=== Miniscribe disk drive infos ===

[Tony Duell]

> Yes, most RLL drives can be formatted to lower capacity and used on a MFM=20
> controller, but some aren't reliable when used that way. I don't know which=
> =20
> are.

How can this be? With this sort of disk interface, the critical thing is 
the timing between given edges (say rising edges) of the pulses on the 
data line (the pulse width is not generally important).  And I was under 
the impressing that the set of times possible for the MFM interface was a 
subset of the times for the RLL interface. And that a pulse stream from 
the MFM interface was a possible pulse stream (albeit with a different 
meaning) from the RLL interface too.

Sicne these ST506/ST412 drives are dumb devices (they don't try to 
interpret the data pulses, they just record them and reproduce them), I 
don't see how a drive can do RLL but not MFM.

-tony