112 Glossary

Flow control: Flow control ensures smooth data communication. If operating speed differs between the personal computer and modem or between your modem and a remote modem and if the remote station runs short of buffer capacity, a transmission halt request is sent from the receiver to the transmitter. When the receiver has enough buffer capacity to resume receiving data, a transmission restart request is sent. There are two ways of flow control, XON and OFF control codes and CTS and RTS signals.

frequency: The number of times a signal repeats an identical cycle within a certain time period.

full duplex: A type of data transmission in which data flows between two devices in both directions simultaneously. See also half duplex.

G

gigabyte (GB): A unit of data storage equal to 1,073,741,824 bytes

 

 

(1024 x 1024 x 1024 bytes). See also byte.

 

Guard time: An interval before and after an escape sequence that

 

prevents the modem from interpreting the escape sequence as

 

data.

H

half duplex: A type of data transmission in which data flows

between two devices in one direction at a time. See also full

 

 

duplex.

 

handshake: After a telephone line is connected from one station to

 

another, some signals are exchanged according to the ITU-T or

 

Bell standard to confirm that the standard is the same between the

 

calling and called stations prior to starting data communication

 

between them. This exchange of signals is called handshake.

 

hangup: Hangup means disconnecting a telephone line to terminate

 

communication

I

input: Information received by a computer from a storage device

such as a disk, or an input device such as the keyboard.