Conference hydra::amiga_v1

>    I need the low level format info for a MiniScribe 8438 (ST506) 32meg
>    drive. I know it has cyls 0-939; but how many heads,
>    tracks,Precomp,etc?
    

I don't have any info on that drive, but since you know the number of cyls
and the capacity, assume 17 sectors (st-506 typical) and calculate the
number of heads:


	capacity ~= 512 * heads * cylinders * sectors

	3200000	 ~= 512 * heads * 940 * 17

	heads = 3.9

	so a reasonable guess is 4 heads.

john

oh, precomp. That's a fairly old drive and most likely requires precomp.

Your safer to turn it on earlier than later since it doesn't hurt where it's
not needed. I'd say try somewhere around cylinder 600.

After format, do a defect map (bad block scan). If it survives this, your
probably safe.


Another good way to find out drive parms is to get a recent copy of 
DiskManager for the IBM PC and run it. It has tables of all the drive
types by manufacturer and model number. Note that this is the only
use I've ever found fo ra PC ;^}

john

    Thanks! I managed to find the info -- through the wonderful Western
    Digital BBS (if you never used it; you can get the formatting info
    on just about any drive in existance there).
    
    I was wrong about the 939 cyls, the correct info is:
    
    615 cyls, 4 heads, 31meg, 26 tracks, precomp at 614 (or something
    like that).
    
    
    The only thing is -- the 2090A prep program won't let me format
    it that way. It refuses to allow 26 tracks per cyl (well, I should
    say it allowed it as an answer, but exited with a "drive not preped"
    error after attempting it, so I ended  up having to use 17.
    This made the drive 20 meg instead of 30; but it is working perfectly.
    The controller had 2 ST506 drives; this miniscribe and a 20meg Seagate
    225. I though perhaps the mixing of these 2 types created the
    situation. Anyone know why it wouldn't prep at 26 tracks?

MFM (ie most ST-506) densities let you get a max of around 18 sectors. Anthing
above that uses RLL encoding which gives you more capacity and slightly
higher data rates (7.5 Mbits/sec as opposed to 5.0 for MFM)


so your drive can handle RLL densities but the 2090(a) is MFM and has picked
17 as it's sector count.

john

       Not wanting to start a new Note, I thought I'd piggyback on this
       one, given it is MINISCRIBE related.
       
       I was fortunate enough to pick up for a reasonable price a working
       40meg 1/2 height MINISCRIBE HD at a flea market.  Unfortunately,
       there is no indication of the power specs (amps being the spec I'm
       missing), so I don't know if my power supply can handle the
       addition of this drive to what I already have connected to it.
       
       Can anyone give me an idea of how many amps this drive - or a 1/2
       height MINISCRIBE in general - would draw?
       
       Thanks in advance.
       
       Art
       

    I do not have the amperage but do have the average power of 9.9 total. 
    I do not have a breakdown for the 5v and 12v.  Hope this helps.
    
    Just for grins hers the rest of what info I have.
    
    MiniScribe 8438
    Formatted Capacity      32.7
    Number of disks            2
    Number of heads            4
    Number of Cyl            615
    Average access time       68ms
    Track ti Track access     15ms
    Average Power            9.9
    Form Factor             3 1/2
    Encoding  Method          RLL
    Sectors per track          26
    Auto park not needed
    
    

       Thanks for the info.  I took a chance anyway and hooked it up to
       my power supply and everything has worked.
       
       Relative to AUTO PARK - do all MINISCRIBES auto park or do you
       have to 'manually' park them??
       
       Thanks
       
       Art
       

    re .7 yes and no.  From the same list:
    
    Auto park  3053   yes
               3085   yes
               3438   no
               3438P  no
               3650   no
               3675   no
               6085   yes
               6128   yes
               8425   shock mounted not needed
               8425F  Shock mounted not needed
               8438   Shock mounted not needed
               8438F  Shock mounted not needed
               9380E  yes
    
    All this info is from an installation manual supplied by hard drives
    international.  
    
           

       Thanks, this helps answer the question.
       
       Art