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Xbox CPUID Information
written by Michael Steil, 26 June 2002
The Xbox uses a Pentium III compatible CPU manufactured by Intel. The exact features of any IA-32 CPU can be found out using the assembly instruction CPUID. Here is what the Xbox CPU returns:
CPUID Function 0
Get maximum supported standard level and vendor ID string
| Register(s) | Contents | Comment |
| EAX | 2 | Maximum supported standard level |
| EBX-EDX-ECX | "GenuineIntel" | Intel processor |
CPUID Function 1
Get processor type/family/model/stepping and feature flags
| Register(s) | Contents | Comment |
| EAX | 0x68a | Family 6 (Intel P6/P2/P3) Model 8 (P3 (0.18 痠) with 256 KB on-die L2 cache) Stepping 10 |
| EBX | 0 | |
| ECX | 0 | |
| EDX | 0x383f9ff | Feature Flags (see below) |
31 NO Pending Break Event, STPCLK, FERR#
30 NO IA-64, JMPE Jv, JMPE Ev
29 NO THERM_INTERRUPT, THERM_STATUS, and MISC_ENABLE MSRs, xAPIC thermal LVT entry
28 NO Hyper-Threading Technology, PAUSE
27 NO selfsnoop
26 NO SSE2, MXCSR, CR4.OSXMMEXCPT, #XF
25 YES SSE, MXCSR, CR4.OSXMMEXCPT, #XF
24 YES FXSAVE/FXRSTOR, CR4.OSFXSR
23 YES MMX
22 NO THERM_CONTROL MSR
21 NO Debug Trace and EMON Store MSRs
20 NO reserved
19 NO CLFLUSH
18 NO PSN, PSN_DISABLE MSR
17 YES 4 MB PDE bits 16..13, CR4.PSE
16 YES PAT MSR, PDE/PTE.PAT
15 YES CMOVcc, if FPU=1 then also FCMOVcc/F(U)COMI(P)
14 YES MCG_*/MCn_* MSRs, CR4.MCE, #MC
13 YES PDE/PTE.G, CR4.PGE
12 YES MTRR* MSRs
11 YES SYSENTER/SYSEXIT, SEP_* MSRs
10 NO reserved
9 NO APIC
8 YES CMPXCHG8B
7 YES MCAR/MCTR MSRs, CR4.MCE, #MC
6 YES 64bit PDPTE/PDE/PTEs, CR4.PAE
5 YES MSRs, RDMSR/WRMSR
4 YES TSC, RDTSC, CR4.TSD (doesn't imply MSR=1)
3 YES PDE.PS, PDE/PTE.res, CR4.PSE, #PF(1xxxb)
2 YES CR4.DE, DR7.RW=10b, #UD on MOV from/to DR4/5
1 YES CR4.VME/PVI, EFLAGS.VIP/VIF, TSS32.IRB
0 YES FPUCPUID Function 2
Get processor configuration descriptors
| Register(s) | Contents | Comment |
| EAX | 0x3020101 | |
| EBX | 0 | |
| ECX | 0 | |
| EDX | 0xc040841 |
