Windows 2000 provides support for single or multiple
Central Processing Units (CPU); however, if you originally installed Windows
2000 on a computer with a single CPU, the hardware abstraction layer (HAL) on
your computer must be updated for your computer to recognize and use multiple
CPUs. This article describes how to add support for multiple processors in
Windows 2000. In Microsoft Windows NT 4.0, you can use the Uptomp.exe tool to
add support for multiple CPUs. The Uptomp.exe tool is not used in Windows 2000,
instead, you can use Device Manager to make these changes. Note that before you
change the computer type, contact your computer manufacturer to determine if
there is a vendor-specific HAL that you should use instead of the standard HAL
that is included in Windows 2000.
Installing Support for Multiple CPUs
- Click Start, point to Settings, point to Control Panel, and then click System.
- Click the Hardware tab, and then click Device Manager.
- Double-click to expand the Computer branch. Note the type of support that you currently
- Double-click the computer type that is listed under the Computer branch, click the Drivers tab, click Update Driver, and then click Next.
- Click Display a list of known drivers for this
device, and then click Show all hardware of this device
- Click the appropriate computer type (do not change from
non-ACPI to ACPI computer types), click Next, and then click Finish.
The following table lists and describes each HAL.
ACPI MultiProc Use for a multiple-processor ACPI computer
ACPI UniProc Use for a ACPI multiple-processor board but with a
single processor installed
Advanced Use for a single processor motherboard with single
Configuration processor ACPI computer
Power Interface PC
Compaq Systempro Use for a Compaq Systempro computer
MPS Uniprocessor PC Use on non-ACPI computers dual processor motherboard
with a single processor installed
MPS Multiproc PC Non-ACPI computers with a dual processor running
Standard PC Any Standard PC, non-ACPI, or non-MPS. Could be a 386,
486, Pentium, Pentium II, or Pentium III
with C-Step i486
: You can use this procedure only to upgrade from a
single-processor HAL to a multiple-processor HAL. If you use this procedure to
change from a standard HAL to an ACPI HAL (for example, after a BIOS upgrade)
or vice-versa, unexpected results may occur, including an inability to boot the
For additional information how to troubleshoot Windows 2000
HAL issues, click the article number below to view the article in the Microsoft
Troubleshooting Windows 2000 Hardware Abstraction Layer Issues