Asynchronous Transmission

Error Error

Check Stop Check Stop

Bit Bit Bit Bit

0	0 1 0 0 0 1 1 1	0	1	0	0 1 0 0 1 0 1 0	1	1

Start ASCII Start ASCII

Bit Character Bit Character

“G” “J”

Synchronous Data Transmission

Stop Bytes

ASCII Characters (trailer flag)

Sync Char	Sync Char	0 1 0 0 0 1 1 1	0 1 0 0 1 0 1 0			Sync char	Sync char

Start Bytes Error Check

(header flag) Bits

Block

Exercises:

1. Give Russian equivalents of the following phrases:

Patterns of bits coded to represent data; each string of bits; one or two stop bits; error check bit; both sending and the receiving computers; within a communications software program; at the beginnings and the ends of blocks.

2. Say if the following sentences are true or false.

1. When signals are transmitted through modems from one computer to another, patterns of bits coded to represent data aren’t sent one bit at a time. 2. The error check bit is set according to a parity scheme that can be odd or even. 3. The scheme chosen isn’t set within a communications software program. 4. Because asynchronous communication is expensive, it isn’t widely used. 5. Large computers to transmit huge volumes of data at high speeds don’t use synchronous transmission.

3. Insert missing words, use the text’s vocabulary:

1. The … check bit is set according to a parity scheme that can be odd or even. 2. Users of both sending and the receiving computers must agree on the … . 3. It doesn’t matter which … is chosen as long as both computers are using the same one- odd or even. 4. Expensive and complex … devices must be used to keep the transmission activities synchronized. 5. Most … are not equipped to handle synchronous data transmission.