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Received: from relay1.geis.com (relay1.geis.com [192.77.188.2]) by nacm.com (8.6.10/8.6.9) with ESMTP id SAA04859 for <executor@nacm.com>; Thu, 18 May 1995 18:06:28 -0700 From: g.sightler@genie.geis.com Received: by relay1.geis.com (1.37.109.11/15.6) id AA299105581; Fri, 19 May 1995 01:06:21 GMT Message-Id: <199505190106.AA299105581@relay1.geis.com> Date: Fri, 19 May 95 00:26:00 UTC To: executor@nacm.com Subject: Reading MAC 800K disks. X-Genie-Id: 1251800 X-Genie-From: G.SIGHTLER Sender: owner-paper@nacm.com Precedence: bulk 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 |||||