OS Select For DRAM > 64MB from The Tech ARP BIOS Guide

OS Select For DRAM 64MB from The Tech ARP BIOS Guide

OS Select For DRAM > 64MB

Common Options : OS/2, Non-OS/2n-OS/2

 

Quick Review of OS Select For DRAM > 64MB

The OS Select For DRAM > 64MB BIOS feature is designed to correct the memory size detection problem for OS/2 systems that have more than 64 MB of system memory.

If you are using an older version of the IBM OS/2 operating system, you should select OS/2.

If you are using the IBM OS/2 Warp v4.0111 or higher operating system, you should select Non-OS/2.

If you are using an older version of the IBM OS/2 operating system but have already installed all the relevant IBM FixPaks, you should select Non-OS/2.

Users of non-OS/2 operating systems (like Microsoft Windows XP) should select the Non-OS/2 option.

 

Details of OS Select For DRAM > 64MB

Older versions of IBM’s OS/2 operating system use the BIOS function Int15 [AX=E801] to detect the size of installed system memory. Microsoft Windows, on the other hand, uses the BIOS function Int15 [EAX=0000E820].

However, the Int15 [AX=E801] function was later scrapped as not ACPI-compliant. As a result, OS/2 cannot detect the correct size of system memory if more than 64 MB of memory is installed. Microsoft Windows isn’t affected because the BIOS function it uses is ACPI-compliant.

The OS Select For DRAM > 64MB BIOS feature is designed to correct the memory size detection problem for OS/2 systems that have more than 64 MB of system memory.

If you are running an old, unpatched version of OS/2, you must select the OS/2 option. But please note that this is only true for older versions of OS/2 that haven’t been upgraded using IBM’s FixPaks.

Starting with the OS/2 Warp v4.0111, IBM changed the OS/2 kernel to start using Int15 [EAX=0000E820] to detect the size of installed system memory. the memory management system to the more conventional method. IBM also issued FixPaks to address this issue with older versions of OS/2.

Therefore, if you are using OS/2 Warp v4.0111 or higher, you should select Non-OS/2 instead. You should also select Non-OS/2 if you have upgraded an older version of OS/2 with the FixPaks that IBM have been releasing over the years.

If you select the OS/2 option with a newer (v4.0111 or higher) or updated version of OS/2, it will cause erroneous memory detection. For example, if you have 64 MB of memory, it may only register as 16 MB. Or if you have more than 64 MB of memory, it may register as only 64 MB of memory.

Users of non-OS/2 operating systems (like Microsoft Windows or Linux) should select the Non-OS/2 option. Doing otherwise will cause memory errors if you have more than 64 MB of memory in your system.

In conclusion :-

  • If you are using an older version of the IBM OS/2 operating system, you should select OS/2.
  • If you are using the IBM OS/2 Warp v4.0111 or higher operating system, you should select Non-OS/2.
  • If you are using an older version of the IBM OS/2 operating system but have already installed all the relevant IBM FixPaks, you should select Non-OS/2.
  • Users of non-OS/2 operating systems (like Microsoft Windows XP) should select the Non-OS/2 option.

Go Back To > The Tech ARP BIOS Guide | Home

 

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