ST486DX ST Microelectronics, ST486DX Datasheet - Page 15

• Manufacturer Part Number: ST486DX
• Description: PROGRAMMING MANUAL
• Manufacturer: ST Microelectronics

save other registers and access data in SMM memory. To use any other register the SMM program-
mer must first save the contents using the SVDC instruction for segment registers or MOV opera-
tions for general purpose registers (See SGS Thomson SMM instruction description Section 2.3).
It is possible to save all the CPU registers as needed. See Section 3.3 for an example saving and re-
storing the entire CPU state.
Address Space
Figure 3 - 1.
Top of SMM
31
31
31
SMM Memory Space Header
I/O Write Data Size
Reserved
CS Descriptor (Bits 63-32)
ST486DX - SMM SOFTWARE CONSIDERATIONS
CS Descriptor (Bits 31-0)
I/O Write Data
Reserved
ESI or EDI
EFLAGS
Current IP
Next IP
16 15
16 15
DR7
CR0
I/O Write Address
CS Selector
3
S
2 1 0
P
I
0
0
-4h
-8h
-Ch
-10h
-14h
-18h
-1Ch
-20h
-24h
-28h
-2Ch
-30h
1713503
25