>to adapting an OS to a new hardware device than just checking the
>supported partition sizes....

ProDOS will support any card that contains ProDOS Block Interface code
in its onboard CnXX ROM. This is how SCSI & RAMdisk cards work.

>Also, "partitioning" can be done in many ways -- it's merely a
>software convention of splitting up the HD into several logical
>areas.  Does ProDOS support the PC conventions for partitioning
>harddisks, or does ProDOS use its own conventions?  When the 5 MByte
>Corvus harddisks first appeared, it was usually partitioned into
>zillions of Apple DOS partitions, each 140 KBytes large, to mimic an
>Apple II DOS floppy -- that partitioning was certianly obtained in a
>way incompatible with the partitioning of most IDE harddisks today.

The Apple SCSI cards implement the same partition scheme as used by
the Macintosh.

All ProDOS can do is ask the card to read or write a block numbered
0..65535 from one of 4 "drives" supported by the card (provided it
is in slot 5 - otherwise only 2 "drives") or format or check status
(write protected etc). If the onboard firmware wants to map all 4
drives to one physical device it is free to do so giving 128MB in 4
32MB chunks.

If it wants to have a more complicated partitioning scheme that will
work as well.

If you want more than 4 x 32MB then you need ProDOS 8 v2.x and a
more complicated ROM with a Smartport interface - this can support
up to 13 x 32MB.

I have written such drivers - my ROMdisk card supports 1..4 64KB ROMs
and can be partitioned into any combination of 1 to 4x 64/128/192/256
sized disks with a total size not exceeding 256KB. eg 64+128+64 is valid.
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia