Assembly Language

1
Assembly Language

• Friday, Week 5
• Monday, Week 6

2
Assembly Language

• Set of mnemonic names for the instructions in a
  particular computer's machine language.
• Works on accumulator and memory locations in the
  computer.
• Translated into binary instructions.

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Pippin
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Pippin

• Pippin has an accumulator - a place to store
  intermediate values during computation.
• Similar to the calculator but we have memory
  locations to store values and to load values.

5
Sample Program

• LOD 2
• STO 129
• ADD 129
• STO 129
• ADD 3
• STO 130
• HLT

6
Exercise

• What would be the assembly instructions to add 1
  to the contents of memory location 130?

• STO X Store acc value in mem loc X
• LOD X Load contents of mem loc X into acc
• LOD X Load value X into acc
• HLT Halt execution
• ADD X Add contents of mem loc X to acc
• ADD X Add value X to acc

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Exercise Solution

• LOD 1
• ADD 130
• STO 130
• HLT

8
Exercise

• What would be the assembly language instructions
  to add the values in memory locations 129 and
  132, putting the answer in 128?

• STO X Store acc value in mem loc X
• LOD X Load contents of mem loc X into acc
• LOD X Load value X into acc
• HLT Halt execution
• ADD X Add contents of mem loc X to acc
• ADD X Add value X to acc

9
Exercise Solution

• LOD 129
• ADD 132
• STO 128
• HLT

10
Machine Language

• Assembly language still cannot be read directly
  by the computer - its not in binary.
• Assembly language commands need to be translated
  into binary commands called machine language.

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Pippin Machine Language
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Example Program
13
Exercise
14
Exercise Solution
15
Exercise
16
Exercise Solution
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PIPPIN Lab

• This weeks lab will be to use a simulator called
  PIPPIN to write assembly language programs and
  change them to machine language.
• Lets take a look at PIPPIN.
• Do Pre-Lab Assignment

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JMP

• All commands seen so far in PIPPIN are
  sequential.
• We have no way to make a decision or to skip some
  statements.
• JMP X command says always jump to the command
  labeled X.
• JMZ X checks the accumulator first - if its 0
  then we jump otherwise dont jump.

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Example
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In JavaScript

• The same program in JavaScript would be the
  following
• var z0
• for (var x3 x!0 x--)
• z y
• y z
• Or the following
• y y3