How Computers Store Data

TERMS• discrete data• continuous data, • bi-stable device,• number system, • binary number system,• denary number system• human-readable data• machine –readable data• natural numbers• whole numbers, integers• real numbers, magnitude• base, number, digit

QUIZ• Classify each set of data as discrete or continuous.

• 1) The number of suitcases lost by an airline.

• 2) The height of corn plants.

• 3) The number of ears of corn produced.

• 4) The number of green M&M's in a bag.

• 5) The time it takes for a car battery to die.

• 6) The production of tomatoes by weight.

QUIZ ANSWERS• 1) Discrete. The number of suitcases lost must be a whole number.

• 2) Continuous. The height of corn plants can take on infinitely many values (any decimal is possible).

• 3) Discrete. The number of ears of corn must be a whole number.

• 4) Discrete. The number of green M&M's must be a whole number.

• 5) Continuous. The amount of time can take on infinitely many values (any decimal is possible).

• 6) Continuous. The weight of the tomatoes can take on infinitely many values (any decimal is possible).

Why do computers store data?

• For processing– Temporarily• using Random Access Memory (RAM)

• For later use– permanently or semi-permanently• using secondary storage devices and media

Computers do not store data the way we see it, but in the form of binary digits

Why binary digits?

• The computer is an electronic device• The computer is a digital device

• Electronic– the computer uses electricity to work

• Digital– the use of binary digits to store data

The computer’s memory

• The computer’s memory is made up of tiny two-state electronic devices called bi-stable devices.

• A bi-stable device can exist in only one of two possible states i.e. on or off.

• Bi-stable devices respond to the presence or absence of an electric current:– Absence of an electric current - off state– Presence of an electric current - on state

Binary digits and data

• Binary digITS (BITS)• 1 ON• 0 OFF

• This is why data is stored in the form of binary digits (bits)

• Input data is converted to binary digits in order to be processed and stored

Binary digits and data (cont’d)

• Information for the user is converted from binary digits into human-readable form

• Every character on the keyboard can be

represented internally using a combination of 8 bits or 1 byte

• The computer uses various representation schemes to convert data to binary form

• Numeration/number system: any notation for the representation of numbers

• human-readable format is a representation of data or information that can be naturally read by humans

• Machine readable format-

Homework

1. Logon to IT for CSEC– Read and take notes on pages 55 – 56

Homework (cont’d)1) All ___________ that is _________ into a computer system must be

_________ temporarily in ________________. The computer’s

___________ is made up of ___________________ which can exist in only one

of _______ possible __________. As a result, the _________________ one and

zero are used to represent the ________ and __________ states respectively.

___________ data is therefore _____________ to its binary __________________ in order to be

_______________ and ____________. It is then _____________ from ______________ back to

its original form in order to be ___________ to the user.

Fill in the blanks in the above paragraph using the words given in the list below. Remember that a word may be used more than once.Main memory, data, representation, memory, stored, bistable devices, converted, states, output, two, binary digits, input, on, processed, off, binary.