OCR J277 Mark Scheme - OS Functions

OCR	GCSE (9-1) Computer Science Mark Scheme J277/01: Unit 1.5.1 Operating Systems

Question	Answer	Marks	Guidance
1a	Uses WIMP: GUI Type specific commands: CLI Uses less RAM: CLI Used by technicians: CLI	4	Award 1 mark per correct row. If both boxes ticked, award 0.
1b	Intuitive: Visual icons/menus make it easier for beginners who do not know commands. (1) Touch Optimised: GUI allows interaction via finger taps (WIMP), which is required for a tablet without a physical keyboard. (1)	2
2a	To allocate/find free space in the RAM for the application. (1) To ensure the application does not overwrite the data of other open programs (memory protection). (1)	2
2bi	Secondary Storage / Hard Disk Drive / SSD.	1
2bii	Access Speed: The read/write speed of secondary storage is much slower than RAM. (1) Thrashing: Data takes longer to move to the processor, causing lag/slow performance. (1)	2	Award 1 mark for "slower speed" and 1 mark for the impact/consequence.
3a	The OS keeps each program in a separate, protected part of the memory. (1) It tracks where each program's data begins and ends to prevent overwriting/corruption. (1)	2
3b	The OS allocates a small time slice (or processor time) to each process. (1) The processor switches between the processes extremely quickly. (1) This happens so fast that it appears to the user that they are running simultaneously. (1)	3	Must mention "appears" or "illusion" for full marks on single-core context.
4a	Translation: The computer lacks the specific driver software needed to translate OS instructions into signals the printer understands. (1) Communication: Without the driver, the OS cannot communicate with or control the peripheral. (1)	2
4b	Graphics Card / Webcam / Mouse / Keyboard / Scanner / Microphone.	2	Any two valid peripherals.
5	User Interface Platform Memory Multitasking Time Slice Drivers Peripherals Security	8	1 mark per correct word in correct place. Note: If "Time Slice" is used, allow it. If "Processor" was valid in a different context, here "Time Slice" is the specific mechanism.