Topic 6 - Fundamentals of Computer Systems

Question 1

What are the two components of computer systems?

Answer 1

The two primary components of a computer are hardware and software.

Question 2

Define one of the components of computer systems.

Answer 2

Hardware is the electrical and electro-mechanical components of a computer such as the keyboard, mouse, speakers, hard drive or SSD, power supply, printer.

Question 3

Define another one of the components of computer systems.

Answer 3

Software is the program and program code of an application of a computer; this may be a word processor, video games, and other programs such as Spotify, Internet Explorer, Skype and many more.

Question 4

Give examples of devices that are part of both components of computer systems.

Answer 4

Wireless routers and wireless keyboards are devices which are both hardware and software.

Question 5

Define application software.

Answer 5

Application software is simply software which completes a specific task for the user.

Question 6

Define system software.

Answer 6

System software is software which maintains the computer, ensuring it is running healthily with no problems.

Question 7

What are the 4 types of system software?

Answer 7

• Utility program
• Operating System (OS)
• Library programs
• Translators

Question 8

Define an OS.

Answer 8

An operating system is the system software which manages the computer’s hardware and peripherals and also completes other important tasks such as providing a user interface for the user.

Question 9

What are utility programs?

Answer 9

Utility programs are programs that maintain and optimize the computer, and its storage via housekeeping tasks; data backup, defragmentation of hard drive, data compression and data encryption.

Question 10

Describe library programs.

Answer 10

Library programs are pre-compiled routines/modules which can be imported into the code of a program by the user. These programs are very useful as they simplify the programming process and prevent unnecessary lines of code.

Question 11

Describe translators.

Answer 11

Translators are another type of utility programs which translate between languages, typically translating the program source code to low-level machine code.

Question 12

State the types of translators.

Answer 12

Types of translators are:

• Compilers
• Assemblers
• Interpreters

Question 13

Why were low-level languages created?

Answer 13

At the time during the earliest computers, these computers were very weak in speed and memory so programmers would write instructions which directly manipulated the CPU to execute commands.

Question 14

What are high-level languages?

Answer 14

High-level programming languages are languages which directly communicate with the processor of a computer, making the programming process much easier.

Question 15

What are low-level languages?

Answer 15

Low-level languages are instructions which directly manipulate the CPU of a computer as they are specific to the type of CPU and directly affect the CPU.

Question 16

What are the two types of low-level languages?

Answer 16

• Machine Code

- Assembly Language

Question 17

Define machine code.

Answer 17

Machine code is a type of low-level language in the form of pure binary bits.

Question 18

Give a disadvantage of machine code.

Answer 18

Because it is in the form of binary bits, machine code can get very long, making it hard to debug.

Question 19

Give another disadvantage of machine code.

Answer 19

Machine code can be prone to errors.

Question 20

Describe an advantage of machine code.

Answer 20

Because it is already in binary format, when being executed by the computer it does not need to be translated so it can run easily and quickly, making it powerful and strong.

Question 21

State two uses of machine code.

Answer 21

Machine code can be used in real-time applications and embedded systems.

Question 22

Define assembly languages.

Answer 22

Assembly languages are another type of low-level language which use mnemonics (ADD, MOV, STR…) instead of binary code, aiming to simplify the programming process.

Question 23

Describe an advantage of assembly languages.

Answer 23

Assembly languages are generally less vulnerable to errors as they are more compact than machine code.

Question 24

What correlation do assembly languages and machine code have?

Answer 24

Assembly languages and machine code have a 1 to 1 correlation;
e.g: The assembly instruction MOV R2, R1 is directly correlated to the binary number 11011001:
MOV stands for the MOVE command, represented by the 4-bit identifier 1101, R2 stands for Register 2, so in binary this would be 10, and R1 stands for Register 1 so in binary this would be 01.

Question 25

Give examples of imperative high-level languages.

Answer 25

High-level languages include FORTRAN, Python, C++, C#, Delphi, Ruby and many more.

Question 26

How are instructions presented in high-level languages?

Answer 26

High-level languages instructions don't include mnemonics or binary code; English instructions such as while, if, print and mathematical symbols like '+', * are used instead.

Question 27

Define imperative high-level languages.

Answer 27

Imperative high-level languages are a type of high-level languages which is similar to low-level languages because the code tells the computer how to execute the code via commands and steps for the computer to perform. This is a sharp contrast from declarative programming where the computer is only told what to execute.

Question 28

How do named variables, commenting and indenting help with coding?

Answer 28

These features make coding so much better and easier to debug as the code is far more detailed.

Question 29

How useful are built in functions to programming?

Answer 29

Built in functions in high level programming are very useful as they help simplify the programming process, saving lots of time.

Question 30

What happens when a high-level language program is run?

Answer 30

When a high-level language program is run, a compiler or interpreter translator will translate the code into machine code for the computer to understand, then the program will be executed.

Question 31

What is an assembler?

Answer 31

An assembler is a type of translator which translates assembly code to machine code. As assembly code and machine code have a 1 to 1 correlation, the procedure should be straightforward and simple. Assemblers are also platform specific as certain assemblers only work on certain processor instruction sets.

Question 32

What is a compiler?

Answer 32

A compiler is a type of translator which is used in many high-level languages to translate the code to machine code. This makes it platform specific as machine code may differ depending on the CPU used.

Question 33

What is an interpreter?

Answer 33

An interpreter is a type of translator which translates high-level language code into machine code. Unlike, compilers, interpreters do not produce object code.

Question 34

How does a compiler work?

Answer 34

A compiler first checks for errors in the program then translates the entire program into machine code. If an error is detected during the initial check, the program won't be translated.

Question 35

How does an interpreter work?

Answer 35

The interpreter has individual procedures for each program instruction, but the general process is that the interpreter will check for errors line by line, and if there are no errors then the line will be translated into machine code; this may mean if errors are detected later in the program, the program will still be partially translated.

Question 36

Give one problem with using an interpreter.

Answer 36

During translation, the source code must be present with the interpreter, posing a huge security risk as the source code is at risk of extraction.

Question 37

What are intermediate languages used for?

Answer 37

Intermediate languages are used by compiler translators to help translate program source code into machine code, so the program can be executed.

Question 38

Describe how compilers use intermediate languages.

Answer 38

The high-level source code is compiled into bytecode, an intermediate language, and as bytecode is a portable file, it can be run on any computer as long as the computer runs JVM (Java Virtual Machine). Here, the Java compiler will convert the bytecode into machine code.

Question 39

Explain how intermediate language is effective for interpreters.

Answer 39

Intermediate language will allow the source code to be present and translated only once, so it can be prevented from extraction, making the interpreter more secure.

Question 40

Define the term 'source code'.

Answer 40

Source code is defined as the input to a translation; for assemblers this is assembly code, for compilers and interpreters this is the high-level language code.

Question 41

Define the term 'object code'.

Answer 41

Object code is the output of a translation.

Question 42

Define a logic gate.

Answer 42

A logic gate is an electronic device which applies logical expressions to boolean inputs to produce a singular output.

Question 43

Give the names of the logic gates.

Answer 43

- AND - OR - NOT - NAND - NOR - XOR

Question 44

Define the AND gate.

Answer 44

The AND gate is a logic gate with 2 inputs on the left, and create 1 output. A 1 will only be outputted if both inputs are 1. The truth table will have 3 columns (2 for input, and 1 for output). Formula is Q = A x B

Question 45

Define the OR gate.

Answer 45

The OR gate is a logic gate with 2 inputs on the left, combining to create 1 output. If at least 1 input is 1, the output will be 1. The truth table will have 3 columns (2 for input and 1 for output). Formula is Q = A + B

Question 46

Define the NOT gate.

Answer 46

The NOT gate is a logic gate with 1 input on the left and 1 on the right. The output will always be opposite to the input. The truth table will have 2 columns (1 for input and 1 for output). Formula is Q = ‾A (Overline should be over A)

Question 47

Define the XOR gate.

Answer 47

``` The XOR (Exclusive OR) gate is a logic gate with 2 inputs on the left used to combine to make 1 output. Only if strictly one of the inputs is 1, the output will be 1 and if both inputs are 0 or 1, then the output will be 0. The truth table will have 3 columns (2 for input and 1 for output). Q = A ⊕ B ```

Question 48

Define the NOR gate.

Answer 48

The NOR gate is a combination of the NOT and OR logic gates, and its outputs will be the exact opposite of the OR gates outputs; if at least one input is 1, the output will be 0. Q = ‾‾‾‾‾‾ A + B

Question 49

Define the NAND gate.

Answer 49

The NAND gate is a combination of the NOT and AND gates, with its outputs being the exact opposite of the AND gates outputs; if strictly one input is 1 or if there are two 0 inputs, the output will be 1. Q = ‾‾‾‾‾‾‾ A x B

Question 50

What is 'A • B'?

Answer 50

The '•' means multiplication so here the two variables are multiplying, so an AND gate is applied here.

Question 51

What is the answer to C • C?

Answer 51

A boolean value AND itself will always return the value itself; e.g C • C = C, A • A = A...

Question 52

What is the answer to F + F?

Answer 52

A boolean value OR itself will always return the boolean value; F + F = F, G + G = G...

Question 53

Give the answer to E + 1.

Answer 53

A boolean value OR 1 will always be 1.

Question 54

What is ‾‾A (double overline)?

Answer 54

Double overline of a boolean value will just be the value itself as the expression would be: NOT(NOT A).

Question 55

Describe De Morgan's Law.

Answer 55

De Morgan's Law is a law devised for simplifying expressions in Boolean algebra; it reads: 'Break the bar and change the sign'.

Question 56

Give the steps used to carry out De Morgan's Law in simplifying expressions.

Answer 56

1) Change the OR symbol to an AND symbol (or vice versa) 2) NOT the terms on both sides of the expression 3) NOT everything in the expression. 4) Remove double negations (remove NOT overlines) 5) Remove all brackets 6) Depends on the question; if there are two terms repeated at the end in a logic gate (AND or OR), then simplify and cancel the terms out.

Question 57

What are distributive rules?

Answer 57

Distributive rules are a set of rules used for simplifying expressions and expanding brackets in boolean algebra.

Question 58

Give a use of an operating system.

Answer 58

An operating system provides a user interface (GUI, command line or menu-driven) to hide the inner complexities of the computer and let the user access the computer with ease.

Question 59

Give another use of an operating system.

Answer 59

The OS plays the role of the 'middle-man' or messenger as the hardware and software of the computer can't directly communicate, so the OS helps with communication here.

Question 60

What is disk defragmentation?

Answer 60

Disk defragmentation is a type of utility program which constantly rearranges files to prevent fragmentation where large clusters of files are scattered across the drive. This program helps improve file access speeds and times.

Question 61

List the types of application software.

Answer 61

- General purpose software - Special purpose software - Bespoke software - Off the shelf software

Question 62

Define one type of application software.

Answer 62

General purpose application software is software which is not limited to only one purpose. Examples include word processors, graphics packages, spreadsheet software.

Question 63

Define another type of application software.

Answer 63

Special purpose application software is software which only has one purpose/use. Examples include presentation software, driving simulator, payroll/accountancy software.

Question 64

Describe a type of application software.

Answer 64

Bespoke software is a type of application software which is tailor-made for a user or an organisation. This means the user or organisation will have lots of control on the functionality of the program. Examples include the software used for certain armed forces, NASA, or certain e-commerce software.

Question 65

Describe another type of application software.

Answer 65

Off the shelf software is application software which may be purchased from retailers. This can be special or general purpose software.

Question 66

What is data backup?

Answer 66

Data backup is a type of utility program which is only used if a computer system malfunctions. The program restores the computer system to a previous state using a system saved as a backup.

Question 67

Describe data compression programs.

Answer 67

Data compression programs are a type of utility software which compress/reduce file size so they can be transmitted across a network easier or stored easier.

Question 68

Define data encryption programs.

Answer 68

Data encryption programs are a type of utility software which encrypts files and folders to prevent unauthorized access by hackers or cyber attackers.

Question 69

What is an API?

Answer 69

An API (Application Programming Interface) is a user interface which hides the complex operations that take place in a computer whenever we issue commands for those operations (e.g. loading or saving files, recording or playing sounds...)

Question 70

Describe how an API works.

Answer 70

The user gives the API its request, then the API will go to the OS and give it the request and the OS will then send its response to the user via the API.

Question 71

State the individual functions which the OS performs for resource management.

Answer 71

- Backing store management - Processor scheduling - Memory management - Peripheral/IO (Input Output) device management

Question 72

Explain how the OS manages memory (memory management).

Answer 72

As the computer is running, the OS allocates a certain amount of memory onto each running program on the RAM to manage the user's multitasking. However, if the RAM is running low then the OS will remove some programs to free up space and put them on the hard drive. (the HDD here acts as extension or virtual memory)

Question 73

Describe processor scheduling.

Answer 73

Processor scheduling works by the OS managing which programs can send data to the CPU and which can't, causing several instructions of multiple operations to queue. This is linked to multi tasking where the CPU executes small parts of multiple operations, making it appear like processes are running simultaneously.

Question 74

What is a scheduler?

Answer 74

A scheduler is a component in the OS which ensures processor time is used efficiently and no problems occur with the processor time. e.g Windows Task Manager.

Question 75

Give examples of scheduling algorithms.

Answer 75

Examples include: - Round Robin = each process uses the processor for a given time - Shortest job next - Priority system (this is where the process with the most importance is given priority and most processor time).

Question 76

Describe and explain backing store management.

Answer 76

This is another part of resource management which is focused on the OS keeping track of where files are stored on the HDD and any external drives, and also where there is any free space which may be used. The OS needs to know all this information just in case the user performs a save operation for a backup.

Question 77

Describe and explain peripheral/IO management.

Answer 77

IO (Input/Output) management is performed by the OS through its communication with the I/O controller, a component of the CPU. Through this communication, the OS performs important tasks such as checking whether an output device is switched on and ready to receive data and managing CPU interrupt signals such as the 'out of paper' interrupt signal from a printer.

Question 78

Define an interrupt signal.

Answer 78

An interrupt signal is a signal sent to the CPU from external hardware or software programs which interrupts the currently running process on a computer. e.g: If you are typing a document and a window randomly pops up, you won't be able to continue typing until you close the pop-up. The pop-up is an example of the interrupt signal.

Question 79

Give the two components of machine code.

Answer 79

The two components of machine code are the opcode and operand.

Question 80

Define one of the components of machine code.

Answer 80

The opcode is the first part of machine code, covering the first few bits. The opcode stands for 'operation code' as it tells the CPU what it will do.

Question 81

Define another of the components of machine code.

Answer 81

The operand is the next part of the machine code, covering the bits after the opcode. It can be in the form of a number value, or memory address which holds the value.

Question 82

What is the instruction set of a computer?

Answer 82

The instruction set is simply the instructions a computer understands and can execute.

Question 83

Give an example of a declarative programming language.

Answer 83

SQL, a database query programming language, is a widely recognized type of declarative language.

Question 84

Why use high-level languages?

Answer 84

High-level languages allow users to code using algorithms, which is useful as users do not need to constantly worry about every single step of their program.

Question 85

What does it mean by a high-level language being 'portable'? (advantage)

Answer 85

A high-level language being portable, simply means that a program written for one type of computer can be used on another type, given that the program is recompiled on the other type of computer.

Question 86

Give a disadvantage of high-level languages.

Answer 86

In some applications like device drivers, manipulating individual bits is quite important yet high-level languages don't have statements for programmers to perform this.

Question 87

Give a disadvantage of using object code.

Answer 87

A disadvantage of using object code is that it is generally slower than assembly code or even machine code.

Question 88

State another disadvantage of object code.

Answer 88

Embedded systems are small computer systems in electronic devices, and by using object code in these systems, the code can occupy the majority of the already limited memory of embedded systems.

Question 89

Give an advantage of NAND gates.

Answer 89

By only using NAND gates to build a circuit, this can significantly decrease production costs.

Question 90

Describe an advantage of NAND gates.

Answer 90

By using as few logic gates as possible, this can significantly speed up processing power.