SYSTEM_INFO info  Overview  Group

The SYSTEM_INFO structure contains information about the current computer system. This includes the architecture and type of the processor, the number of processors in the system, the page size, and other such information.

typedef struct _SYSTEM_INFO { // sinf 

    union { 

        DWORD  dwOemId; 

        struct { 

            WORD wProcessorArchitecture; 

            WORD wReserved; 

        }; 

    }; 

    DWORD  dwPageSize; 

    LPVOID lpMinimumApplicationAddress; 

    LPVOID lpMaximumApplicationAddress; 

    DWORD  dwActiveProcessorMask; 

    DWORD  dwNumberOfProcessors; 

    DWORD  dwProcessorType; 

    DWORD  dwAllocationGranularity; 

    WORD  wProcessorLevel; 

    WORD  wProcessorRevision; 

} SYSTEM_INFO; 

 

Members

dwOemId

An obsolete member that is retained for compatibility with previous versions of Windows NT. Beginning with Windows NT 3.51 and the initial release of Windows 95, use the wProcessorArchitecture branch of the union.

Windows 95: The system always sets this member to zero, the value defined for PROCESSOR_ARCHITECTURE_INTEL.

wProcessorArchitecture

Specifies the system’s processor architecture. This value can be one of the following values:

Value
PROCESSOR_ARCHITECTURE_INTEL
Windows NT only: PROCESSOR_ARCHITECTURE_MIPS
Windows NT only: PROCESSOR_ARCHITECTURE_ALPHA
Windows NT only: PROCESSOR_ARCHITECTURE_PPC
Windows NT only: PROCESSOR_ARCHITECTURE_UNKNOWN

wReserved

Reserved for future use.

dwPageSize

Specifies the page size and the granularity of page protection and commitment. This is the page size used by the VirtualAlloc function.

lpMinimumApplicationAddress

Pointer to the lowest memory address accessible to applications and dynamic-link libraries (DLLs).

lpMaximumApplicationAddress

Pointer to the highest memory address accessible to applications and DLLs.

dwActiveProcessorMask

Specifies a mask representing the set of processors configured into the system. Bit 0 is processor 0; bit 31 is processor 31.

dwNumberOfProcessors

Specifies the number of processors in the system.

dwProcessorType

Windows 95: 

Specifies the type of processor in the system.

Windows NT: 

This member is no longer relevant, but is retained for compatibility with Windows 95 and previous versions of Windows NT. Use the wProcessorArchitecture, wProcessorLevel, and wProcessorRevision members to determine the type of processor.

This member is one of the following values:

Value
PROCESSOR_INTEL_386
PROCESSOR_INTEL_486
PROCESSOR_INTEL_PENTIUM
Windows NT only: PROCESSOR_MIPS_R4000
Windows NT only: PROCESSOR_ALPHA_21064

dwAllocationGranularity

Specifies the granularity with which virtual memory is allocated. For example, a VirtualAlloc request to allocate 1 byte will reserve an address space of dwAllocationGranularity bytes. This value was hard coded as 64K in the past, but other hardware architectures may require different values.

wProcessorLevel

Windows 95: This member is not used.

Windows NT: Specifies the system’s architecture-dependent processor level.

If wProcessorArchitecture is PROCESSOR_ARCHITECTURE_INTEL, wProcessorLevel can be one of the following values:

Value	Meaning
3	Intel 80386
4	Intel 80486
5	Pentium

If wProcessorArchitecture is PROCESSOR_ARCHITECTURE_MIPS, wProcessorLevel is of the form 00xx, where xx is an 8-bit implementation number (bits 8-15 of the PRId register). The member can be the following value:

Value	Meaning
0004	MIPS R4000

If wProcessorArchitecture is PROCESSOR_ARCHITECTURE_ALPHA, wProcessorLevel is of the form xxxx, where xxxx is a 16-bit processor version number (the low-order 16 bits of a version number from the firmware). The member can be one of the following values:

Decimal Value	Meaning
21064	Alpha 21064
21066	Alpha 21066
21164	Alpha 21164

If wProcessorArchitecture is PROCESSOR_ARCHITECTURE_PPC, wProcessorLevel is of the form xxxx, where xxxx is a 16-bit processor version number (the high-order 16 bits of the Processor Version Register). The member can be one of the following values:

Decimal Value	Meaning
1	PPC 601
3	PPC 603
4	PPC 604
6	PPC 603+
9	PPC 604+
20	PPC 620

wProcessorRevision

Windows 95: This member is not used.

Windows NT: Specifies an architecture-dependent processor revision. The following table shows how the revision value is assembled for each type of processor architecture.

Processor Architecture	Value
Intel 80386 or 80486	A value of the form xxyz. If xx is equal to 0xFF, y - 0xA is the model number, and z is the stepping identifier. For example, an Intel 80486-D0 system returns 0xFFD0. If xx is not equal to 0xFF, xx + 'A' is the stepping letter and yz is the minor stepping.
Intel Pentium, Cyrix, or NextGen 586	A value of the form xxyy, where xx is the model number and yy is the stepping. For example, a value of 0x0201 indicates Model 2, Stepping 1.
MIPS	A value of the form 00xx, where xx is the 8-bit revision number of the processor (the low-order 8 bits of the PRId register).
ALPHA	A value of the form xxyy, where xxyy is the low-order 16 bits of the processor revision number from the firmware. Display this value as follows: Model ‘A’+xx, Pass yy
PPC	A value of the form xxyy, where xxyy is the low-order 16 bits of the Processor Version Register. Display this value as a fixed point number: xx.yy

Remarks

Beginning with Windows NT 3.51 and the initial release of Windows 95, the SYSTEM_INFO structure has changed as follows:

• The dwOemId member has been changed to a union. The union supports a new way to describe processor architecture used by Windows NT, while maintaining compatibility with Windows 95 and previous versions of Windows NT.

• The dwProcessorType member is now obsolete on Windows NT. It is still used on Windows 95.

• A previously reserved DWORD member at the end of the structure has been replaced by the wProcessorLevel and wProcessorRevision members. Windows 95 does not use these members.

See Also

GetSystemInfo, MapViewOfFile, MapViewOfFileEx 

Questions: