computer systems

Question 1

define hardware

Answer 1

physical components of a computer
e.g
keyboard
monitor
mouse

Question 2

define software

Answer 2

the programs that run on a computer, control the hardware

Question 3

high level language

Answer 3

-any program written in high level is called source code
-need to be translated to machine code
-easy for humans to understand(less complex)
e.g:
python
java
c++

Question 4

low level language

Answer 4

-directly translates to machine code
-difficult to understand
-execute quicker
e.g:
machine code (binary)
assembly language

Question 5

translators

Answer 5

-convert high level language to machine code
3 types:
interpreter
compiler
assembler

Question 6

compilers

Answer 6

-takes source code and translates it to machine code in one go
Advantages:
-compiled programs=run quick, as already translated
-can be supplied as an executable file
-optimise code- runs quicker, takes up less memory space
Disadvantages:
-recompiled every time program is changed
-source code compiled on one platform won’t run on another

Question 7

interpreters

Answer 7

-translates to machine code one instruction at a time
Advantages:
-instructions executed as they’re translated
-errors quickly noticed// when error is found, program stops+ user is notified
Disadvantages:
-runs slowly
-has to be translated each time it’s run
-no executable file, so source code has to be supplied (can be modified easily)
-not optimised code

Question 8

assemblers

Answer 8

-translate assembly language (low level) to machine code
-create 1 machine code for each assembly instruction

Question 9

AND gates

Answer 9

-output only 1 (TRUE) if both inputs are 1 (TRUE)
-look like sideways U

Question 10

OR gates

Answer 10

-output = 1 when one or both inputs are 1
-looks like crescent

Question 11

NOT gates

Answer 11

-only one input
-output =0 when input = 1 and vice versa
-triangle+circle

Question 12

system software

Answer 12

-any software that helps run/manage
e.g:
security software
file management

Question 13

application software

Answer 13

-allows user to perform a task
e.g:
word
browser

Question 14

operating systems

Answer 14

-collection of programs that manage+ control the computer

Question 15

roles of operating systems

Answer 15

-control hardware components
-provide platform for software to run on
-provide user interface
-manage processes
-manage memory
-manage input+output devices
-manage apps
-manage security

Question 16

Fetch Decode Execute Cycle

Answer 16

1. The memory address held in the program counter is copied into the MAR (memory address register)
2. The address in the program counter is then incremented - increased - by one. The program counter now holds the address of the next instruction to be fetched.
3. The processor sends a signal along the address bus to the memory address held in the MAR.
4. The instruction/data held in that memory address is sent along the data bus to the MBR/MDR(memory data register)
5. The instruction/data held in the MBR/MDR is copied into the CIR(current instruction register)
6. The instruction/data held in the CIR is decoded and then executed. Results of processing are stored in the ACC (register used by ALU to store calculation results)
7. The cycle then returns to step one.

Question 17

ALU

Answer 17

-performs arithmetic operators+logical decisions
-gateway between primary memory and secondary storage

Question 18

control unit

Answer 18

-fetches decides + executes instructions
-issues control signals that control ha edward
moves data around system

Question 19

registers

Answer 19

-small amounts of high speed memory in cpu
-used by processor to store small amounts. of data
e.g:
-address of next instruction
-results of calc
-current instruction being decodes

Question 20

RAM (random access memory)

Answer 20

-volatile
-when computer =off, RAM content = lost
-written to and read from

Question 21

cache

Answer 21

-small amount of high speed RAN
-built directly in processor
-temp. holds data
-faster processing as processor doesn’t have to wait for data + instructions to be fetched from RAM

Question 22

bus

Answer 22

-used to send data from diff parts of the computer
3 types:
-address
-data
-control bus

Question 23

clock

Answer 23

-sends out electrical pulses to synchronise hardware components
frequency of pulse=clock speed:
-measured in hertz
-higher frequency=more instructions

Question 24

factors affecting performance

Answer 24

Clock speed:
-higher speed=more FDE cycles performed=more instructions
-overclock-when cpu clock is sped up, can cause long term damage
Cache size:
-bigger cache=less time processed waits
Number of cores:
-each core=can FDE its own instruction

Question 25

main memory

Answer 25

-main storage region of a computer that cpu can directly access
-has RAM and ROM

Question 26

ROM (read only memory)

Answer 26

-non volatile
-can’t be written to

Question 27

secondary storage

Answer 27

-non volatile
-long term storage
-saves memory
-can store programs and data for later use

Question 28

Solid state storage

Answer 28

-SSDs, usb sticks
-made from silicon microchips, data stored by holding an electrical current in a transistor
-can be written to
-non volatile
-external secondary storage
-fast+expensive

Question 29

magnetic

Answer 29

-cheap, high capacity, durable
-damaged if dropped
-hard disks that use magnetic fields to magnetise individual sections of a spinning metal disk
-read+written

Question 30

optical

Answer 30

-uses laser ti scan surface of spinning metal+ plastic disc(divided in tracks w lands and pits)
->sensor scans+checks reflected light
-rom media (pre-written data, like movoes)
-Read (r)media=blank read/write RW=disc can be written to more than once

Question 31

cloud storage

Answer 31

-storing data at a remote location
—> when files are sent to cloud they are sent to a server connected to the internet
-files can be uploaded+downloaded as required

Question 32

Adv+ dis of cloud storage

Answer 32

ADV:
-data accessed from anywhere w internet connection
-businesses running cloud storage manage backups and security
-additional storage can easily be added
DISADV:
-hacker can potentially access data from a wehere w wifi
-failed internet= no access
-relying on others for security

Question 33

embedded systems

Answer 33

-small computer part of a larger system/machine
—controls device and lets user interact w it
-have 1/limited number of tasks

Question 34

embedded systems

Answer 34

-small computer part of a larger system/machine
—controls device and lets user interact w it
-have 1/limited number of tasks