Vol. 3A 9-5
PROCESSOR MANAGEMENT AND INITIALIZATION
9.1.3 Model and Stepping Information

Following a hardware reset, the EDX register contains component identification and revision

information (see Figure 9-2). For example, the model, family, and processor type returned for

the firs t process o r in the I n tel Pent i um 4 fami l y is as fo l lows: mo d el (0000 B ), famil y (1111B),

and processor type (00B).

The stepping ID field contains a unique identifier for the processor’s stepping ID or revision

level. The extended family and extended model fields were added to the IA-32 architecture in

the Pentium 4 processors.

Figure 9-1. Contents of CR0 Register after Reset

Figure 9-2. Version Information in the EDX Register after Reset

External x87 FPU error reporting: 0
(Not used): 1
No task switch: 0
x87 FPU instructions not trapped: 0
WAIT/FWAIT instructions not trapped: 0
Real-address mode: 0
31 19 1615 0
P
E
123456
1718
282930
M
P
E
M
1
N
ET
S
P
GC
DN
WW
P
A
M
Paging disabled: 0
Alignment check disabled: 0
Caching disabled: 1
Not write-through disabled: 1
Write-protect disabled: 0
Reserved Reserved
31 1211 8 7 4 3 0
EAX
Family (1111B for the Pentium 4 Processor Family)
Model (Beginning with 0000B)
1314
Processor Type
Model
Family Stepping
ID
15
Model
Extended
Extended
Family
1619202324
Reserved