ISA MFM disk controllers

[Dave McGuire]

On Jun 19, 2009, at 10:40 PM, Mr Ian Primus wrote:
> Anyone remember the difference between the various Western Digital  
> MFM disk controllers? I've got a few in front of me right now, and  
> I'm trying to figure out which would be the best for this Compaq  
> Portable 286.
>
> I've got the good ol' WD1002A-WX1, and what looks to be the bigger  
> verison, the WD1002S-WX2, then another, even longer card, the one  
> that came stock with the Compaq, the WD1015-PL03.
>
> Now, here's the dilemma. The stock card won't respond to the usual  
> debug commands - they just freeze the computer. The original 20mb 3  
> 1/2" Miniscribe hard drive is dead (won't even spin). I am going to  
> replace it with a similar 3 1/2" form factor drive - the NEC D3142.  
> (43mb! Woo!) I already got the drive formatted and working on the  
> small WD1002A-WX1 card, but it's been a while since I worked with  
> MFM controllers - and I seem to remember the WD1002S-WX2 being  
> faster or something.

   Wow.  I used to know *all* of those part numbers, have been  
shaking my head trying to jog my memory for the past few minutes, but  
it seems that info is just gone. :-(

> Also, I don't remember the calculations for optimum interleave, I  
> used 3, since that was the default....

   You can use something like Spinrite to discover the proper  
interleave for a disk subsystem, and it will even format in-place  
(track at a time) and preserve data.  I used it all the time, it was  
quite good.

              -Dave

-- 
Dave McGuire
Port Charlotte, FL