3.6.2.1 Classification of Programming Languages.

Question 1

Why did we write programs in a low level language?

Answer 1

Because there was limited speed and memory. These languages directly manipulated the processor, required a great deal of effort on the part of the programmer and were prone to errors.

Question 2

Why were high level languages developed?

Answer 2

They were developed to allow for instructions to be communicated to a computers processor, making the job of programming far easier.

Question 3

Outline what is meant by a low level language.

Answer 3

The earliest electronic computers could only be programmed with low-level languages.
Programs written in low-level languages are specific to the type of processor they are
written for and directly affect the computer’s processor.

Question 4

Define what is meant by machine code.

Answer 4

Binary code that a machine can understand an execute.
Used to represent instructions.
Uses only the binary digits 1 and 0 to represent instructions aka binary code that a machine can underst Programs written in machine code are long and extremely difficult to understand. Because of this, machine code programs are prone to errors and difficult to debug.

Question 5

Outline the two types of a lower-level language.

Answer 5

There are two categories of low-level languages, machine code and assembly language.

Question 6

Why are programmers not constrained when using machine code?

Answer 6

Because the machine code directly manipulates a computers processor, it is a very powerful paradigm.

Question 7

Do programmers have to translate machine code before execution?

Answer 7

There is no need to translate before execution, making the paradigm useful for embedded systems and real time applications, where speed of execution is paramount.

Question 8

Give examples of a high-level programming language.

Answer 8

Java.

Python.

Question 9

What is an imperative language?

Answer 9

A programming language that gives a command to do something.

Question 10

Why are imperative languages high-level?

Answer 10

They allow a programmer to think about the program as an algorithm and to not be concerned about how each tiny step is executed in machine code.

Question 11

What must be done to a program before execution?

Answer 11

The program must be translated into machine code.

Question 12

What is 1GL?

Answer 12

An abbreviation for first generation language. Aka a low-level programming language such as machine code or assembly language.

Question 13

What is a 2GL.

Answer 13

An abbreviation for second generation language. Aka a high-level programming language such as java or python.

Question 14

Why was assembly language developed?

Answer 14

They were developed with the intention of simplifying the process of writing computer programs.

Question 15

Define a mnemonic.

Answer 15

A system such as a pattern of letters, ideas, or associations which assists in remembering something.

Question 16

Outline STO.

Answer 16

Mnemonic for storing the contents of the accumulator into the addressed location.

Question 17

Outline LDA.

Answer 17

Mnemonic for loading the contents of the memory address or integer into the accumulator.

Question 18

Define an instruction set.

Answer 18

the set of bit patterns/binary codes for the machine operations that a processor has been designed to perform

Question 19

Define an op-code.

Answer 19

The part of the machine code instruction that denotes the basic machine operation, e.g. ADD.

Question 20

Define and operand.

Answer 20

The part of the machine code instruction that represents a single item of binary data or the address of a single item of binary data.

Question 21

Outline the advantages and disadvantages of machine code.

Answer 21

Not portable.

Code is difficult for humans to understand.

Errors are very difficult to spot and correct.

Machine code is directly executed by processors.

Question 22

Outline the advantages and disadvantages of assembly code.

Answer 22

Programs are processor specific.

Mnemonics help to
make code slightly
easier for humans to
understand.

Debugging is easier
than with machine code
but still far more difficult
than with high-level
languages.

An assembler must be
used before a program
is executed, but each
instruction has a 1-to-1
correlation to a
machine code
instruction so
translation is quick

Question 23

Outline the advantages and disadvantages of a high-level language.

Answer 23

Portable. Programs are
not specific to certain
processors.

Code uses English,
making it easy for
humans to understand.

Named variables,
indentation and
commenting make
debugging fairly easy.

A compiler or interpreter
must be used to
translate source code
into object code before
it can be executed. This
can be time consuming

Question 24

Outline what is meant by a 1-to-1 correlation.

Answer 24

Each assembly language instruction has a 1-to-1 correlation to a machine code instruction.
For example, the assembly language instruction MOV R2, R1 might be the exact
equivalent of the machine code instruction 11011101.