uses and applications of Control Unit Hardware and Microprogrammed.pptx

1. •By KHURSHEED AHMAD
Introduction to
Control Units

2. CONTENTS
Overview of Control Units
01
Functions of Control Units
02
Types of Control Units
03
Micro-Programmable Control Units
04
Hardwired vs Micro-Programmed
05
Advantages and Disadvantages
06

3. Overview of Control Units
01

4. Definition and Purpose
Control units are crucial for coordinating instruction execution
and processing within the CPU. They manage operation timing
and signal generation, ensuring efficient interaction among the
CPU's internal components.
Importance in CPU Functionality
Different CPU architectures adopt varied designs for control
units, reflecting differences in instruction sets and processing
capabilities. Manufacturers utilize specific architectures to
optimize performance and adapt to workload requirements.
Variations Across Architectures
The control unit (CU) acts as the brain of the CPU, directing
operations such as data movement and instruction execution
without performing data processing itself. It interprets
instructions and generates control signals to coordinate the
execution units.
Role of the Control Unit

5. Devices Utilizing Control Units
GPUs, designed for rendering graphics
and processing parallel tasks, utilize
specialized control units to manage
extensive data flows and computational
threads efficiently, enhancing graphics
performance and processing speed.
Graphics Processing Units
(GPUs)
CPUs are the primary devices utilizing
control units. The CU fetches, decodes,
and executes instructions, making it
integral to the CPU’s overall
performance and functionality.
Control Processing Units (CPUs)

6. Functions of Control Units
02

7. Coordination of Data Movements
Managing Data Flow
The control unit oversees the
movement of data among
processor sub-units like the
ALU and registers. It ensures
data is available for
processing at the correct
times by issuing appropriate
control signals.
01
Hierarchical Processing
of Operations
Control units structure
operations hierarchically to
optimize the execution flow,
implementing fetch-execute
cycles that prioritize timely
data handling and
availability for subsequent
processing stages.
02

8. Instruction Handling
Upon decoding, control units orchestrate the execution of
instructions, managing execution units to process data and
subsequently directing the storage of results back into
memory or to appropriate registers for future use.
Execution and Result Storage
Control units fetch instructions from memory, decode them
to determine the required operations, and prepare necessary
control signals for execution, enabling a seamless flow of
operation within the CPU.
Fetching and Decoding

9. Types of Control Units
03

10. Hardwired Control Units
Hardwired control units utilize fixed logic circuits for control signal
generation. Their structure dictates operational speed but limits flexibility
due to their static nature—modification requires physical hardware
changes.
Structure and Functionality
Hardwired units boast speed and efficiency due to direct signal
pathways; however, their inflexibility and complexity in modifications can
hinder adaptation to emerging computing needs or technologies.
Advantages and Disadvantages
Commonly found in RISC architecture and embedded systems,
hardwired control units are suitable for applications requiring rapid
execution of a predictable set of instructions without heavy
computational variability.
Example Applications

11. Micro-programmed Control Units
Micro-programmed control units utilize
instruction sets stored in memory,
allowing dynamic generation of control
signals via microcode interpretation,
leading to greater functionality and
adaptivity compared to hardwired
systems.
Structure and Operation
The flexibility of micro-programmed
control units facilitates the support of
complex instruction sets, easier
modifications, and the implementation
of advanced features such as
instruction pipelining and multi-core
processing.
Benefits Over Hardwired
Systems Found in modern processors, micro-
programmed control units are widely
used in general-purpose CPUs,
allowing for efficient management of
complex tasks and compatibility with
sophisticated computing environments.
Real-world Usage

12. Micro-Programmable Control Units
04

13. Single-Level Control Store
Operation and
Interaction
In single-level control stores,
the control signals generated
are directly linked to the
microcode, facilitating
straightforward instruction
processing while engaging
minimal intermediary steps
between instructions.
Addressing Modes and
Microinstruction
Handling
This system employs a
uniform addressing mode,
where each microinstruction
fetches control signals
directly from a control store,
simplifying the link between
high-level operations and
machine-level execution.

14. Two-Level Control Store
Two-level control stores introduce nano-instruction memory,
allowing for even more efficient signal generation by storing
control signals distinctly from microinstructions, reducing
redundancy and optimizing space utilization.
Enhancements and Efficiency
Compared to single-level designs, two-level control stores
provide enhanced performance via quicker signal generation
and improved memory efficiency, balancing complexity with
operational speed.
Comparison with Single-Level Systems

15. Hardwired vs Micro-Programmed
05

16. Implementation Differences
Hardwired systems offer faster execution stats due to direct
logic pathways; however, micro-programmed units can
handle complex instructions more effectively, though at a
slight speed cost due to decode overhead.
Speed and Efficiency Analysis
Hardwired control units rely on fixed logic circuits, while
micro-programmed counterparts use flexible microcode
stored in memory, providing distinct advantages in
configurability and adaptability.
Logic Circuits vs. Microcode

17. Flexibility and Scalability
With their ability to implement intricate
instruction sets, micro-programmed
units support expanded functionalities,
whereas hardwired types often limit
themselves to basic operations requiring
less variability.
Complex Instruction Support
Micro-programmed control units excel in
adaptability; updates and modifications
can be made through software
adjustments, contrasting with hardwired
systems that demand physical changes
to the circuitry.
Modification Ease

18. Advantages and Disadvantages
06

19. Well-Designed Control Unit Benefits
A well-architected control unit enhances instruction execution
rates by optimizing data paths and reducing unnecessary
clock cycles, ultimately boosting the overall performance of
the CPU.
Performance Improvement
Robust design in control units allows for consistent
performance, increased fault detection capabilities, and better
handling of growing workloads, making them well-suited for
scalable applications.
Enhanced Reliability and Scalability

20. Poorly-Designed Control Unit Risks
Performance
Bottlenecks
Inadequately designed
control units can introduce
significant processing delays
and latency, causing
slowdowns in instruction
execution and decreasing the
efficiency of the CPU.
Increased Complexity
and Costs
A poorly conceived control
unit complicates design and
testing processes, which may
lead to increased costs both
in development and
manufacturing, ultimately
affecting the long-term
viability of CPU technologies.

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