On the 20/06/96, Rod waffled to Dieter..

 Hello Rod,

 DM> disk mangler is different. It's a software
 DM> rather than a hardware/firmware implementation.
 
 DM> In it's time, it worked remarkably well. I had installed
 DM> it ion several PC's, and none ever caused me any grief.

 RS> The main irritation with it compared with LBA is where you want to
 RS> say move to OS/2 from a DOS/Win config etc. LBA is rather cleaner.

 Indeed it is - that's why I said in the past - it was OK with
 Win3.0/3.11, and DOS prior to that. Then again, there wasn't
 that much call for the large HDD's we seem to need now.

 Wasn't there a 30 or 40meg limit in the days of DOS-only systems?
 Could have been a limitation of the DOS itself, and DM was used
 to partition the HDD to get around that.

 RS> The main downside with going that route is that it can fang you if
 RS> you have a >528MB drive, have upgraded your motherboard to one with
 RS> LBA support, and then you want to step back to your old motherboard
 RS> without LBA support for some reason like the new MB has some warts
 RS> etc.

 I wouldn't use DM myself these days - there are more elegant
 solutions.

 DM> Not necessarily, although the bulk of
 DM> the 4-HDD controllers seem to be VLB based.

 RS> No real need to have it all on one card, any even pure IDE paddle card
 RS> which can be jumpered to the secondary etc IDE port stuff is fine.

 If you have one lying around and still have the sheet of paper
 and shows the jumper settings :-]
 
 DM> I'm basically in the same boat as you, viz the CD ROM drive. Currently
 DM> I've been using a yum-cha audio card, with the audio bits disabled, to
 DM> access the CD ROM. But it seems to conflict occasionally with OS/2 and
 DM> perhaps the MediaVision PAS card, leaving the system unstable.

 RS> Why not try a simple ISA IDE paddle card which can be
 RS> jumpered to the secondary IDE port address etc. Most can be.
 
 Indeed they can - if I can find the settings. Although there is
 usually one jumper on the board.

 BL> Can't I enable LBA for the big drive but access
 BL> the small one non-LBA? I back up to the small drive.
 
 DM> Yes, you can do that - LBA is implemented on a per-drive basis
 
 DM> Some of the newer BIOS's also sport a setting called LARGe, in addition
 DM> to LBA and standard modes. I have no idea if this is an alternative
 DM> method of accessing the entire HDD space. Maybe Rod would know.

 RS> LARGE is a different way of getting around the 1024/16 limit, allowing
 RS> more than 16 heads, but the BIOS translates that into a cylinder/head
 RS> combination of >1024 cylinders and <= 16 heads, usually by doubling
 RS> the heads and halving the cylinders. So DOS and the bios operates in
 RS> terms of CHS values of 16 heads and that is
 RS> translated by the bios into >1024 cylinders and <=16 heads before the
 RS> command goes out on the cable in CHS values to the drive itself.

 RS> This one is only relevant for OSs which use the BIOS for the
 RS> drive. Modern stuff like OS/2 which replaces the BIOS with its
 RS> own code once its properly booted has to be able to do that CHS
 RS> translation itself, and LBA is a rather cleaner route with those.

 Ta for the explanation. BIOS help seems to be somewhat lacking
 in either the supplied M/B booklet or on-screen help.

 What about Win95 ? Is it still stuck with the 540k limitation if
 LBA or LARGE is not enabled ?

 Dieter
 

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