Low Level Languages

Question 1

Explain the term low level language.

Answer 1

• Machine oriented language
• Related to the design of the computer
• Includes assembly language/machine code
• May use labels for addresses
• May use mnemonics for operations

Question 2

Explain the term opcode.

Answer 2

The mnemonic part of an instruction indicating what is to be done.

Question 3

Explain the term operand.

Answer 3

• address field (in an instruction)
• it holds data…
• to be used by the operation given in the opcode
• eg in ADD 12, “12” is the operand

Question 4

Describe immediate addressing.

Answer 4

• used in assembly language
• uses data in address field…
• … as a constant

(data to be used is in address field)

Question 5

Describe direct addressing.

Answer 5

• the simplest/most common method of addressing
• uses the (data in) the address field…
• …without modification
• eg In ADD 23, use the number stored in address 23 for the instruction

Question 6

Explain why registers are used rather than RAM.

Answer 6

• faster to access than Random Access Memory
• used for specific purposes…
• …which involve frequent access

Question 7

Describe the use and purpose of the program counter.

Answer 7

• contains address of next (machine code) instruction
  to be executed
• during fetch execute cycle..
• …contents of PC are copied to MAR
• …PC is incremented
• for a jump instruction, address from CIR is put into
  PC

Question 8

Explain how and why the Index Register is used.

Answer 8

• used in indexed addressing
• stores a number used to modify an address…
• … which is given in an instruction
• allows efficient access to a range of memory locations/by incrementing the value in the IR
• eg used to access an array

Question 9

What language uses mnemonics?

Answer 9

assembly language

Question 10

What language uses only binary code?

Answer 10

machine code

Question 11

What language uses relative addresses?

Answer 11

assembly language

Question 12

What language uses local variables?

Answer 12

high level language

Question 13

What languages need translation before the program can be executed?

Answer 13

assembly and high level language

Question 14

What language may be translated into intermediate code?

Answer 14

high level language

Question 15

Describe indirect addressing.

Answer 15

• uses the address field as a vector/pointer…
• …to the address to be used
• used to access library routines
• eg In ADD 23, if address 23 stores 45, address 45 holds
  the number to be used