Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!microsoft!brianw
From: brianw@microsoft.UUCP (Brian Willoughby)
Newsgroups: comp.sys.apple
Subject: Re: I*M M*-D*S disks and AMI*A disks
Message-ID: <8075@microsoft.UUCP>
Date: 17 Oct 89 03:36:53 GMT
References: <507@fawlty.towers.oz>
Reply-To: brianw@microsoft.UUCP (Brian Willoughby)
Organization: Microsoft Corp., Redmond WA
Lines: 37

In article <507@fawlty.towers.oz> johnmac@fawlty.towers.oz (John MacLean) writes:
>Is it true that 720K 3.5" IBM disks use a different physical low level
>format and so *cannot* be read by 800K Apple drives?

I *think* that's true.

>I believe the MACs superdrive (1.44M 3.5 for reading I*M disks etc)
>requires a new IWM chip; is this true?

It's called the SWIM - Super Woz Integrated Machine.

>If this fails is the IWM chip socketed on the new GS?

I wish Apple would let us (owners of older Apple equipment) purchase SWIM
chips, but they are understandably guarding their technology.  I would
quickly buy the first external, SmartPort SuperDrive I could get my hands
on, if only Apple would make one.  I would write my own drivers (damnit),
and even resort to building a cabinet for an internal drive, but I don't
think that is a solution yet.

>I also read under COMP.SYS.AM*GA that the thier 3.5" can read 2 of the 5
>variable speeds on an Apple 3.5" (they use a constant speed). This would
>seem to imply that an Apple 3.5" is capable of directly reading their
>disks. Is this the case? Does anyone have any low level code around?
>Note that A*IGA disks use 24? bytes of overhead per 512 byte block!

According to the Inside Mac references, all 800K drives adjust thier own
speed.  Based on that info, I don't see how you could force a different
speed on a particular track.

>Please post knowledge for all, I am sure others will be interested ...

Brian Willoughby
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