Windows NT 4.0 build 1381.133

4.0.1381.133
	Build of Windows NT 4.0
OS family	Windows NT
Version number	4.0
Build number	1381
Build revision	133
Architecture	x86 (PC/AT, PC-98), Alpha
Compiled on	1998-10-16
SKUs
	Server; Workstation
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Windows NT 4.0 build 1381.133 is the official Service Pack 4 release of Windows NT 4.0, which was released on 25 October 1998. This service pack needs to be installed if setting up a dual boot with Windows 2000.

Changes[edit | edit source]

This service pack uses a new installer, which is also used for Windows 98 SP1 and service packs for Windows 2000 until SP2.
ACPI capability has been added. On capable hardware, Windows NT is now able to use ACPI functions to turn off the computer.

SGI OEM version[edit | edit source]

A modified Silicon Graphics (SGI) OEM release of this build was shipped alongside the SGI Visual Workstation 320/540 computers,^[1] featuring various updated binaries such as hardware abstraction layers (HALs) needed to allow the operating system to function on a non-standard x86 environment due to the systems' usage of the ARC specification. The Service Pack 4 installer included on the disc has had its UPDATE.INF directive file slightly altered to prevent newer files from the I386 source file directory from being overwritten by the original SP4 counterparts.

The x86 ARC versions of ntldr and setupldr (labeled ARCLDR.EXE and ARCSETUP.EXE) are forked from a Windows 2000 development build. Various files intended for standard x86 systems (ntldr, ntdetect.com setupldr.bin, HALs) from the RTM are present but unused; indeed, the txtsetup.sif directive file was modified to exclude all binaries not required for installation on the aforementioned systems, like BIOS-based boot loader components and HALs for other systems. A USB driver (SGIUSB00.SYS) is also present, containing code copied from the Windows 2000 USB stack; only a bare minimum subset of hardware, specifically USB keyboards and mice, are supported by this driver.