lotus

previous page: 04.09.  I need an Enhanced BIOS to access >504MB. How do I get one?
  
page up: Enhanced IDE/Fast-ATA/ATA-2 FAQ
  
next page: 04.11.  I heard that Win95 provides support for large IDE disks.

04.10. Can I use a large harddisk with OSs other than DOS/Windows?




Description

This item is from the Yet Another Enhanced IDE/Fast-ATA/ATA-2 FAQ, by John Wehman and Peter den Haan with numerous contributions by others. (v1.92).

04.10. Can I use a large harddisk with OSs other than DOS/Windows?

Using a large harddisk is usually no big problem, even if you don't have an Enhanced BIOS. However, some OSs don't understand translation, which makes the combination with DOS, Windows and Win95 problematic.

With operating systems such as NetWare, Unix, Win/NT and OS/2, the only thing you need to use large ATA disks is a BIOS that allows more than 1024 cylinders in the drive type setup. There is one caveat though: the BIOS is still used to boot the operating system, so you will have to ensure that everything necessary to get the OS running in the first place resides below cylinder 1024. Remember that if you have an Enhanced BIOS, drives up to 8GB will appear to have no more than 1024 cylinders, so in those cases these boot restrictions are removed.

Once running, these operating systems use their own software to control the disks (Win95 also does this, but has a special position; see below). That way, they are not subject to the BIOS' restrictions such as the capacity limit. Unfortunately, this also means that if you have a translating EBIOS or software driver, the OS has to be aware of the translation scheme used, or conflicts will arise between the operating system and DOS/Win/Win95. If you can set up partitions so that all DOS and boot partitions reside below the first 1024 cylinders (504MB), you can avoid translation altogether and all the hassles with it.

Older operating systems don't understand translation at all. Newer ones (OS/2 3.x, Linux 1.2 or better, Win95, SCO 5.0.x) will handle standard translation schemes out of the box, but not always those employed by some software drivers (EZDrive, Disk Manager v6.x or older). In the case of DM 6, fixes or updates are available for some operating systems (see above).

Novell has a NetWare driver IDE.DSK version 3.0 dated September 2, 1994. This version of the driver uses the Identify Device ATA command to get the drive parameters and ignores the BIOS parameters. This means that Novell now works with big IDE drives.

A final remark: OS/2 enforces DOS compatibility for FAT partitions. That means that without an Enhanced BIOS, only HPFS partitions can extend beyond cylinder 1024.

 

Continue to:













TOP
previous page: 04.09.  I need an Enhanced BIOS to access >504MB. How do I get one?
  
page up: Enhanced IDE/Fast-ATA/ATA-2 FAQ
  
next page: 04.11.  I heard that Win95 provides support for large IDE disks.