Mano State Machine

Mano State Machine

Links on this page:

Dr. M. Moris Mano describes a basic computer in his textbook,
Computer System Architecture, 3rd edition, 1993.

This computer is a toy computer, but serves to present many of the basic concepts
behind all digital computers and
gives us a good platform to study some key features of assembly language programming.

The sample programs I have included in this tutorial
can be assembled and executed using My Computer Simulator.


Other Links:

Hardware Elements:

Registers:
  • AR � 12 bits, address
    • controls: clear, count, load
  • PC � 12 bits, program counter
    • controls: clear, count, load
  • AC � 16 bits, accumulator
    • controls: clear, count, load
  • DR � 16 bits, data register
    • controls: clear, count, load
  • IR � 16 bits, instruction register
    • control: load only
  • TR � 16 bits, temporary
    • controls: clear, count, load
  • OUTR � 8 bits, output
    • control: load only
  • INPR � 8 bits, input
    • no control lines
  • SC � 4 bits, sequence counter
    • controls: clear, count
Memory:
  • 4096 words x 16bits/word
    • controls: read, writex

Flip-flops (1 bit each):
  • I � indirect addressing mode
  • S � start/stop
  • E � ALU carry out
  • R � interrupt event
  • IEN � interrupt enabled
  • FGI � input available
  • FGO � output processed

Decoders:
  • 3x8 operation (op) code
  • 4x16 sequencer (timing)
Bus:
  • 16 bits
  • 3 bit selector

ALU - operations
  • AC ← AC ∧ DR
  • AC ← AC + DR
  • AC ← DR
  • AC ← INPR (bits 0-7)
  • AC ← AC�
  • shift right, AC(15) ← E
  • shift left,  AC(0 ) ← E


State Machine Flow Chart:



Data Paths



By: Nicholas Duchon
Updated: Nov 14, 2018