Computer Basics: Memory and I/O Subsystems, Slides of Computer Science

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Memory and I/O subsystem

Basic components of a

computer

• PROCESSOR;

• MEMORY SUBSYSTEM;

• INPUT/OUTPUT (I/O) SUBSYSTEM

Specification of a simple processor System

Memory Subsystem

I/O subsystem

Entity Declaration of I/O subsystem

LIBRARY ieee;

USE ieee.std_logic_1164.all;

USE WORK.comp_pkg.ALL;

ENTITY IO IS

PORT (Addr : IN IOAddrT ; -- I/O address bus

Length : IN STD_LOGIC; -- byte/word control

Rd, Wr : IN STD_LOGIC; -- I/O access control

Enable : IN STD_LOGIC; -- I/O enable control

Rdy : OUT STD_LOGIC; -- I/O completion signal

Data : INOUT WordT ); -- I/O data bus

END IO;

Processor State

Behavior of Processor

INSTRUCTION

SEQUENCING

• SEQUENTIAL UNLESS

– 1. UNCONDITIONAL BRANCH

– 2. CONDITIONAL BRANCH

Instruction Format

Instruction set (cont.)

Instruction set (cont.)