MFMulation? (Solid-state replacements for MFM drives)

Chuck Guzis cclist at sydex.com
Sun Apr 15 23:54:09 CDT 2007


On 15 Apr 2007 at 19:36, David Comley wrote:

> Exactly. My intended uses are primarily VAX/VMS-based.

Since, as in floppies, you're dealing with raw (unseparated ) data at 
5MHz or thereabouts, recording bit transitions is out of the 
question.  So you'd need some circuitry to both interpret and to 
synthesize not only bits but the various address headers and CRCs.  
IIRC, there wasn't a huge amount of interchangeability between the 
various controller vendors, so you'd need several (selectable) 
routines to handle that.  Then there's the matter of RLL and ARLL--
and synthesizing CRC or ECC results.

It looks pretty daunting to me at first blush, but maybe it's doable 
inexpensively.  Personally, if I had a CP'/M machine, I'd simply work 
up an adapter to interface directly to a Flash card and modify the 
driver software.

Just thinking aloud...

Cheers,
Chuck




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