Glossary 9
chassis
The metal frame to which the electronic components of the
computer (such as the system board, power supply, and drive
bays) are attached The chassis goes inside the part you see,
which is variously called the lid, enclosure, or system unit
cover.
checksum
A number, calculated from a block of data, used to verify the
integrity of that data. For example, a modem could send a
block of data and include the number of 1’s that occur in the
block. The receiving modem could count the number of 1’s it
receives and compare its own number with the transmitted
number. If the numbers are the same, the transmission was
probably OK.
clock
Electronic timer (oscillator) used to synchronize computer
operations. The oscillator generates the timing pulses that
coordinate and enable the flow of data within a digital device.
Also a circuit powered by battery that keeps track of the date
and time for human and various system requirements.
clock speed
The frequency at which a clock oscillates. In microcomputers,
measured in MHz. The faster the clock, the faster the computer
can compute.
CMOS
Complementary Metal Oxide Semiconductor. A chip on the
system board that contains nonvolatile memory. CMOS is
backed up by an internal lithium battery that preserves
clock/calendar data and system configuration parameters stored
in CMOS.
