4.6 Fundamentals of Computer Systems (Translators)

Question 1

What is the need for translators

Answer 1

-Program code can only be excecuted in machine code meaninng programs in assembly or HLL need to be translated into machine code
before they can be executed by a computer

Question 2

How does an Interpreter work

Answer 2

• Translates and exceucutes each line of code line-by-line.
• For each line a syntax-check is performed and if there are no errors it calls predefined routines to translate lines.

Question 3

What are the advantages of Interpreters

Answer 3

• They can run syntactically correct parts of code evemn when there are errors in other parts of code
• They can be used for debugging and development as they terminate at errors and can be used for testing in a sandbox
• More portable than compilers

Question 4

Drawbacks of using an interpreter

Answer 4

• Program code will need translating every time. This means that the overall time needed
  to execute a program can be very long.
• The process of using it takes up a lot of system resources like RAM as memory space is need for both the source code and the interpreter
• The source code must be distributed to users, whereas with a compiled
  program, only the executable code is needed.

Question 5

How does a compiler work

Answer 5

A compiler converts the whole source code into object code before the program can be executed.

Question 6

Benefits of using a compiler:

Answer 6

• Once the source code has been compiled you no longer need the
  compiler or the source code and you normally don’t need to recompile.
• If you want to pass your object code on to someone else to use it is difficult to reverse engineer to obtain the source code
  -Compiler optimises code in the form of object code , as it does not need to be translated but only executed meaning that it runs faster.

Question 7

Drawbacks of using a compiler:

Answer 7

• Because the whole program has to be recompiled every time you make even the slightest alteration to your
  code, it can take a long time to debug.
• The compiled code will only execute on a computer with the appropriate virtuam machine platform
• The compiler will not produce an executable file if a syntax error is encountered.

Question 8

What does an assembler do

Answer 8

Assemblers translate assembly code programs into executable code.

Question 9

What is Intermediate code (bytecode)

Answer 9

• A semi compiled form of code that is not directly executable
• Containing hardware specific parameters and instructions that will be run by a virtual machine, which is platform independent

Question 10

How is intermediate code used subsequently

Answer 10

• An interpreter is used to convert the hardware specific instructions of the intermediate code into machine code

Question 11

Why do some compilers produce intermediate code as a final output

Answer 11

• Can be executed on any computer using it regardless of the specific processor instruction set.

Question 12

What is the difference between source and object code

Answer 12

Source code is the human-readable code written by a programmer, while object code is the machine-readable output produced after the source code is compiled.

Question 13

Why is it an advantage to use as few gates as possible in a logic circuit

Answer 13

• Minimises the cost of production
• Reduces delay and speeds up processing
• Reduces Power consumption as less system resources will be used.

Question 14

Explain the general purpose of a D Type Flip Flop

Answer 14

synchronous sequential circuit that is used to store state of a single binary data input, and also as a memory unit

Question 15

What is the clock signal of a D Type Flip Flop used for

Answer 15

• To synchronise to operations of a group of flip flips
• Flip Flop stores the state of the input and gives an output at the time of the clock pulse to reflect the current status of the input