CS 230

1
CS 230

• HP 15C A Stack Calculator

2
High Level Languages

• C
• Java
• Basic
• Cobol
• Fortran
• Pascal
• Algol

3
Machine Languages

• Every CPU has its own machine language
• Commands are numbers
• CPU (Machine) does not understand High-Level
  Languages!

4
Example HP 15C
Architecture of the CPU - control unit (CU),
decodes instructions and initiates their
execution - arithmetic/logic unit (ALU),
performs arithmetic and logic operations -
registers, provides the storage workspace needed
for manipulating data.
5
User Interface - keypad, used for inputting
data and commands - display, used for output
of results
6
Sample Program
5 enter 2 /
Result displayed will be 2.5
7
Reverse Polish Notation

• Operands are entered first, followed by operators
• Uses a stack to keep track of operands and
  intermediate results
• Final result is the value on the top of the stack
  when the operation is completed

8
Sample Program Revisited
In machine language, the previous program would
be
5 (alternatively, 28) 36 2 (alternatively, 38) 10