Microprocessors

Microprocessors

  • Submitted By: jovin
  • Date Submitted: 08/01/2009 3:39 AM
  • Category: Technology
  • Words: 746
  • Page: 3
  • Views: 324

Introduction to microprocessors

Von Neumanna architecture

CPU

ROM

RAM

I /O

Address bus Data bus Control bus /MEMR, /MEMW, /IOR, /IOW

16 8

Address and data
• • • • • 16 - bit address bus – 216=65536≈64k 20 - bit address bus → 1M (220) 24 - bit address bus → 16M (224) 32 - bit address bus → 4G (232) 8/16/32 - bit data bus – 8/16/32 - bit processor

Address map
0000 16k/4M 4000H 16k/4M 64k, 16M 16k/4M C000H C00000H 16k/4M FFFFH FFFFFFH 64k 16M 8000H 800000H 400000H 000000

Von Neumann architecture
• Common program and data memory • Common program and data bus • Sequential instruction and data access

Harvard’s architecture
Program memory addr. P R Data memory addr.

Program memory

CPU

Data memory

Program (instructions) K

N

Data

Harvard’s architecture
• • • • • Independent program and data memories 2 address buses 2 data buses Parallel access for instruction and data Pipeline mechanism

Procesory RISC i CISC
• • • • • • Reduced Instruction Set Computers Complex Instruction Set Computer CISC ↔ Von Neumann’s arch. RISC ↔ Harvard’s arch. Pipeline mechanism Simultaneous execution and fetching the next instruction

Addressing modes
• Way of defining the position of the operand in the memory • The more addressing modes, the better the microprocessor • Same instructions with different addressing modes • Direct and indirect addressing modes

Addressing modes

100H

instruction

ADD 200H

100H

Instruction

ADD 200H I

200H

Indirect addr.

300H

200H

operand

300H

operand

Addressing modes
• Register addressing (for registers only, e.g. CLA, INC) • Indexed addressing (index register) • Indexed with offset (index and offset registers) • Immediate (operand hidden in the instruction body)

Indexed addressing with offset
instruction Index

+
Adres operand

Offset

+/-

Address = Index ± offset

CPU – Central Processor Unit
Address MAR Memory Address Register...

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