Intel IA-32 - Manual (Page 379)

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 first processor in the Intel Pentium 4 family is as follows: model (0000B), family (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 16 15 0
P
E
1 2 3 4 5 6 17 18 28 29 30
M
P
E
M
1
N
E T
S P
G C
D N
W
W
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 12 11 8 7 4 3 0
EAX
Family (1111B for the Pentium 4 Processor Family)
Model (Beginning with 0000B)
13 14
Processor Type
Model Family
Stepping
ID
15
Model
Extended Extended
Family
16 19 20 23 24
Reserved