Guide to Operating Systems, 4 th ed.

1. Guide to Operating Systems, 4th ed. Chapter 3: Operating Systems Hardware Components

2. Explain operating system hardware components, which will include design type, speed, cache, address bus, data bus, control bus, and CPU scheduling Describe the basic features and system architecture of popular PC processors Understand how hardware components interact with operating systems Objectives Guide to Operating Systems, 4th ed. 2

3. Understanding CPUs One of the main functions of the OS is to provide the interface between the various application programs running on a computer and the hardware inside. The system architecture of the computer is built around the CPU. Includes the number and type of CPUs in the hardware, and the communications routes (buses) between CPUs and other hardware components. The CPU is the chip that performs the actual computational and logic work. Most modern PCs have one such chip (Single-Core Processors). Guide to Operating Systems, 4th ed.

4. Understanding CPUs The CPU is the chip that performs the actual computational and logic work. Most modern PCs have one such chip (Single-Core Processors). For complete functionality, the CPU requires several support chips to help manage communications with devices and device drivers. Core – section of the processor that actually does the reading and execution of instructions Processors originally only had one core Multicore processor has two or more cores Guide to Operating Systems, 4th ed.

5. Understanding CPUs A processor is the part of the CPU that reads and executes very basic instructions. Processors were originally created to have only one core to perform one instruction at a time. The core is the section of the processor that actually does the reading and executing of instructions. A multicore processor has two or more cores. Dual-core processor – two cores Quad-core processor – four cores A Multiprocessor computer has multiple physical CPU chips Guide to Operating Systems, 4th ed.

6. Understanding CPUs CPUs can be classified by hardware elements: Design type Speed Cache Address bus Data bus Control bus CPU scheduling Guide to Operating Systems, 4th ed.

7. Design Type Two general CPU designs are used today: Complex Instruction Set Computing (CISC) Reduced Instruction Set Computing (RISC) Main difference between the two design types is the number of different instructions the chip can process CPUs can process as many as 20 million (low-end) to several billion (high-end) operations per second Clock speed and CPU design are the factors that determine how fast operations are executed. Instruction set – The list of commands the CPU can understand and carry out Guide to Operating Systems, 4th ed.

8. Design Type How a CISC CPU operates When the CPU gets a command it assigns specific instructions to different parts of the chip When a command is finished and the next command is received, the CPU uses the same parts of the chip it used before CISC-based chips recognize more than 200 different instructions. The Intel x86 family of computers is based on the CISC CPU. Advantages of CISC: Only needs general-purpose hardware to carry out commands versus hardware designed for a specific purpose Chip is driven mainly by software, which is cheaper to produce Guide to Operating Systems, 4th ed.

9. Design Type Disadvantages of CISC: The complexity of hardware needed to perform many functions The complexity of on-chip software needed to make the hardware do the right thing. The need to continually reprogram the on-chip hardware. If you use the same part of the chip to add a number as you use to multiply a number, you must reconfigure the hardware in between the multiplication and addition operations. CISC chips can be a little slower than RISC chips When you use general-purpose hardware to perform specific functions, the functions won’t always be executed in the most efficient way. Can slow the CPU’s execution of program code. Solution – Customize hardware for specific functions. Guide to Operating Systems, 4th ed.

10. Design Type Disadvantages of CISC CPU Example – A math coprocessor can be added in order to help perform all computational functions Increases CPU performance Also increases the price Guide to Operating Systems, 4th ed.

11. Design Type How a RISC CPU operates Requires very little setup for specific tasks because it has hardware on the chip that is specially designed and optimized to perform particular functions. Disadvantage - Need more hardware to carry out instructions which makes the chip more expensive. This is the main reason a RISC CPU has so few instructions – most of the instructions it performs are conducted by hardware on the chip that is dedicated to perform just that function. Because most of the hardware on the RISC CPU is not shared among many instructions, RISC CPUs typically use a technique called pipelining Allows the processor to operate on one instruction while it is retrieving one or more instructions from the OS or application Approximately 95% of mobile phones worldwide use ARM (Advanced RISC Machine) chips. Guide to Operating Systems, 4th ed.

12. Design Type CISC versus RISC processing Guide to Operating Systems, 4th ed.

13. Design Type The RISC processor design has evolved into a concept called Explicitly Parallel Instruction Computing (EPIC) Created as a joint project by Intel and Hewlett-Packard (HP) Enables the processor to handle massive numbers of operations simultaneously by implementing large storage areas and executing parallel instruction sets A single processor can execute as many as 20 operations at a time. Chip can predict and speculate which operations are likely in the future. Through prediction and speculation, the chip actually performs some operations before they are requested. It sets up areas of memory (work areas) so that the tools needed for similar operations are already present, and those operations are handled one after another. Guide to Operating Systems, 4th ed.

14. Design Type RISC-based EPIC processors (continued) EPIC can support up to 256 64-bit registers More registers than CISC and RISC processors. Reduces or eliminates bottlenecks at the processor, which enables the processor to work faster. Can build three instructions into one “word” A word is like a single communication with the processor CISC and traditional RISC use one instruction per word. Enables the processor to work much faster. EPIC instructions can be combined into instruction groups, consisting of multiple “words” It attempts to execute all of the instructions in one group at the same time, if possible. The number of instructions in one instruction group is, theoretically, unlimited. Guide to Operating Systems, 4th ed.

15. Speed The speed of a CPU defines how fast it can perform operations Most obvious indicator is the internal clock speed The clock provides a rigid schedule to make sure all the chips know what to expect at what time The internal clock speed tells you how many clock pulses (ticks) are available per second The CPU performs some action on every tick. The more ticks/second, the faster the CPU executes commands and the harder the electronics on the CPU must work. Guide to Operating Systems, 4th ed.

16. Speed • As more components are needed to make a CPU, the chip uses more energy to do its work • Part of this energy is converted to heat. • CPUs require fans to keep cool. • The chips must be able to communicate with other chips in the computer • Uses the external clock speed of the computer to communicate with the rest of the computer • External clock speed runs slower than the internal clock speed • Typically one-half, on-third, one-fourth, or one-eighth the speed of the internal CPU clock • It would be extremely expensive to make every component in the computer run as fast as the CPU. • It is common practice to run the other components as a reduced clock rate. Guide to Operating Systems, 4th ed.

17. Cache Since the internal clock of a CPU is faster than the external clock the CPU would have to wait on information to arrive from other parts of the computer Most modern CPUs have cache memory built into the chip. This memory is extremely fast and typically runs at the same speed as the processor Level 1 (L1) cache Some CPUs have two or more levels of cache memory, called level 2 (L2) cache Normally runs at the same speed as the external CPU clock Some CPUs have level 3 (L3) cache on a separate chip. Guide to Operating Systems, 4th ed.

18. Cache In many cases, up to 90% of data the CPU needs to transfer to and from memory is present in the L1, L2/L3 cache Cache controller – predicts what data will be needed and makes the data available in cache before it is needed Intelligent, fast cache controllers and large amounts of L1, L2, and L3 help increase the speed of a CPU Guide to Operating Systems, 4th ed.

19. Address Bus Address Bus – An internal communications pathway that specifies the source and target addresses for memory reads and writes. Typically runs at the external clock speed of the CPU The address is conveyed in the form of a series of bits. The width of the address bus is the number of bits that can be used to address memory A wider bus means the computer can address more memory and store more data Most PCs use a 32-bit address bus Allows them to address 4 billion (4 GB) memory addresses Some newer processors use a 64-bit address bus Allows them to address 16 terabytes (TB) of memory Guide to Operating Systems, 4th ed.

20. Data Bus The data bus allows computer components, such as CPU, display adapter, and main memory, to share information The number of bits in the data bus indicates how many bits of data can be transferred from memory to the CPU in one clock tick. A CPU with an external clock speed of 1 GHz will have 1 billion ticks per second (1 byte = 8 bits; 1billion X 16 bits (16-bit data bus) / 8 bits/second = 2 GB/ second) A 64-bit data bus could transfer as much as 8 GB per second The software must be able to instruct the CPU to use all of the data bus; The rest of the computer must be fast enough to keep up with the CPU. Guide to Operating Systems, 4th ed.

21. Data Bus Most CPUs work internally with the same number of bits as on the data bus. A CPU with a 64-bit data bus typically can perform operations on 64 bits of data at a time. Almost all CPUs can be instructed to work with chunks of data narrower than the data bus width, but the CPU is not as efficient The same number of clock cycles is required to perform an operation, whether or not all bits are used. Windows Vista, Windows 7, Windows Server 2003/2008, MAC OS Leopard and Snow Leopard OSs include a 64-bit version. Guide to Operating Systems, 4th ed.

22. Control Bus • Information is transported on the control bus to keep the CPU informed about the status of resources and devices connected to the computer • Whether or not a particular resource is active and can be accessed. • Memory read and write status is transported on this bus, as well as interrupt requests (IRQs) • A request to the processor to “interrupt” whatever it is doing to take care of a process, which in turn might be interrupted by another process Guide to Operating Systems, 4th ed.

23. CPU Scheduling Determines which process to start given the multiple processes waiting to run. During DOS days, most OSs were single threaded. They would run just one process until it was completed and then turn to the next process. Beginning with Windows NT, the use of CPU scheduling algorithms began to evolve allowing multithreading The ability to run two or more processes (threads) at the same time Guide to Operating Systems, 4th ed.

24. Popular PC Processors • Intel – most popular CPU manufacturer today • 8088 – CPU found in the original IBM PC • Early Intel processors were identified by model numbers: 8088, 8086, 80286, 386, 486 (sometimes preceded by an i as in i486) • Pentium family of chips followed 486 and are sometimes identified by a P and a number (example – P4) • Intel Itanium and Itanium 2 are newer 64-bit processors for high-end PCs and server Guide to Operating Systems, 4th ed.

25. Popular PC Processors Single-core Intel CPUs Guide to Operating Systems, 4th ed.

26. Popular PC Processors Guide to Operating Systems, 4th ed.

27. Popular PC Processors Intel Itanium and Itanium 2 processors are different from previous ones in two respects: Built on the RISC-based EPIC architecture 64-bit chips In order to use the capabilities of 64-bit processing, the operating system and applications must be rewritten to use 64-bit processing Windows XP, Windows Server 2003 Enterprise, Windows Server 2003 Datacenter, and Windows Server 2008 can run on Itanium 64-bit processors Guide to Operating Systems, 4th ed.

28. Popular PC Processors Initially, processors were developed with one core. Where program instructions are executed. Today, some computers contain 6, 8, 12, 16, and even more cores. Guide to Operating Systems, 4th ed.

29. Popular PC Processors Multicore Intel CPUs Guide to Operating Systems, 4th ed.

30. Popular PC Processors Advanced Micro Devices, Inc. (AMD) – manufactures CPU chips that compete with Intel Single-core AMD processors Guide to Operating Systems, 4th ed.

31. Popular PC Processors Multicore AMD processors Guide to Operating Systems, 4th ed.

32. Popular PC Processors Motorola 68xxx – typically found in Macintosh computers and older UNIX computers (now discontinued) PowerPC – a new line of chips that used different instructions sets than the Motorola 68xxx line Developed jointly by Apple Computer, IBM, and Motorola (AIM) In 2005, Apple moved to using Intel chips SPARC – Scalable Processor Architecture A RISC processor designed by Sun Microsystems SPARC T3 is the current version of the SPARC processor A 64-bit chip with 64-bit address and data buses Guide to Operating Systems, 4th ed.

33. Popular PC Processors Alpha – CPU originally designed by Digital Equipment Corporation (DEC), which was purchased by Compaq, which was purchased by HP Found in older high-end HP Compaq servers Has a 64-bit data and address bus Was the first chip to reach a speed of 1 GHz Found in computers conducting heavy networking, engineering, and graphics duties There were many proprietary devices (file servers, firewalls, and routers) that ran custom operating systems based on the Alpha architecture Guide to Operating Systems, 4th ed.

34. Chapter Summary • Hardware and operating systems are interrelated because in many ways they grew up together. Processor hardware improvements have marched steadily from the early 8088 chip to the modern 64-bit multicore processors. Operating systems paralleled these changes to take advantage of the capabilities at each stage of development. • The early computer operating systems were well suited to the early processors. As processors became faster and more advanced, so did operating systems. • Today, 64-bit processors provide a foundation for operating systems like Windows 7, Mac OS X Snow Leopard, and Linux/Fedora to take advantage of high-speed networking and multimedia capabilities. Multicore processors bring greater capabilities and functionality to server operating systems. Guide to Operating Systems, 4th ed.