Path: utzoo!attcan!uunet!microsoft!alistair
From: alistair@microsoft.UUCP (Alistair BANKS)
Newsgroups: comp.os.os2.misc
Subject: Re: 1024 cylinder limit in 1.2
Message-ID: <56376@microsoft.UUCP>
Date: 7 Aug 90 18:33:50 GMT
References: <135200001@uxa.cso.uiuc.edu> <135200002@uxa.cso.uiuc.edu>
Reply-To: alistair@microsoft.UUCP (Alistair BANKS)
Organization: Microsoft Corp., Redmond WA
Lines: 31

In article <135200002@uxa.cso.uiuc.edu> twg0214@uxa.cso.uiuc.edu writes:
>
>
>>Most ESDI controllers provide some way of "remapping" of the disk
>>cylinders to less than 1024 by increasing the number of sectors per
>>track logically (inside the drive) to 63. This is transparent to the
>>operating system and works with OS/2 too. I installed an NEC disk with
>>1224 cylinders and a NCL controller successfully using the remapping
>>feature.
>
>This is true and my Ultrastor controller does the remapping, which helps
>with disks up to around 508 Mbytes. For larger disks there is no help.
>Alistair Banks from Microsoft sent me a message today writing that
>the 1024 cylinder limit might be removed in 2.0.

After receiving various mail on this subject & reading the
postings I did some more checking.

Apparently this is a disk driver question, not an OS/2 limit
or HPFS question.  The size that you list sounds like the common
size which is the maximum you can map using existing AT definitions
(1024 cylinders).  If you write a disk driver which determines the
size using a non-standard method, you can get past that.

This has been done by one of the _major_ oems which is about to
release its version of MS OS/2 1.21 - with HPFS support up to
1.2GB.  The point is that you need their disk driver.

Alistair Banks
OS/2 Group
Microsoft