80C187

270640 – 4

Precision Control

00

24 Bits (Single Precision)

01

(Reserved)

10

53 Bits (Double Precision)

11

64 Bits (Extended Precision)

Rounding Control

00

Round to Nearest or Even

01

Round Down (toward b %)

10

Round Up (toward a %)

11

Chop (Truncate toward Zero)

The ‘‘infinity control’’ bit is not meaningful to the 80C187 To maintain compatibility with the 8087 this bit can be

Figure 5 Control Word

15

7

0

CONTROL WORD

a

0

STATUS WORD

a

2

TAG WORD

a

4

a

6

0

a

8

a

A

000000000000

a

C

Figure 6 Instruction and Data Pointer Image in Memory

10