29 Jan
2011
29 Jan
'11
1:03 a.m.
Tony Duell wrote about hard drives on the Lisa:
Was the HDA a 'stadnard' one for the time?
Surely Apple didn't make that
themselves. Was it, for example, the HDA from an ST412 or something.
The original 5MB Apple "Profile" drive used an HDA from an external
vendor. I'm not sure which one. I've never seen the innards of the
later 10MB Profile.
I've got a prototype of an internal 5MB hard drive for the Lisa, which
was just a repackaging of the 5MB Profile into the appropriate form
factor for internal use. This never shipped as a product.
Having not yet learned from the Twiggy floppy drive fiasco that they
were not competent to design everything in house, Apple made their own
10MB hard drive for the Lisa 2/10 (later Macintosh XL), the Widget. The
HDA was either made by Apple, or by a vendor based on an Apple design.
It doesn't physically resemble any other 5.25-inch HDA I've ever seen.
IWM = 'Integrated Woz Machibne', I believe.
Does anybody know if there's
only one form of it, or several?
Aside from being made in either a DIP or a PLCC, I don't think there are
any significant variants to it.
I was under the impression it was sort-of a
single-chip version of the
logic on the Disk II controller board -- buty how close is it ot that
logic?
It has some added features and modes, but if you don't enable those, it
is mostly compatible with the Disk II controller.
Is it the same state machine, for example?
Probably.
Could you make a replacement using the know schematics
and ROM dump
from a Disk II?
No, because you wouldn't have the extra features and modes.
Apple never provided good documentation on the IWM to customers. Since
it is used in the Apple IIc and Apple IIgs, there is a little bit of
docs in the hardware reference manuals and firmware listings for those
machines. Information is also available in US patent 4,742,448.
The later SWIM disk controller chip was an IWM with an added
IBM-compatible MFM controller. There is even less published
documentation for that, other than US patent 4,916,556.
Actually, it appears that a fair bit of internal docs have leaked out
relatively recently:
ftp://public.asimov.net/pub/apple_II/documentation/hardware/IWM-Device_Spec…
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 198205.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 19820531.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 19831129.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 1984-01.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 19840228.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 19840510.pdf
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM INFO 19840524.pdf
This explains how to switch a SWIM chip between IWM mode and ISM (MFM)
mode, but unfortunately doesn't include the ISM mode documentation:
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
SWIM SPEC 19870929.pdf
This one is not an Apple document, but may be very helpful in
understanding how to use the IWM:
ftp://public.asimov.net/pub/apple_II/documentation/hardware/storage/APPLE 2
IWM PARKER 1994-02.pdf