Computer Structure and Function PDF

Computer Structure and Function Dr. Davies Rene Segera Department of Electrical and Information Engineering University of Nairobi Computer Structure and Function University of Nairobi Objective Objective To underst...

Computer Structure and Function Dr. Davies Rene Segera Department of Electrical and Information Engineering University of Nairobi Computer Structure and Function University of Nairobi Objective Objective To understand the basic structure and function of computer systems, focusing on how different parts interact to process, store, move, and control data. Learning Outcomes Identify the hierarchical structure of computer systems. Describe the main components of a computer and their functions. Explain the roles of different levels of memory, including cache. Understand the concept of multicore processors. Discuss examples of real-world computer structures, such as the IBM z13 processor. 1 Introduction to Structure and Function A computer is a complex system with millions of electronic parts. To understand comput- ers, we look at them as hierarchical systems—each main part contains smaller parts working together. This approach makes it easier to design and explain computer systems by looking at different levels one at a time. 1.1 Key Terms Structure: How parts are connected. Function: The role of each part in the system. Computers have four main functions: 1. Data Processing: Computers can perform various types of data processing. 2. Data Storage: Computers store data temporarily (short-term) or permanently (long-term). 3. Data Movement: Data moves between computers and other devices (like USB drives or networks). 4. Control: The control unit directs operations within the computer. 1 Computer Structure and Function University of Nairobi 2 Internal Structure of Computers 2.1 Simple Single-Processor Computer Central Processing Unit (CPU): Manages data processing and controls the com- puter. Main Memory: Stores data for the computer to use. Input/Output (I/O): Moves data between the computer and external devices. System Interconnection: Allows communication among CPU, memory, and I/O, often through a system bus (a set of wires for data transfer). Figure 1.1 : Top-Level Structure of a traditional single-processor computer. 2 Computer Structure and Function University of Nairobi 2.2 Multicore Computers A core is an individual processing unit in a processor. Multicore processors (like those with 8 cores in Figure 1.2 ) have multiple cores on a single chip, each performing tasks. Cache Memory: A fast, small memory located close to the CPU that holds frequently used data. 2.3 Motherboard The motherboard holds the processor, memory chips, and other key parts. It includes slots for PCI-Express, Ethernet, USB, and SATA connections. Figure 1.3 : Motherboard with two Intel Quad-Core Xeon processors. 3 Computer Structure and Function University of Nairobi 3 Processor Chip and Core Structure Each core has: Instruction Logic: Manages instruction fetching and decoding. Arithmetic and Logic Unit (ALU): Executes mathematical operations. Load/Store Logic: Handles data transfers between memory and cache. Figure 1.4 : Simplified layout of an IBM z13 processor unit with 8 cores and an L3 cache. 4 Computer Structure and Function University of Nairobi 3.1 Detailed Core Structure (IBM z13) Figure 1.5 : Displays the IBM z13 core layout, highlighting specialized units: ISU (Instruction Sequence Unit): Determines the sequence in which instructions are executed in a superscalar architecture, enabling out-of-order (OOO) execution. It tracks register names, OOO instruction dependencies, and manages resource dispatch. IFB (Instruction Fetch and Branch): Manages instruction fetching and branching, containing a 128-kB instruction cache, branch prediction logic, and buffers. ICM (Instruction Cache and Merge): Works alongside IFB to manage the instruc- tion cache, merging and controlling instruction fetching based on branch predictions. IDU (Instruction Decode Unit): Receives instructions from IFB buffers and de- codes z/Architecture operation codes, preparing them for execution. LSU (Load-Store Unit): Contains a 96-kB L1 data cache and handles data traffic between the L2 cache and execution units. It manages all operand accesses, including different data lengths, modes, and formats. XU (Translation Unit): Translates logical addresses from instructions into physical addresses in main memory. It includes a translation lookaside buffer (TLB) to speed up memory access. PC (Core Pervasive Unit): Used for instrumentation and error collection within the core. 5 Computer Structure and Function University of Nairobi FXU (Fixed-Point Unit): Executes fixed-point (integer) arithmetic operations. VFU (Vector and Floating-Point Units): Manages vector and floating-point op- erations. It handles binary and hexadecimal floating-point operations, fixed-point mul- tiplication, and decimal arithmetic on numbers stored as decimal digits. RU (Recovery Unit): Maintains a backup of the system’s state, including registers, and manages hardware fault recovery. COP (Dedicated Co-Processor): Performs data compression and encryption, en- hancing security and efficiency in data handling. L2D (L2 Data Cache): A 2-MB cache that stores data for memory traffic other than instructions, speeding up access to frequently used data. L2I (L2 Instruction Cache): A 2-MB cache dedicated to storing instructions, im- proving processing speed by reducing access times for frequently executed instructions. 4 Key Takeaways Key Takeaways Computers operate using four main functions: data processing, storage, move- ment, and control. Computers are structured in a hierarchy, making it easier to design and under- stand. The CPU is central to processing, while memory and I/O support data storage and movement. Multicore processors improve performance by using multiple cores on a single chip. Cache memory boosts processing speed by storing frequently accessed data close to the CPU. 5 Exam-Based Questions Q1: Define structure and function in the context of computer systems. Q2: What is the difference between data processing and data storage? Q3: Explain the role of the control unit in a computer. 6  Computer Structure and Function University of Nairobi Q4: Describe the purpose of a system bus. Q5: What is the function of main memory in a computer? Q6: Define a multicore processor and its benefits. Q7: How does cache memory enhance computer performance? Q8: What are the primary components of a single-processor computer? Q9: Explain the term hierarchical system in computer design. Q10: What does a motherboard do in a computer? Q11: Describe the purpose of PCI-Express slots on a motherboard. Q12: How does the Arithmetic and Logic Unit (ALU) function in a CPU? Q13: What is the role of the L3 cache in multicore processors? Q14: Explain how instruction logic helps in executing programs. Q15: Discuss the significance of the IBM z13 processor in understanding core design. 7