NtSetIRTimer
Set → NTSTATUS
NtSetIRTimer is a Windows NT kernel system call, in the Set category, returning NTSTATUS. Its syscall number is not the same on every Windows release: across the 40 version-and-architecture pairs recorded here it takes 21 distinct values, from 0x0040 to 0x01A4.
The number is an index into the system service table of one particular build, not a stable identifier, so it is not portable between Windows versions or between x64 and x86. The table below gives the value recorded for each.
Numbers across OS versions (40)
| OS Version | Architecture | Number |
|---|---|---|
| Windows 10 1507 | x86 | 0x0042 (66) |
| Windows 10 1507 | x64 | 0x0178 (376) |
| Windows 10 1511 | x86 | 0x0042 (66) |
| Windows 10 1511 | x64 | 0x017B (379) |
| Windows 10 1607 | x86 | 0x0042 (66) |
| Windows 10 1607 | x64 | 0x0181 (385) |
| Windows 10 1703 | x86 | 0x0042 (66) |
| Windows 10 1703 | x64 | 0x0187 (391) |
| Windows 10 1709 | x64 | 0x018A (394) |
| Windows 10 1709 | x86 | 0x0043 (67) |
| Windows 10 1803 | x86 | 0x0043 (67) |
| Windows 10 1803 | x64 | 0x018C (396) |
| Windows 10 1809 | x64 | 0x018D (397) |
| Windows 10 1809 | x86 | 0x0043 (67) |
| Windows 10 1903 | x64 | 0x018E (398) |
| Windows 10 1903 | x86 | 0x0043 (67) |
| Windows 10 1909 | x86 | 0x0043 (67) |
| Windows 10 1909 | x64 | 0x018E (398) |
| Windows 10 2004 | x86 | 0x0043 (67) |
| Windows 10 2004 | x64 | 0x0194 (404) |
| Windows 10 20H2 | x64 | 0x0194 (404) |
| Windows 10 20H2 | x86 | 0x0043 (67) |
| Windows 10 21H1 | x64 | 0x0194 (404) |
| Windows 10 21H1 | x86 | 0x0043 (67) |
| Windows 10 21H2 | x64 | 0x0196 (406) |
| Windows 10 21H2 | x86 | 0x0043 (67) |
| Windows 10 22H2 | x86 | 0x0043 (67) |
| Windows 10 22H2 | x64 | 0x0196 (406) |
| Windows 11 and Server 11 21H2 | x64 | 0x019E (414) |
| Windows 11 and Server 11 22H2 | x64 | 0x01A1 (417) |
| Windows 11 and Server 11 23H2 | x64 | 0x01A1 (417) |
| Windows 11 and Server 11 24H2 | x64 | 0x01A4 (420) |
| Windows 11 and Server 11 25H2 | x64 | 0x01A4 (420) |
| Windows 11 and Server Server 2022 | x64 | 0x019C (412) |
| Windows 11 and Server Server 2025 | x64 | 0x01A4 (420) |
| Windows 11 and Server Server 23H2 | x64 | 0x01A3 (419) |
| Windows 8 8.0 | x86 | 0x0040 (64) |
| Windows 8 8.0 | x64 | 0x016E (366) |
| Windows 8 8.1 | x86 | 0x0041 (65) |
| Windows 8 8.1 | x64 | 0x0171 (369) |