Distinguish between random access memory (RAM) and read only memory (ROM).

Outline the function of an operating system in managing primary memory.

Explain the roles of the data bus and the address bus in the machine instruction cycle.

State how the data stored in the byte will be represented in hexadecimal.

State how many integers could be represented in this byte.

Outline why this byte could not be used to represent characters such as those used in Chinese.

Construct a truth table with two input variables. If the input variables are equal the value of the output variable should be True, otherwise it should be False.

Award [3 max].

RAM acts as temporary storage of data, instructions and programs currently running (for the operating system and for the running applications) whilst ROM is permanent memory (stores the instructions and data that won't change/stores the instructions that the computer needs in order to boot up;
Memory access, both read and write operations are performed on RAM whilst ROM works with read only operation;
If power failures happened during access to RAM then all data will be permanently lost/RAM is volatile memory/whilst if power failure happened during the ROM access no data will be lost/ROM is non-volatile memory;

Award [1] for the answer saying that the function of OS in primary memory management is allocation of specific memory blocks to individual programs and [1] for reallocation up to [2 max].

A part of the OS (memory manager) assigns that block of memory to the program when a running program requests a block of memory;
When the program no longer needs the data in previously allocated memory blocks, they become available for reassignment;

OS ensures the availability of adequate memory for data structures/objects of each running program at all times;
By allocating the memory portions to programs after freeing the space (of the computer memory);

OS (memory management unit) uses virtual memory which provides secondary memory (external storage) for program that does not have enough space in RAM for execution;
After execution of the program this memory is reallocated (used by other programs)/freed;

Note to examiners: Award only [1] an answer such as “OS maintains file allocation table”.

Award [4 max].

Bus is defined as a system that transfers data between hardware components/data bus and address bus enable a processor to communicate with the primary memory;
When the computer processor needs to fetch an instruction from the memory it uses the address bus to specify the (physical) address (of the memory block it needs to access);
It will get the data from (the specific) memory (block) (after checking the address bus to get the read address);
And then it will place this data on to the data bus/data bus carries the data;
When the processor wants to store results of execution to the memory it will set the write address on the address bus;
And put the data/results/to be written to memory on to the data bus (to carry this data);

Award [1 max].
5E;

Award [1 max].

2⁸/256;

Award [1] for identifying why this byte could not be used to represent characters such as those in Chinese and [1] for an expansion up to [2 max].

The characters must be represented as numbers so that computer can deal with them;
One byte (gives us the ability to represent only 256 characters) is enough to hold every possible character in a language which uses a limited set of text symbols, punctuation marks and special characters (for example, English, Spanish, etc.);
Chinese exceeds the 256 character limit and therefore requires more bytes to represent all of the characters in this language;

Award [2 max].

Award [1] for all four input combinations (A,B).
Award [1] for all four correct output values (C).
Note: 1 == True, 0 == False.