Computer Studies Paper 2, WASSCE (SC), 2019

Question 3

 

(a)  Explain the following terms:


  1. storage device;
  2. virtual memory.

(b)Two storage devices have capacities 2 kB and 2 MB respectively.
(i)   Calculate the number of bits that each of 2 kB and 2 MB can hold. 

2 kB: 
2 MB:  Putting the two storage devices together, calculate the total capacity in bytes.

 

 

Observation

 

The expected answers were:


(a)  (i) storage device is a piece of computer equipment/device/hardware/peripheral which can hold /storedata/information. It can also be used to transfer data.

  OR

            Storage device can either be external/internal device used to hold/storedata/information for example magnetic disk, diskette, flash drive, hard drive, DVDand VCD.

OR

Storage device is a digital medium/piece of computer equipment/device/hardware  capable of   storing/holding data/information either temporarily or permanently

    (ii) Virtual memory is the type of memory which allows a programmer to make a

memory device behave as if it has unlimited storage capacity. This supposed “extra” memory is stored on secondary storage.

OR

       Virtual memory is a technique by which additional memory is created on hard disc tocompliment the activity of computer real memory

OR

       It is a temporary storage used by a computer to run programs that need more memory        that it has.

OR

       It is a memory management technique that provides an idealized abstraction of the storage resources that are actually available on a given machine which creates the           illusion to users of a very large memory.

OR

       It is a memory management capability of an operating system that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from random access memory (RAM) to disk storage. 

  (b)  (i) Calculating number of bits held by each device

             2KB

                        1 Kilobyte     = 1024bytes                                                 
                            1 byte            = 8bit                                                       
                             2 kilobytes    =   2x1024x8 
              =  16384bits                                                          
                     2MB
                        1 Megabyte     = 1024 kilobytes                                        
                       1 kilobyte       = 1024bytes                                     
               2 kilobytes      =   2x1024x8                                             
  1 byte            = 8bits                                                       
Therefore:        2MB = 2x1024x1024x8
  = 16777216bits

           (ii)  Calculation of total capacity

                  To add 2Mb and 2Kb together
              2Mb =2x1024x1024bytes = 2097152bytes                            
              2Kb = 2x1024bytes = 2048bytes                                                
              Total in bytes = 2097152 + 2048bytes
   =2,099,200bytes


The question tested candidates’ knowledge of computer storage device and conversion of storage units.

The chief examiner reported that candidates lacked knowledge of conversion from one unit to another.