A

S-REGISTERS

Understanding

A bit-mapped S-Register uses one number to describe a collection of

Bit-Mapped

settings. Bit-mapping allows us to pack a lot of information in a small

S-Registers

space.

 

 

 

 

Bit-mapped registers are in the form of Sr.b=n, where r is the bit-mapped

 

register;.b is the bit; n is 0 (off) or 1 (on).

 

The modem displays the value of an S-Register, as a decimal value

 

between 0 and 255. The modem, however, understands the decimal

 

value as a collection of binary digits (bits).

 

 

How bits are

Bits can be mapped into decimal values. Each bit can be either on (1) or

mapped to decimal

off (0). Eight bits create 256 unique combinations of 1s and 0s. Each of

values

the eight bits can be assigned a number corresponding to its position:

 

b b b b b b b b

 

 

7 6 5 4 3 2 1 0

 

 

Also, each bit can be assigned a value corresponding to its number:

 

Bit

 

 

Value

 

7

27

=

128

 

6

26

=

64

 

5

25

=

32

 

4

24

=

16

 

3

23

=

8

 

2

22

=

4

 

1

21

=

2

 

0

20

=

1

Page 137
Image 137
3Com 56K manual Registers, How bits are, Mapped to decimal, Values