Fundamentals of Computer Systems

Question 1

What is an application software?

Answer 1

A program that completes a specific task for a user (e.g. Web Browser, Word Processor)

Question 2

What is an operating system?

Answer 2

A system that allows the user to control the computer with ease
- It provides a user interface between user and hardware
- Hides complexity of the hardware from the user
- It controls access to the computer’s resources (memory management, processor scheduling)

Question 3

What is a utility program?

Answer 3

Programs designed to maintain the computer
(E.g. Defragmenting hard drives, data backup, data compression)

Question 4

What is a library program?

Answer 4

A collection of resources used to develop a program, which includes pre written code and subroutines
Designed to simplify the process of making a program

Question 5

What is a translator?

Answer 5

Software that converts source code into machine code

Question 6

What is an assembler?

Answer 6

A translator which translates assembly language into machine code

Question 7

What are the properties of assembly language?

Answer 7

1) Translation is quick and straightforward
2) Assemblers are platform specific, meaning different assemblers are needed for a different type of instruction set

Question 8

What is a compiler?

Answer 8

A compiler is used to translate high level languages (C#, Python) into machine code

Question 9

What is an interpreter?

Answer 9

An interpreter is used to translate high level languages to machine code line by line

Question 10

What are the differences between Compilers and Interpeter?

Answer 10

1) A compiler checks for errors before translating and once there are no errors, it translates all at once. An interpreter begins translating and checks for errors as it goes. Meaning a Compiler will not compile if there are any errors
2) Interpreters don’t produce object code, so the interpreter is needed to execute the program, whilst the compiler isn’t needed to execute once it has been compiled
3) Compiled code can only be executed on a machine with the same instruction set, interpreted code is more portable
4) Compilers offer more protection of source code as it isn’t needed once it has been compiled.

Question 11

What is intermediate code?

Answer 11

1)Some Compilers don’t produce machine code straight away - but translate source code into intermediate language - this is because intermediate code can be used on different platforms
2) The intermediate language is then executed using a virtual machine as it isn’t directly executable
3) Each processor instruction set has its own virtual machine which exexcutes the intermediate code, meaning it can be used on many different types of platform whereas compilers can’t

Question 12

When would a compiler be used?

Answer 12

A compiler is often used when sharing code (e.g. selling a computer game)
- It produces object which can be shared, means users can’t access the source code.
- Its more convenient as an interpreter isn’t required.

Question 13

When would an interpreter be used?

Answer 13

• When a program needs to be run by multiple computers, which may contain processors with different instruction sets
• E.g. A Web Browser

Question 14

What is machine code?

Answer 14

A low level language which uses 1s and 0s

Question 15

What is assembly language?

Answer 15

A low level language which uses mnemonics to simplify the process of writing programs

Question 16

What is a high level language?

Answer 16

Languages such as C#, Python which uses English instructions to help program.
They must be compiled into machine code for computers to execute them

Question 17

Pros of High level language compared to low level language

Answer 17

Pros -
1) Portable - Programs aren’t specific to certain processors
2) Easy for humans to understand as they are in English
3) Often extra features (e.g. Data types such as arrays and records)
4) Easier to debug as named variables and in English

Question 18

Cons of High level language

Answer 18

Must be translated into object code to be executed - this can be very time consuming.

Question 19

Pros of Assembly code compared to machine code

Answer 19

1) Easier to debug/find errors
2) Easier to understand - takes less time to code

Question 20

What is the opcode?

Answer 20

The instruction given to the processor for it to execute

Question 21

What is the operand?

Answer 21

The value that is returned when the processor executes the opcode

Question 22

What are the different types of resource management the Operating System Performs?

Answer 22

Processor Management – Which is when the operating system schedules the different tasks that needs to be performed by the processor, ensuring everything can be done efficiently – this can involve allocating cores to different applications
Memory Management – Allocating different amounts of RAM to different processes, for example programs being currently used will be allocated more memory than ones that are in the background
Virtual Memory – When RAM is full, the operating system will take the background processes and place them in virtual memory (a memory location on the hard disk) until they are ready to be used again, saving space within RAM

Question 23

What is a Half Adder?

Answer 23

A logic circuit usded to add two Boolean Values
Contains 2 inputs, 2 outputs and 2 Logic Gates (XOR Gate and an AND Gate)

Question 24

What is a Full Adder?

Answer 24

A half adder is only usable if there are no carry bits - as the carry bit is a third input and we only have 2 inputs - so if there is a carry bit, we use a full adder.
A full adder allows us to add two boolean values that contain a carry bit
Contains 3 inputs and two outputs
2XOR Gates, 2 AND Gates and an OR Gate

Question 25

What is an Edge Triggered D Type Flip Flop?

Answer 25

A logic circuit which can be used as a memory unit for storing the value of a single bit
Has Two Inputs: Data Signal, Clock Signal
The Clock Signal switches between 0 and 1 at a set frequency, the value of the output depends on what state the data signal is in, but only when the clock is on a rising edge