Revision notes OCR Flashcards
For a digital camera, state:
a) two input devices (2 marks)
b) two output devices (2 marks)
c) one storage device. (1 mark)
a) Examples (2 to be given): buttons; light-sensitive, CCD,
CMOS chip; microphone
b) Examples (2 to be given): screen; speaker; flash
c) Example (1 to be given): card reader
Why does a computer have both ROM and RAM? (2 marks)
ROM is needed for the initial settings and boot sequence;
RAM is needed to store data and programs in use.
What is in RAM when the computer is working? (3 marks)
Operating system; programs; data in use by programs
How does the use of virtual memory affect the performance of a computer? (3 marks)
Data is swapped between RAM and the hard disk; hard disk
access is slower than RAM access, which slows access to data;
performance is slower because transferring data is slow.
How would installing extra RAM affect the use of virtual memory and
what effect does this have on the performance of the computer? (2 marks)
More RAM means fewer data transfers to virtual memory and
improved performance.
What is the purpose of the CPU? (1 mark)
The CPU carries out processing on the computer; it fetches
and executes instructions.
What is meant by ‘2.5 MHz quad core’ when describing a processor? (4 marks)
The CPU clock speed is 2.5 MHz (2.5 million instructions
can be processed per second); it has 4 cores (4 independent
processors working together).
State one advantage and one disadvantage of a dual-core processor over a
single-core processor. (2 marks)
Advantage: A dual-core processor can process data
simultaneously, so faster. Disadvantage: A more complicated
operating system is needed; it is harder to write software for
multiple processors.
Identify two input devices and two output devices on a mobile phone. (4 marks)
Input examples (2 to be given): touch screen; microphone;
accelerometer; light sensor; buttons; camera
Output examples (2 to be given): touch screen; speaker; motor
(to make the phone vibrate)
Identify, with reasons, three devices that would help a visually impaired
person to use a computer. (6 marks)
Examples (3 to be given): Braille keyboard – raised dots
to identify symbols; speaker and voice synthesis to read
documents; microphone with voice recognition to issue
commands
Determine the output from each of the following logic circuits:
a) P = 1
b) Q = 1
c) R = 0
d) S = 1
e) T = 0
f) V = 1
Copy and complete the truth table for the circuit in Figure 2.11. (16 marks)
Why does a computer need secondary storage? (2 marks)
Secondary storage is needed to store data and programs when
the power is switched off because RAM is volatile and loses
contents when there is no power.
What is the most suitable type of secondary storage for:
a) transferring work between home and school (1 mark)
b) distributing a software application (1 mark)
c) storing work and programs on a large school network (1 mark)
d) storing images in a digital camera? (1 mark)
a) USB flash memory drive
b) CD ROM
c) Hard disk drive
d) Flash memory card.
State two reasons why an operating system is necessary in a computer. (2 marks)
An operating system hides the complexities of the hardware
and allows the user to operate the computer without having
to write programs.
Explain the relationship between an application and an operating system. (2 marks)
An application performs a useful real-world job; an operating
system controls the hardware.
List three maintenance actions that can be achieved with a typical
operating system GUI. (1 mark)
Examples (3 to be given): copying files; selecting software;
controlling sound volume; connecting to WiFi; deleting
files; moving files; checking battery state; updating software;
installing new software
Explain why voice input is still an underdeveloped area for user interface
development. (3 marks)
Any 2 of: problems with accents, speed of talking, dialects
Define the term ‘user interface’. (2 marks)
The user interface is the boundary between the computer
and users.
Explain why computer technicians often use the command line in order
to carry out system maintenance. (3 marks)
Examples: greater control; able to group commands; quicker
to operate than a GUI
Explain the advantages of using a GUI to interact with a phone. (3 marks)
Examples: difficult to type on small on-screen keyboard;
no need to learn commands; suitable for non-specialist; can make use of touch screen technology; extra touch facilities available, such as pinch or tap
Explain the term “Interrupt”
a signal/request generated by a device/program
causes a break in execution of a program/stops the program
e.g printer out paper, pressing break key
Explain the term ‘byte’
fixed number of bits/8 bits
represents a character
unit of memory/storage
e/g 11010001
Explain the term CD-ROM
(secondary/portable) storage medium
can be read only (memory)
cannot change data
e.g. used to store programs/data/picutres/films, etc
Explain the term ‘buffer’
- temporary store/memory
- allows speed of CPU/devices to be matched
- to hold data being transferred between peripherals and CPU
e.g pages stored waiting to be printed
Differences between high level and low level languages
high level
- portable
- problem-oriented
- close to English
- one-to-many relationship
- easier to debug/change/update
- needs compiler/interpreter
low level
- machine-oriented
- can be difficult to read
- one-to-one relationship
- needs assembler
