1. The Little Man Computer

2. Instruction cycle (fetch)
Read address from Location Counter;
Walk to address Read content

3. Instruction cycle (execute LOAD 1/2)
1. Go to mailbox specified by instruction 2. Read content

4. Instruction cycle (execute LOAD 2/2)
3. Go to calculator and punch content 4. Increment LC

5. Input/output interface
System Block Diagram
CPU
Highest
Address
Memory
Lowest
ALU
Input/output interface
Control unit
Program counter

6. The Little Man Computer

7. Generic CPU With Registers
Program Counter ( PC )
Instruction Register ( IR )
Memory
Memory Address Register ( MAR )
Memory Data Register ( MDR )
Accumulator ( A or Acc )

8. Memory address register
Memory Unit
n bits
Memory cell
bit 0 1 2 3 4
2n-1
bit 1
Memory address register
Address decoder
bit n - 1
m - 1
Memory data register
m bits
p. 160

9. MAR-MDR example

10. A visual analogy for memory