AMD-K6 Datasheet, PDF (49/346 Pages) Advanced Micro Devices – AMD-K6 Processor

20695H/0—March 1998
Preliminary Information
AMD-K6^® Processor Data Sheet
EFLAGS Register
The EFLAGS register provides for three different types of
flags — system, control, and status. The system flags provide
operating system controls, the control flag provides directional
information for string operations, and the status flags provide
information resulting from logical and arithmetic operations.
Figure 18 shows the format of this register.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
VV
I
I _{I I} AVR
N O OD I T S Z
A
P
C
DP _F CMF
T P FFFFFF
F
F
F
L
Symbol
ID
VIP
VIF
AC
VM
RF
NT
IOPL
OF
DF
IF
TF
SF
ZF
AF
PF
CF
Reserved
Description
Bits
ID Flag
21
Virtual Interrupt Pending 20
Virtual Interrupt Flag
19
Alignment Check
18
Virtual-8086 Mode
17
Resume Flag
16
Nested Task
14
I/O Privilege Level
13–12
Overflow Flag
11
Direction Flag
10
Interrupt Flag
9
Trap Flag
8
Sign Flag
7
Zero Flag
6
Auxiliary Flag
4
Parity Flag
2
Carry Flag
0
Figure 18. EFLAGS Registers
Chapter 3
Software Environment
31