🚀 go-pugleaf

In article <a1ik13w164w@graphics.rent.com> warrenl@graphics.rent.com (Warren Lieuallen) writes:
>
>   I've got an RLL HD controller (and an RLL hard drive, naturally).
>I'd like to buy another hard drive to add to my system, and have
>found a good deal, but's it's an MFM drive.  The seller suggested
>that I could simply hook the drive up to my RLL controler and
>voila, it would now be an RLL drive, instantly upgraded to 7.5
>Meg/sec (up from MFM's 5 Meg/sec).
>   Is this true?  Can MFM and RLL drives be hooked up inter-
>changeably?  If so, what's the difference between my ST138R and
>the MFM version ST138?
>   Many thanks!

Yes you can hook an MFM drive up to an RLL controller, and it 
*should* work...but doing so is like using a 3.5" DD diskette formated
for HD, it *should* work but depends on the quality of the diskette (media)
and the drive.

Generally an RLL rated drive has been designed and tested to more rigid
standards since the data *is* stored more densely on the RLL drive
(17 sectors/track MFM vs 26 sectors/track RLL). For example with the
same drive (an Toshiba MK134R) formatted for MFM will give you ~44MB
capacity, formatted for RLL it will have a capacity of ~68MB. So with 
an RLL drive you get higher capacity and higher transfer rates...unfortunately
RLL is slightly more prone to errors...

To maximize the probability of successfully using an MFM drive on an RLL controller
1) use a high quality MFM drive - generally drives with voice coil head actuators
   and thin film sputtered media are a much better choice for this...stepper
   motor head actuators & oxide media are generally NOT recommended for this
   type of service...If you want to use a MFM drive with stepper motor & oxide
   media (most of the low end drives, esp. Segate) in RLL service, well, "you pays
   your money and you takes your chances..."

2) Make sure your controller cables are in excellent condition (connectors & wires)
   and be careful with the routing to avoid noise and crosstalk.

good luck...

John

+--------------------------------------------------------------------+
| John Burton                                                        |
| G & A Technical Software                                           |
| jcburt@gatsibm.larc.nasa.gov                                       |
| jcburt@cs.wm.edu                                                   |
|                                                                    |
| Disclaimer: Hey, what can I say...These are *my* views, not those  |
|             of anyone else, be they employer, school, or government|
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