receive data, and one for a ground. The data is sent or
received in the form of bits, one alter another in a series,
as shown in figure 3-2. This type of transmission is
desirable whenever a computer system is linked to
outside peripherals over a long distance, such as remote
simultaneously. Parallel transmission requires nine or
ten wires to connect the computer to the peripheral
device (fig. 3-2). Seven or eight lines are required for
data bits, one or two lines for "handshake" purposes,
communicate information back and forth between the
peripheral devices and the computer. This information
transmission is useful for fast data transfer. The
principal drawback is the computer must not be located
relatively close to the peripheral device.
devices, one at each end. These devices are called
MOdulator-DEModulator. A modem converts the
signal for transmission over communication lines (I/O
reconverts the audio signal back to a digital signal
before sending it to the CPU. If this conversion (digital
to audio) was not carried out, the digital signal would
degenerate during transmission and become garbled.
Modems are commonly used to send and receive data
over telephone lines, making them a very valuable tool
perform simple addition. It is the software that makes
everything happen. "Software" may be defined as all
the stored programs and routines (operating aids)
required to use the capabilities of a computer system
systems software and applications software.
and support programs designed to coordinate the
capabilities of the computer itself. These include
programs, such as operating systems, assemblers and
compilers, and utilities.
and operations. These programs control the execution
of other programs. They schedule, assign resources,
monitor, and control the work of the computer. These
actions are carried out without human intervention.
and specific languages. They translate computer
programs written in programming language into
machine language. A language translator for an
assembly language is called an assembler program.
Most high-level language translators are compiler
machine-usable code after it is entered into the
Advanced Photography Course