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Unità
1
Codifica delle informazioni
42
in English, please
unità
1
Abstract
CODING INFORMATION
Application software:
group of programmes created
to solve specific user problems.
ASCII (American Standard Code for Information
Interchange):
represents a 7 bit code for the
transmission or storage of characters. The eighth bit
can be used as a parity bit or to extend the number of
allowed values from 128 to 256.
Basic software:
the part of software created with the
purpose of resolving not specific processing tasks but
problems common to, or connected to, the execution of
all types of processing, such as, decoding programmes,
file access systems and the like.
Binary:
system of positional numbering with a base
of two with only two possible symbols.
Bit:
abbreviation of Binary-digiT. It represents the
smallest possible quantity of information which can
be processed or transmitted.
Byte:
a group of 8 consecutive bits. In 8 bit machines
it constitutes the elementary storage cell which can
be individually addressed.
Digital:
used in contraposition to analogue to indicate
a discrete state piece of equipment which operates in
steps, not a continuous scale.
Processor:
system which is able to perform automatic
processing.
Floating point:
(exponential) scientific notation of
real numbers.
Output:
outward transfer of data, for example, to a
printer.
Overflow:
situation in which the result of an
operation is greater than the maximum number
which can be represented in the memory cell or in
the register.
Pixel:
dot forming part of an image. It is the smallest
point whose colour and intensity can be controlled.
Raster:
an image seen as a series of points or pixels.
Glossary
Questions
1
The ASCII code is used to represent:
a
videos
c
printable characters
b
integers
d
images
2
List the main image compression standards.
3
How many bits per pixel are used in black and white,
grey-scaled and colour images?
4
What is the minimum number of bits needed to repre-
sent 133 different pieces of information?
a
5
b
6
c
7
d
8
5
With 8 bits 128 different configurations
can be represented.
T
F
6
The binary number 11011010 corresponds
to 218 in decimal notation.
T
F
7
The number 315 in decimal notation
corresponds to 1110001001.
T
F
8
An image composed of 250 by 100 pixels
in 16-bit colour takes up 12,500 bytes.
T
F
9
A 256 colour image which takes up
2,800 bytes is made up of 400 pixels.
T
F
Computational systems receive input of data and
information, process them by means of a programme
and provide the results in the form of data. The
“tangible” parts of a processing system are called
the “hardware” while the programmes are called
“software”.
Information is represented by a sequence of 0s and 1s
because the basic unit of memory (bit) is only able to
represent 0 or 1. Hence the computer uses logic and
binary arithmetic to carry out its operations.
Alphanumeric information is represented by means of
the ASCII code (or Unicode). Numerical information
is represented in different ways depending on whether
it deals with integers or Real numbers. Images, videos
and sounds are also represented by series of bits with
different standards.
Glossario
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