Summary COS2621 Notes.

Summary 1.1 Organization and Architecture Computer architecture - refers to those attributes of a system visible to a programmer, ie: those attributes that have a direct impact on the logical execution of a program. Examples are: instruction set, number of bits used to represent various data types, I/O mechanisms, and techniques for addressing memory. Computer organization - refers to the operational units and their interconnections that realize the architectural specifications. Examples are: hardware details transparent to the programmer such as - control signals, interfaces between the computer and peripherals, and the memory technology used. The distinction between architecture and organization is important. Manufacturers offer a family of computer models with the same architecture, but with differences in organization. Different models in the family have different price and performance characteristics. A particular architecture may span many years, with its organization changing with changing technology. 1.2 Structure and Function Structure - The way in which the components are interelated. Function - The operation of each individual component as part of the structure. Function There are four basic functions that a computer can perform - • Data processing - Computer must be able to process data; • Data storage - Must be able to store data that is being processed, as well as long-term storage; • Data movement - Must be able to move data between itself and the outside world. When data are received or delivered to a device that is directly connected to the computer, the process is known as input-output (I/O), and the device is referred to as a peripheral. When data are moved over longer distances, to or from remote devices, the process is known as data communications. • Control - Must be control of above 3 functions. Ultimately control is exercised by the programmer, who provides computer with instructions. Within the computer a control unit manages the computers' resources, in response to those instructions. Structure Four main structural components - (There may be one or more of each) • Central Processing Unit (CPU) - Controls the operation of the computer and performs its data processing functions; Chapter 1 - Introduction COS2621 Notes. ◦ Control unit - Controls the operation of the CPU and hence the computer; ◦ Arithmetic and logic unit (ALU) - Performs the computers' data processing functions; ◦ Registers - Provides storage internal to the CPU; ◦ CPU interconnection - Mechanism that provides for communication among the control unit, ALU, and registers. • Main memory - Stores data; • I/O - Moves data between the computer and its external environment; • System interconnection - provides for communication among CPU, main memory, and I/O - system bus. 0.3 Why study Computer Organization & Architecture ? (Read Appendix B: Assembly Language - Text book) Computer organization and architecture encompasses a broad range of design issues and concepts. A good overall understanding of these concepts will be useful in other areas of study and work. Why study Assembly language - • Assembly language code is often much smaller and faster than code written in a high-level language; • We could speed up the execution time of a program if those parts of the program that are performed frequently are written in assembly language; • With assembly language programming we have complete access to hardware. This is not possible with high-level languages; • A basic understanding of low-level programming is essential for understanding the intricacies of compilers and operating systems; • It is easier to understand the operation of a computer at the architctural level if we have knowledge of assembly language. Chapter 1 - Introduction Key Terms • arithmetic and logic unit (ALU) - A part of a computer that performs arithmetic operations, logic operations, and related operations. • central processing unit (CPU) - Controls the operaton of a computer, and performs its data processing functions. • computer architecture - refers to those attributes of a system visible to a programmer, ie: those attributes that have a direct impact on the logical execution of a program. • computer organization - refers to the operational units and their interconnections that realize the architectural specifications. • control unit - Controls the operation of the CPU, and hence the computer. • input-output (I/O) - Refers to the movement of data between a computer and a directly attached peripheral, or other remote devices. • main memory - Program addressable storage from which instructions and other data can be loaded directly into registers for subsequent execution or processing • processor - See Central Processing Unit (CPU). • registers - Provide storage internal to the CPU. • system bus - Interconnection between CPU, main memory, and I/O; consisting of a number of conducting wires attached to all the other components. --ooOoo--