Microprogrammed and Hardwired Control Unit, Slides of Computer Science

Download Microprogrammed and Hardwired Control Unit and more Slides Computer Science in PDF only on Docsity!

 Introduction

 Types

 Comparison

Control Unit

Presented by – Avinash Koshal

Introduction  CU is the engine that runs the entire computer w the help of the control signals.  It perform the correct sequencing of the correct signals.  It controls everything with a few control signals t points within processor and a few control signals the system bus.

Control Signal Sources  Clock

 It helps to synchronize the operation. It causes one micro-

operation to be performed for each clock pulse

 Instruction Register

 Op-code for current instruction

 Determines which micro-instructions are performed

 Flags

 State of CPU

 Results of previous operations

Control Signal Sources  From Control Bus

 Interrupts / Bus Requests

 Acknowledgements

Types  There are two design approach for CU:

 Hardwired approach

 Micro-programming approach

Micro programmed Approach  All controls that can be activated simultaneously grouped together to form the control words.  These words are stored in the control memory.  The control words are fetched from the control memory and are routed to various functional uni to enable appropriate processing hardware.

Functioning of Micro programmed Control Unit

Control Unit Function

 Sequence login unit issues read command

 Word specified in control address register is read into

control buffer register

 Control buffer register contents generates control sign

and next address information

 Sequence login loads new address into control buffer

register based on next address information from contro

buffer register and ALU flags