Outline two resource management techniques that are likely to be carried out by the operating system of a desktop computer.

Outline one way the operating system hides the complexity of the hardware from the computer user.

Contrast the memory requirements of a laptop computer and a file server.

Contrast the processor speed requirements of a laptop computer and a file server.

State two types of sensor that are required to control the lighting to ensure it switches on when it is required.

Explain how the system makes use of the data it receives from the sensors to determine when to switch the lights on.

Outline how the system will prevent the lights from being switched off too quickly when it thinks the room is unoccupied.

Award [4 max]  

Virtual memory;
to enable the hard drive to act as primary memory if required;

Paging;
scheme by which a computer stores and retrieves data from secondary storage for use in main memory;

Multitasking;
to enable more than one application to run at the same time;

Scheduling (method by which work is assigned to resources that complete the work);
to determine which process will own CPU for execution while another process is on hold.;

Policies (ways to choose which activities to perform);
according to which decisions are made about which operations should be authorized/ which resources should be allocated;

Interrupt handling;
so that urgent tasks required by parts of the system may be executed;

Polling;
to sampling the status of an external device;

Mark as 2 and 2.

Award [2 max]  
Award 1 mark for the virtual machine (presented by the OS to the user, hiding all the complexities of the hardware behind layers of OS software) and 1 mark for an expansion.

The virtualization of real devices;
such as the use of drive letters for partitions to represent a virtual hard drive;

Use of icons;
to represent peripherals/to access different drives; 

Award [2 max]  
The primary memory/secondary memory in a laptop will be less / smaller than would be found on a file server;
because it is a smaller device that is used by an individual, so doesn’t need to store / run so many programmes simultaneously;

Award [2 max]  
The processor of a file server would be faster/have more cores than that of a laptop;
as it has many more resources to manage/as it needs to keep track of many workstations/printers/peripherals;

Award [2 max]  
Light sensor;
infra-red/motion sensor;

Award [4 max]  
The sensors send data to the processor continuously;
The data received from the sensors is converted to digital (using an analogue to digital convertor);
The readings are compared to pre-set values in the controller/system;
If the light level is found to be below the pre-set value and a presence is detected (in the room);
A signal is sent to the actuator to turn on the lights;

Award [2 max]  
A timer (set to 5 minutes);
If the light level is found to be below the pre-set value a timer is activated but the lights remain on;
When the timer reaches 5 minutes, the lights switch off (if no further presence is detected);

This question was answered well by many students. Part (a) was reasonably well answered with many gaining at least two of the marking points.

Part (b) was well answered.

Students generally have problems with compare/contrast questions, describing the requirements individually without contrasting, as was the case in Part(c).

Students generally have problems with compare/contrast questions, describing the requirements individually without contrasting, as was the case in Part(c).

A large number of candidates scored full or nearly full marks for the questions (d)

A large number of candidates scored full or nearly full marks for the questions (e)

A large number of candidates scored full or nearly full marks for the questions (f)