Modem Terminology Overview
Modem Terminology Overview - Page
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SPOT 14.4
SPOT 14.4 User's Guide
User's Guide
38GDE00001SCF - Issue 4 (11/96)
38GDE00001SCF - Issue 4 (11/96)
Serial and Parallel Data Handling
Serial and Parallel Data Handling
Your computer can process the information in Bytes in two distinctly
different ways. It can accept the bits in either a Serial or Parallel format.
Serial Data
Serial Data
If today's date were the 25th of July 1995, you would write this as "2"
followed by a "5", followed in turn by a "/", "0", "7", "/", "9" and "5". This is
like serial communication as you dealt with each character one at a time.
But since each character you wrote contains only one part of the date,
the actual date (our byte) can only be interpreted after you have written
all eight parts (bits).
When working in a serial mode your computer works in a similar way.
Data bytes are passed one bit at a time, the computer stores these
temporarily until it has received all 8 bits when it can interpret the
complete byte. It then clears the temporary store to prepare to receive the
bits of the next byte.
Parallel Data
Parallel Data
When you borrow a book from the local library, the librarian stamps the
date on the fly sheet using a date stamp. In this instance, all the parts
(the bits) of the whole date (the byte) are conveyed in a single action.
This is like parallel communication.
Computers work almost exclusively in parallel mode. The components
exchange information along a DATA BUS. This is a group of eight
electrical wires, each carrying one data bit. When data is exchanged via
the data bus, all eight lines are read simultaneously, thus transmitting a
whole byte in a single action.
Although your computer uses parallel data internally, the data transmitted
through the modem has to be serial because the telephone line is a two
wire system. Your computer has a built in facility (known as an RS232,
serial or comms interface) which converts parallel to serial data and vice
versa.