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Q&A-KCSE Computer Studies Paper 1


(i) Give three advantages and disadvantages of using a touch-sensitive interface.

Advantages

  •  A touch screen is very intuitive
  • Easy to use as the user simply touches what they see on the display
  • Save space as no keyboard or mouse is required.
  • Touch monitors can even be mounted on the wall.
  • Touching a visual display of choices requires little thinking and is a form of direct manipulation that is easy to learn.
  • Touch screens are the fastest pointing devices.
  • Touch screens have easier hand-eye coordination than mice or keyboards.
  • No extra workspace is required as with other pointing devices.
  • Touch screens are durable in public access and in high volume usage

Disadvantages

  • Difficult for people with accessibility issues, e.g no feedback, disability
  • Can be easily damaged/scratched
  • Damaged/scratched screen prevent the interface from functioning as it should
  • Dirty screens difficult to read
  • Users must be within arm’s reach of the display
  • It is difficult to select small items
  • User's hand may obscure the screen
  • Screens need to be installed at a lower position and tilted to reduce arm fatigue
  • Some reduction in image brightness may occur
  • They cost more than alternative devices

Explain the Fetch – Execute cycle and provide an example of a Central Processing Unit (CPU) component for each stage of the cycle

The Fetch – Execute cycle is a sequence of actions, performed by the processor as it fetches
a program instruction from its memory, determines what the instruction wants to do and
carries out those actions. The stages of the cycle are provided below.

  • Fetch the instruction – the processor fetches the instruction from a memory address stored in a program counter and transfers the instruction, via a data bus, to an instruction register. At the end of the fetch operation, the counter points to the next instruction that will be read in the next cycle.
  • Decode the instruction – the processor decodes the instruction stored in the instruction register, including getting any operands required to complete the instruction.
  • Execute the instruction – the decoded instruction is executed.
  • Store the result – the result generated by the execute phase is stored in the main memory, and/or sent to an output device. The program counter is updated with feedback from the arithmetic logic unit (ALU), to a different address from which the next instruction will be fetched.

State advantages and disadvantages of Solid State Drives and Hard Disk Drives

Advantages of  of Hard Disk Drive

  • Hard disk drives are cheaper per gigabyte than solid state drives.
  • Hard disks have a longer lifespan than solid state drives

Disadvantages of Hard Disk Drives

  • Consumes more power than SDD
  • They are noisy.
  • They are slower than solid state drives.
  • They are susceptible to wear and tear as they have movable parts.

Advantages of Solid State Drives

  • Are faster than HDDs
  • It is more durable as it does not have moving parts
  • Consumes less power
  • Are not noisy

Disadvantages of SDD

  • It costs more than a conventional hard disk
  • Have fewer write/erase cycles compared to a hard disk drive
  • Lost data cannot not be recovered

Define an end user license agreement (EULA).

  • An end user license agreement (EULA) describes a contract (agreement) between a software developer and a user of that software.
     

List three other types of software license.

  • Network
  • Commercial
  • Enterprise
  • Proprietary

State one ethical responsibility of software users

  • Users need to ensure that their software is licensed

State advantages of solid state storage media

  • Portable
  • Light
  • Faster access speed
  • No moving parts
  • Efficient power consumption
  • Durable
  • Small physical size
  • Large storage capacity

Distinguish between Incremental and Full backup


Incremental:

  • Only the changes need to be backed up
  • The software/OS/settings are unlikely to have changed between backups
  • Small number of files likely to be used/edited between backups
  • Take less time to backup
  • Each backup will take less memory space to store

Full:

  • Backup all the data/files and software
  • It might not take a significant time to back up entire system
  • He might only have a small number of files to be backed up each time
  • Safer as have more past versions to revert to
  • User may have changed settings on computer
  • Faster to restore the backup
  • Needs to do a full before he can do an incremental

Describe the purpose of two registers that are used by Von Neumann architecture.

MAR( memory address register)

  • Stores the address/location where data will be read/written/accessed/fetched
  • stores address/location of data/instruction being processed
  • stores address/location of data/instruction next to be processed

MDR or  memory data register

  • Stores the data/instruction that is fetched/read from memory
  • stores the data that is to be written to memory
  • stores the data/instruction from the address in the MAR
  • stores data/instruction next to be processed

 Program counter

  • Stores the address/location of the next instruction to be run
  • stores the address/location of the current instruction being run

Accumulator

  • Stores the result of manipulation/process/calculation

Explain why it is not always true that a computer which has  a quad-core processor runs twice as fast as a computer with a dual-core processor

 

  • Software may be designed to run on 1 core and not multiple cores
  • depends on the task(s)  i.e some tasks cannot be split across cores
  • Clock speed also affects speed i.e dual core may have a faster clock speed and quad-core may have slower clock speed so one task may be run faster/slower
  • RAM size also affects speed i.e Quad-core may have less RAM  amount of VM being used
  • Cache size also affects speed i.e Quad-core may have less cache

A company is developing a computer for use in schools.
(a) All computers have a CPU, memory and storage.
(i) Identify the type of physical storage that uses electronic circuits.

 

Solid state
 

Describe what is meant by a clock speed of 3.8 GHz.

  • The number of FDE cycles run per given time/second
  • the frequency that the clock ‘ticks’
  • 3.8 billion cycles/instructions per second

(ii) State what ROM and RAM store.

 

ROM stores BIOS / bootstrap / start-up 

RAM stores currently executing programs and data

Explain how virtual memory can compensate for the limited  RAM capacity in a computer.

  • VM is used when RAM is full  i.e part of the secondary storage used as (temporary) RAM/VM
  • Data from RAM is moved to the secondary storage/VM (to make space in RAM)
  • RAM can then be filled with new data
  • When data in VM is needed it is moved back to RAM

(iii) John von Neumann proposed the concept of a stored program.
   State the two items he proposed to store in main memory.

 Data

Instructions