1. Information Manipulation
CSCI-N 100
Dept. of Computer and Information Science

2. Doing what its told
Computers deterministically perform instructions to process information
Deterministically
Computer determines which instruction to execute next
Required by construction to execute a specific instruction based only on program and data given to it
No alternatives, no options
Will execute one and only one next instruction

3. Computers… Have no imagination or creativity Have no intuition
Are literal (no decorum, irony, subtlety…)
Do no have a sense of humor
Are not vindictive, cruel…
Are not purposeful
Have no free will

4. The Process Information Manipulation Sits in switches called memory
Memory just ‘holds’ information until called
Cannot manipulate information in memory
Manipulation
Information called
Placed in register
Information manipulated
Put back into memory

5. Fetch and Execute Cycle
A sequence of actions
Getting instructions
Figuring out what to do
Gather data needed to do it
Doing it
Saving the results
Repeat (if necessary)…
Happens millions of times, short period of time

6. What’s in the cycle
Elemental commands (sometimes called machine language)
Each computer has limited number
How many not important
Structures that process the information

7. The Structures Structures that process information
Sequence – done in order one step after another
Decision – yes/no, true/false
Iteration – also called looping
Computer will only follow directions given to it in the written program

8. What’s in the cycle (cont’d)
Any change or interference in instructions can change computers ability to complete task and give any type of result
Blue screen of death
Cyclic redundancy
Computer ‘froze’

9. Properties of memory Discrete locations Addresses Value
Organized in order
Addresses
Location in memory with a given number
Starts at zero (0)
Value
Contents of location
Finite capacity
Each location has capacity of 1 byte (8 bits)

10. Make it Stop Early computers had Start/Stop buttons
Newer machines execute an “idle loop”
Instructions continually check if there is anything to do
Mouse click
Keystroke