Questions about RLL controllers

[Kevin Tissot]

skrenta at eecs.nwu.edu (Richard Skrenta) writes:

> ....  I've heard that switching to
> an RLL controller could boost the available space on each drive by 50%
> as well as increasing the data transfer rate.

True.

> Are there any dangers associated with using an RLL controller on drives
> only certified for MFM?  Could the controller damage the drive in any
> way, or is it just a matter of mapping a few more bad tracks during the
> format?

The controller should not damage the drive in any way. Your data, however,
may not be so lucky. Using an RLL controller on an MFM drive may lead to
data loss since the RLL format places higher demands on the disk media than
the MFM format does. Some drives can handle this and some can't. My guess
would be that your Miniscribe disk might work but your Seagate will
probably fail miserably. 

> Also, where does the extra space come from?  Do RLL controllers increase
> the sectors per track or the number of tracks? 

Most PC RLL controllers increase the sectors/track from 17 to 26, thus
increasing both the data storage capacity and the raw transfer rate from
the media to the disk head. Whether or not this increases the transfer rate
to your PC depends on the disk controller you choose. A good controller
which supports 1:1 interleave will give the best improvement.

-- 
Kevin Tissot                                     / /~~~\ \
Nicolet Audiodiagnostics                        /|/ O O \|\
Madison, Wisconsin                              \|\  _  /|/
...uwvax!astroatc!nicmad!nicaud!tissot             \___/