AMD-K6-2E/400AFR AMD [Advanced Micro Devices], AMD-K6-2E/400AFR Datasheet - Page 47

• Manufacturer Part Number: AMD-K6-2E/400AFR
• Manufacturer: AMD [Advanced Micro Devices]

22529B/0—January 2000
Figure 13. FPU Control Word Register
Figure 14. FPU Tag Word Register
Chapter 3
Symbol
Reserved
Y
RC
PC
PM
UM
OM
ZM
DM
IM
00b = Round to the nearest or even number
01b = Round down toward negative infinity
10b = Round up toward positive infinity
11b = Truncate toward zero
Rounding Control Information
Infinity Bit (80287 compatibility) 12
Rounding Control
Precision Control
Precision
Underflow
Overflow
Zero Divide
Denormalized Operation
Invalid Operation
15
Description
Exception Masks
(FPR7)
TAG
The FPU control word register allows a programmer to manage
the FPU processing options. Figure 13 shows the format of the
FPU control word register.
The FPU tag word register contains information about the
registers in the register stack. Figure 14 shows the format of the
FPU tag word register.
14
13
(FPR6)
TAG
12
11
(FPR5)
TAG
Software Environment
10
Bits
11–10
9–8
5
4
3
2
1
0
Tag Values
00 = Valid
01 = Zero
10 = Special
11 = Empty
9
(FPR4)
TAG
15
8 7
00b = 24 bits Single Precision Real
01b = Reserved
10b = 53 bits Double Precision Real
11b = 64 bits Extended Precision Real
14
(FPR3)
TAG
13
Precision Control Information
12
Y
6 5
11
(FPR2)
TAG
R
C
10
4 3
9 8
(FPR1)
C
P
TAG
AMD-K6™-2E Processor Data Sheet
7
2 1
6
(FPR0)
TAG
M
5
P
0
M
U
4
O
M
3
M
2
Z
M
D
1
M
0
I
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