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Re: it's a FAQ I know, but IIc 5.25" -> anything?
- Subject: Re: it's a FAQ I know, but IIc 5.25" -> anything?
- From: Ed Eastman <noone@nowhere.net>
- Date: Thu, 04 Aug 2005 10:31:33 -0500
- In-reply-to: <08qIe.1314$sW1.1252@newssvr23.news.prodigy.net>
- Newsgroups: comp.sys.apple2
- Organization: University of Nebraska--Lincoln
- References: <1123091977.785547.310510@o13g2000cwo.googlegroups.com> <42F11EDC.C1CCD402@swbell.net> <dcr98k$25su$1@merope.saaf.se> <hjbIe.7329$p%3.33983@typhoon.sonic.net> <dct9b8$313f$1@merope.saaf.se> <08qIe.1314$sW1.1252@newssvr23.news.prodigy.net>
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Bryan Parkoff wrote:
Someone claims
that PC's MFM floppy drive can read Apple II's GCR floppy disk at read only
mode while it converts to create .dsk image. Correct? I don't believe so.
Please clarify more how disk2fdi program works.
The MFM drive doesn't read the CGR bits, it reads the transitions 0 to 1
or 1 to 0. The transition 'generate' an FM pulse that can be detected
by the drive's hardware. These pulses are precisely timed and the bits
between pulses can be extrapolated using software.
Cool, huh?
More info is in the documentation and I can confirm that it works. The
reason the back side does not is due to lack of an index (timing) hole
(reading flippy disks turned front wise) and the fact the 2nd head on a
PC floppy drive is offset by 3 tracks (reading the back side directly).
The PC drive physically can't position the 2nd head over the first
three tracks on the back side.
Thankx,
Ed