Computer Architecture

Size: px

Start display at page:

Download "Computer Architecture"

Marsha Fletcher
7 years ago
Views:

1 Chapter 1 Computer Architecture Introduction to Computer Architecture Bryar M. Shareef (bryarmustafa.epu.edu.krd)

2 Fundamental Concepts What is a computer architecture? Computer Architecture: The science and art of designing, selecting, and interconnecting hardware components and designing the hardware/software interface to create a computing system that meets functional, performance, energy consumption, cost, and other specific goals. Von Neumann architecture The template for all modern computers is the Von Neumann architecture, detailed in a 1945 paper by Hungarian mathematician John von Neumann. This describes a design architecture for an electronic digital computer with subdivisions of a processing unit consisting of an arithmetic logic unit and processor registers, a control unit containing an instruction register and program counter, a memory to store both data and instructions, external mass storage, and input and output mechanisms. 2

3 Figure 1.1: Von Neumann architecture Introduction to Computer Architecture Computer Organization vs. Architecture Computer Architecture refers to those attributes of a system that have a direct impact on the logical execution of a program. Examples: 1. the instruction set 2. the number of bits used to represent various data types 3. I/O mechanisms 4. memory addressing techniques Computer Organization refers to the operational units and their interconnections that realize the architectural 3

4 specifications. Examples are things that are transparent to the programmer: So, for example, It is an architectural design issue whether a computer will have a multiply instruction. It is an organizational issue whether that instruction will be implemented by a special multiply unit or by a mechanism that makes repeated use of the add unit of the system. Many computer manufacturers offer a family of computer models, all with the same architecture but with differences in organization. Why Study Computer Architecture? 1. Enable better systems: make computers faster, cheaper, smaller, more reliable, By exploiting advances and changes in underlying technology/circuits 2. Enable new applications Life-like 3D visualization 20 years ago? Chemist, medicine. 3. Enable better solutions to problems Software innovation is built into trends and changes in computer architecture E.g. >50% performance improvement per year has enabled this innovation 4. Understand why computers work the way they do 5. Understand where computers are going Future capabilities drive the (computing) world 4

5 Real world-impact: no computer architecture! no computers! Structure and Function 1. Structure: The way in which the components are interrelated 2. Function: The operation of each individual component as part of the structure. Structure Figure 1.2 is the simplest possible depiction of a computer. The computer interacts in some fashion with its external environment. In general, all of its linkages to the external environment can be classified as peripheral devices or communication lines. We will have something to say about both types of linkages. 5

6 There are four main structural components: Central processing unit (CPU): Controls the operation of the computer and performs its data processing functions; often simply referred to as processor. Main memory: Stores data. I/O: Moves data between the computer and its external environment. System interconnection: Some mechanism that provides for communication among CPU, main memory, and I/O. A common example of system CPU major components are: Control unit: Controls the operation of the CPU and hence the computer Arithmetic and logic unit (ALU): Performs the computer s data processing functions Registers: Provides storage internal to the CPU CPU interconnection: Some mechanism that provides for communication among the control unit, ALU, and registers. 6

7 Figure 1.2: CPU major parts Functions: Basic functions that a computer can perform: 1. Data Processing - a wide variety of forms, but only a few fundamental methods or types 2. Data Storage - long-term or short, temporary storage 3. Data Movement: The computer must be able to move data between itself and the outside world. 4. Control - of the above functions, by instructions provided by the user of the computer (i.e. their programs) 7

8 Fig 1.3 Functional View of computer Figures (a-d) shows the four possible types of operations. 1. The computer can function as a data movement device (Figure a), simply transferring data from one peripheral or communications line to another. 8

2. It can also function as a data storage device (Figure b), with data transferred from the external environment to computer storage (read) and vice versa (write). 3.

9 2. It can also function as a data storage device (Figure b), with data transferred from the external environment to computer storage (read) and vice versa (write). 3. The final two diagrams show operations involving data processing, on data either in storage (Figure c) 4. en route between storage and the external environment (Figure d). Operations (Fig. 1.4: a) Data movement 9

10 Operations (Fig. 1.4: b) Storage Operation (Fig. 1.4: c) Processing from/to storage 10

11 Operation (Fig. 1.4: d) Processing from storage to I/O 11

12 Instruction Set Architecture (ISA) The instruction set, also called instruction set architecture (ISA), is part of a computer that pertains to programming, which is basically machine language. The instruction set provides commands to the processor, to tell it what it needs to do. The instruction set consists of addressing modes, instructions, native data types, registers, memory architecture, interrupt, and exception handling, and external I/O. CISC vs RISC Until the early 1980s, all CPUs, whether single-chip or whole-board, followed the CISC (complex instruction set computer) design philosophy. CISC refers to CPUs with hundreds of instructions designed for every possible situation. To design CPUs with so many instructions 12

13 consumed not only hundreds of thousands of transistors, but also made the design very complicated, time-consuming, and expensive. In the early 1980s, a new CPU design philosophy called RISC (reduced instruction set computer) was developed. The proponents of RISC argued that no one was using all the instructions etched into the brain of CISC-type CPUs. Why not streamline the instructions by simplifying and reducing them from hundreds to around 40 or so and use all the transistors that are saved to enhance the power of the CPU? Although the RISC concept had been explored by computer scientists at IBM as early as the 1970s, the first working single-chip RISC microprocessor was implemented by a group of researchers at the University of California at Berkeley in1980. Today the RISC design philosophy is no longer an experiment limited to research laboratories. Since the late 1980s, many companies designing new CPUs (either single-chip or whole-board) have used the RISC philosophy. It appears that eventually the only CISC microprocessors remaining in use will be members of the 80x86 family (8086, 8088, 80286, 80386, 80486, 80586, etc.) and the 680x0 family (68000, 68010, 68020, 68030, 68040, 68050, etc.). The 80x86 will be kept alive by the huge base of IBM PC, PS, and compatible computers, and the Apple Macintosh is prolonging the life of 680x0 microprocessors. The Apple Company in 2005 announced that the company would make a transition from the use of PowerPC microprocessors supplied by Freescale (formerly Motorola) and IBM in its Macintosh computers, to processors designed and manufactured by Intel, a chief supplier for most of Apple's competitors CISC RISC Used in laptops and desktop computers, made by intel or AMD Has more complex hardware Used in smartphones and tablets, based around ARM processor Has simpler hardware 13

14 Multiple machine cycles per instruction Physically larger in size and require more silicon to make thus more expensive Greater energy consumption More intensive tasks will do better with CISC Cannot support pipelining Single machine cycle per instruction Smaller in size as less complex circuitry required, less silicon needed to make thus cheaper Lower energy requirements, and can go into sleep mode when not actively processing Run at lower clock speed, but can perform simpler tasks more quickly than CISC Can support pipelining 14

Chapter 2 Logic Gates and Introduction to Computer Architecture

Chapter 2 Logic Gates and Introduction to Computer Architecture 2.1 Introduction The basic components of an Integrated Circuit (IC) is logic gates which made of transistors, in digital system there are