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Reading MAC 800K disks.



Ernst,
 
 >>>>>> "Jesse" == g sightler <g.sightler@genie.geis.com> writes:
 >>
 >>    Jesse> Actually, it would be possible to do this without the MAC
 >>    Jesse> floppy drive, if someone was willing to put the many hours
 >>    Jesse> necessary into it.  <g> Seriously, it is VERY timing
 >>    Jesse> sensitive (which rules out the possibility of running it
 >>    Jesse> under any mulitasking OS), but it can be done with the
 >>    Jesse> right amound of hacking/patience.
 >>
 >>    Jesse> In fact, the early MAC emulators for the Amiga did this
 >>    Jesse> rather well (of course, they had to shut off multitasking
 >>    Jesse> to do it :).
 >>
 >> Clifford T. Matthews replied:
 >>
 >>Well it certainly won't happen between now and when 2.0 comes out.
 >>Even then I'm not sure that the PC has the same sort of control over
 >>the floppy disk that the Amigas did.  After 2.0 comes out we'd
 >>probably be willing to pay some $$ to get this functionality, but I'd
 >>also guess that just a simple program to read 800k Mac disks on a PC
 >>would also generate some revenue, which then begs the question "if
 >>it's doable, why hasn't someone done it?"  Specifically, why hasn't
 >>someone written a program for the PC which reads an 800k formatted
 >>floppy (writing is much less important).
 >>
 >Had the same thoughts and had someone look into the SWIM chip of Mac's
 >(Super Woz Integrated Machine) - handles diskette I/O. It is IMPOSSIBLE to
 >do this on a PC without hardware. The 800K Mac drives (and all drives
 >since then) use a variable spindle speed of the disk drive's motor. This
 >motor on PC drives can only be switched on or off. There is no software
 >control over its speed. When the speed cannot be controlled there is no
 >way to decipher the information that comes from the controller.
 
Actually, the Amiga was unable to change the speed of the drive's motor
either.  This is why it was such a TIMING sensitive thing (and a very
difficult hack to program, from what I've been told :).
 
Although, as we have now been told by others here, it still wouldn't be
possible on a PC (they don't give as much control over the floppy as the
Amiga).
 
||||| Jesse D. Sightler |||||