RE: [expert] OT: harddrive flashback

[Himebaugh, Jon, CON, OASD(HA)/TMA]

Doesn't this mean Non Return to Zero Inverted? I read a really good
explanation to what this is once but alas I can only keep so much in main
memory. :-))

Jon H

-----Original Message-----
From: Michael R. Batchelor [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 27, 2000 7:37 PM
To: [EMAIL PROTECTED]
Subject: Re: [expert] OT: harddrive flashback


MFM is Modified Frequency Modulation
RLL is Run Length Limited

They are descriptions of how the bias current is manipulated to encode
the 0's and 1's on the physical media. You were *SUPPOSED* to use MFM
controllers with MFM drives and RLL controllers *ONLY* with RLL
certified drives, but a lot of people pushed it because using a 20MB MFM
drive with an RLL controller got you 30MB of storage. Sort of the same
crowd who would be overclocking today. (What are you looking at?! You
don't think *I* pushed the envelope back then do you?)

If you want a real education about how drives work (even today) track
and learn what NRZI means? (Hint:This is a challenge.)



>Hey, speaking of the ORIGINAL topic here.... anyone remember MFM hard
>drives??? I am subscribed to a list from Hitechcafe.com and this

[...]
>*shudder* I remember MFM hard drives. Boy those were the days... had
>to be sure you had an RLL hard drive with the MFM controller... or
>was it an MFM hard drive with an RLL controller??? I recall that you
>could essentially increase your drive space by about 50% by using RLL
>with MFM controller or vice versa... :-)