Understanding Computer Processors: A Comprehensive Overview

The session begins with a discussion on computer processors, the essential components driving computation. The presenter, Moshirinyaga, introduces the topic and sets the stage for understanding the role of processors in various devices.

A computer processor is defined as a digital device capable of performing computations involving multiple steps. It can be used to set selectable parameters or programmable logics, playing a crucial role in executing tasks efficiently.

Processors are utilized in various roles, including core processors, microcontrollers, embedded processors, and general-purpose processors. Each type serves specific functions in different devices and systems.

Core processors operate in conjunction with another processor and consist of special-purpose processors that perform tasks at high speeds. An example is the 14-point accelerator used to speed up arithmetic operations, enhancing overall computational efficiency.

Microcontrollers are programmable devices dedicated to controlling physical systems like modern automobile engines or automatic doors. They perform functions that do not require extensive computation, focusing on sensor testing and signal transmission for device control.

Embedded processors run sophisticated electronic devices such as wireless routers or smartphones. These processors are more powerful than microcontrollers and often run specialized protocols for communication, although they may not contain all functionalities of a general-purpose CPU.

General-purpose processors are commonly used in day-to-day computer operations. They have evolved from early processors created from discrete logic to modern processors implemented as single VLSI chips, significantly enhancing computational capabilities and efficiency.

There are two major approaches in computer architecture: the Harvard architecture and the Von Newman architecture. The Harvard architecture involves processors connected to two independent memory banks via separate buses to access instructions and data simultaneously. It was developed to overcome the bottleneck of the Von Newman architecture. On the other hand, the Von Newman architecture uses a single memory to hold both programs and data, based on the stored program concept introduced in the 1930s.

The Harvard architecture optimizes one memory unit for programs and another for data, offering advantages in separate memory optimization. However, it lacks flexibility in memory size choices. In contrast, the Von Newman architecture allows complete flexibility in memory allocation for programs and data, offering the ability to load programs into memory like other data items.

Processors vary in functionality and flexibility, with different types such as fixed logic processors, selectable logic processors, and parameterized logic processors. Fixed logic processors are the least flexible, performing a single task without the ability to alter functionality. Selectable logic processors offer slightly more flexibility, enabling multiple functions in a specified way. Parameterized logic processors provide additional flexibility by accepting parameters that control computation.

The Programmable Logic Processor is highlighted as the most flexible in functionality, allowing for the alteration of step sequences with each invocation. It can be programmed to run different programs stored in memory, featuring components like the arithmetic logic unit, controller, local storage, external interfaces, and connections.

The processor's components include the controller, which is the heart of the processor responsible for program execution, and the arithmetic logic unit, serving as the main computation engine performing arithmetic operations. Additionally, local data storage is crucial for holding data values like operands and operation results.

The internal connection within a processor facilitates data transfer between hardware units, such as moving data between local storage and the arithmetic logic unit. The external interface manages communication between the processor and the computer system, handling interactions with external memory and input/output devices.

The role of processors encompasses the core processor and microcontroller, with the core processor specializing in single-task performance at high speeds. On the other hand, the microcontroller is a programmable device dedicated to controlling physical systems, embedded in sophisticated electronic devices like wireless routers or smartphones.

General purpose processors like the CPU are commonly used in PCs. They play a vital role in executing programs and are fundamental components of computer architecture.

The fetch execute cycle is a key element in programmable processors. It involves accessing and executing program instructions in a sequential manner, following a set of fundamental steps.

Programmers use high-level languages to create computer programs, which are then translated into a format that processors can understand. This translation process involves tools like GCC, preprocessor, compiler, and assembler to convert source code into assembly language and eventually into binary code.

The linking process involves creating relocatable object programs by replacing external function references with actual code. This process, along with assembling, converts the source program into binary code, making it executable by the processor.

The clock rate controls the speed at which a processor executes instructions. Higher clock rates are often associated with better performance, but the actual execution time of instructions varies based on the operation being performed, the processor technology, and the program being executed.

Processors vary in speed depending on their use case. For example, an electric door may have a slower response time, while high-speed computers require fast processors to maximize performance. Sales personnel often push for faster clock speeds, claiming it leads to higher performance. However, the clock rate does not solely determine processing speed, as execution time also depends on the instructions being executed.

The process of starting the fetch-execute cycle in a processor is complex and hardware-dependent. Engineers may use a reset option or combinational circuits to initiate the cycle. This initiation process, known as bootstrapping, involves loading the program from memory. In embedded systems, the program is typically stored in read-only memory, while conventional computers load the operating system from an input/output device.

Many devices feature soft power switches that act as sensors for the processor to determine the correct booting device. The soft switch does not directly turn the device on or off but aids in the booting process. This method is common in modern devices and plays a crucial role in initiating the fetch-execute cycle.

In summary, a processor is a digital device capable of performing computations through multiple steps. It can adjust parameters and execute programmable logic, serving as an engine for controlling the fetch-execute cycle. Processors come in various classifications, but their primary goal remains to manage the execution cycle efficiently.