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Types of Computers. Super Computers Mainframes Mini Computers Micro Computers. The Computer System. Hardware Software Users Data . Communication Devices. Secondary Storage Magnetic Disk, Optical disk, Magnetic Tape. Central Processing Unit. Buses. Primary Storage.
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Types of Computers • Super Computers • Mainframes • Mini Computers • Micro Computers
The Computer System • Hardware • Software • Users • Data
Communication Devices Secondary Storage Magnetic Disk, Optical disk, Magnetic Tape Central Processing Unit Buses Primary Storage Input devices Keyboard, mouse, touch screen, source data automation Output Devices Printers, Video Display terminals, Plotters, Audio Output Hardware Components of A computer
Processing • Sequential Processing • Reduced Instruction Set Computers (RISC) • Faster • Conventionally Complex Instruction Set Computing • Parallel Processing • Multiple CPUs – Break a problem into several smaller problems and work simultaneously • Massively Parallel Processing (MPP) • 100s or 1000s o chips to break problem into smaller processes Moving Beyond…… Cluster Computing
SEQUENTIAL PROCESSING PARALLEL PROCESSING Program Program CPU CPU task1 CPU task2 CPU task3 CPU task4 CPU task5 RESULT RESULT
The Processor Introduction To Personal Computing
Looking Inside the Machine - The CPU • The procedure that transforms raw data into useful information is called processing. This function is divided between the computer's processor and memory. • The processor is also called the central processing unit (CPU). It manages all devices and performs the actual processing of data. • The CPU consists of one or more chips attached to the computer's main circuit board (the motherboard).
The Central Processing Unit Control Unit ALU registers Output Input Communication Devices Primary Memory Secondary Storage
Dual Core Processors • A dual core processor is a CPU with two separate cores, each with its own cache. It's the equivalent of getting two microprocessors in one. • In a single-core or traditional processor the CPU is fed instructions, it must order, execute, then selectively store in its cache for quick retrieval. When data outside the cache is required, it is retrieved through the system bus from random access memory (RAM) or from storage devices. Accessing these slows down performance to the maximum speed the bus, RAM or storage device will allow, which is far slower than the speed of the CPU. The situation is compounded when multi-tasking. In this case the processor must switch back and forth between two or more sets of data streams and programs. CPU resources are depleted and performance suffers. • In a dual core processor each core handles incoming data simultaneously to improve efficiency. Just as two heads are better than one, so are two hands. Now when one is executing the other can be accessing the system bus or executing its own code. Adding to this favorable scenario, both AMD and Intel's dual-core flagships are 64-bit.
To utilize a dual core processor, the operating system must be able to recognize the cores and the software must have simultaneous multi-threading technology (SMT) written into its code. SMT enables parallel multi-threading wherein the cores are served multi-threaded instructions in parallel. Without SMT the software will only recognize one core. Adobe Photoshop is an example of SMT-aware software. SMT is also used with multi-processor systems common to servers. • A dual core processor is different from a multi-processor system. In the latter there are two separate CPUs with their own resources. In the former, resources are shared and the cores reside on the same chip. A multi-processor system is faster than a system with a dual core processor, while a dual core system is faster than a single-core system, all else being equal. • An attractive value of dual core processors is that they do not require a new motherboard, but can be used in existing boards that feature the correct socket. For the average user the difference in performance will be most noticeable in multi-tasking until more software is SMT aware. Servers running multiple dual core processors will see an appreciable increase in performance. • Multi-core processors are the goal and as technology shrinks, there is more "real-estate" available on the die. In the fall of 2004 Bill Siu of Intel predicted that current accommodating motherboards would be here to stay until 4-core CPUs eventually force a changeover to incorporate a new memory controller that will be required for handling 4 or more cores.
. Taking Advantage of Dual-core TechnologyA dual-core processor has many advantages especially for those looking to boost their system's multitasking computing power. Dual-core processors provide two complete execution cores instead of one, each with an independent interface to the frontside bus. Since each core has its own cache, the operating system has sufficient resources to handle intensive tasks in parallel, which provides a noticeable improvement to multitasking. Complete optimization for the dual-core processor requires both the operating system and applications running on the computer to support a technology called thread-level parallelism, or TLP. Thread-level parallelism is the part of the OS or application that runs multiple threads simultaneously, where threads refer to the part of a program that can execute independently of other parts. Key Terms To Understanding Dual-coredual-coreDual-core refers to a CPU that includes two complete execution cores per physical processor. • Even without a multithread-enabled application, you will still see benefits of dual-core processors if you are running an OS that supports TLP. For example, if you have Microsoft Windows XP (which supports multithreading), you could have your Internet browser open along with a virus scanner running in the background, while using Windows Media Player to stream your favorite radio station and the dual-core processor will handle the multiple threads of these programs running simultaneously with an increase in performance and efficiency.
Today Windows XP and hundreds of applications already support multithread technology, especially applications that are used for editing and creating music files, videos and graphics because types of programs need to perform operations in parallel. As dual-core technology becomes more common in homes and the workplace, you can expect to see more applications support thread-level parallelism. • Intel & AMD Dual-core Desktop ProcessorsThe Intel Pentium Processor Extreme Edition 840 running at 3.2 GHz and Intel 955X Express Chipsets are being built into computers that are now entering the market. This is Intel's first desktop dual-core product supporting Hyper-Threading Technology. Processor features include the following: • Hyper-Threading Technology: Enables you to run multiple demanding applications at the same time. • Intel Extended Memory 64 Technology: Provides flexibility for future applications that support both 32-bit and 64-bit computing. • Dual-Core: Two physical cores in one processor support better system responsiveness and multi-tasking capability than a comparable single core processor. [Source: Intel Dual-core Desktop Processor] • AMD also announced its line of desktop dual-core processors, the AMD Athlon 64 X2 processor family. The initial model numbers in the new family include the 4200+, 4400+, 4600+ and 4800+ (2.2GHz to 2.4GHz).The processors are based on AMD64 technology and are compatible with the existing base of x86 software, whether single-threaded or multithreaded. Software applications will be able to support AMD64 dual-core processors with a simple BIOS upgrade and no substantial code changes. [Source: AMD Dual-core Desktop Processor] • Both companies have also announced or released dual-core processors for servers and workstations as well.
How Computers Process Data – • Where Processing Occurs • Processing takes place in the PC's central processing unit (CPU). • The system's memory also plays a crucial role in processing data. • Both the CPU and memory are attached to the system's motherboard, which connects all the computer's devices together, enabling them to communicate.
How Computers Process Data – The Role of Memory • RAM stores data and program code needed by the CPU. The contents of RAM change rapidly and often. • Read-only memory (ROM) is nonvolatile (or permanent). It holds instructions that run the computer when the power is first turned on. • The CPU accesses each location in memory by using a unique number, called the memory address.
Looking Inside the Machine – How Memory is Measured • The smallest usable unit of measure for memory is the byte – the amount of memory required to hold one character, like the letter A or the numeral 2. • Computers work with larger chunks of data, measured in multiple bytes, as shown below: Unit Approx. Value Actual Value (bytes) (bytes) Kilobyte (KB) 1,000 1,024 Megabyte (MB) 1,000,000 1,048,576 Gigabyte (GB) 1,000,000,000 1,073,741,824 Terabyte (TB) 1,000,000,000,000 1,099,511,627,776
Looking Inside the Machine - Storage Devices • Storage devices hold data not currently being used by the CPU. Data is commonly stored on a magnetic or optical disk. Each type uses a special medium for storing data on its surface. • A disk drive is a device that reads data from and writes data to a disk. Most new computers feature a floppy disk drive, a hard disk drive, and an optical disk drive. • The most common optical storage devices are CD-ROM and DVD-ROM drives.
Factors Affecting Processing Speed • Registers • RAM • The System Clock • The Bus • Cache Memory
Factors Affecting Processing Speed – Registers • The CPU contains a number of small memory areas, called registers, which store data and instructions while the CPU processes them. • The size of the registers (also called word size) determines the amount of data with which the computer can work at a one time. • Today, most PCs have 32-bit registers, mean the CPU can process four bytes of data at one time. Register sizes are rapidly growing to 64 bits.
Factors Affecting Processing Speed – RAM • The amount of RAM in a PC has a direct affect on the system's speed. • The more RAM a PC has, the more program instructions and data can be held in memory, which is faster than storage on disk. • If a PC does not have enough memory to run a program, it must move data between RAM and the hard disk frequently. This process, called swapping, can greatly slow a PC's performance.
Factors Affecting Processing Speed – The System Clock • The computer's system clock sets the pace for the CPU by using a vibrating quartz crystal. • A single "tick" of the clock is the time required to turn a transistor off and back on. This is called a clock cycle. • Clock cycles are measured in Hertz (Hz), a measure of cycles per second. If a computer has a clock speed of 300 MHz, then its system clock "ticks" 300 million times every second. • The faster a PC's clock runs, the more instructions the PC can execute each second.
Factors Affecting Processing Speed – The Bus • A bus is a path between the components of a computer. Data and instructions travel along these paths. • The data bus' width determines how many bits can be transmitted between the CPU and other devices. • The address bus runs only between the CPU and RAM, and carries nothing but memory addresses for the CPU to use. • Peripheral devices are connected to the CPU by an expansion bus.
Factors Affecting Processing Speed – Cache Memory • Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU. • Cache is located directly on the CPU or between the CPU and RAM, making it faster than normal RAM. • CPU-resident cache is called Level-1 (L1) cache. External cache is called Level-2 (L2) cache. • The amount of cache memory has a tremendous impact on the computer's speed.
Extending the Processor's Power to Other Devices • Ports • Expansion Slots and Boards
Extending the Processor's Power • to Other Devices – Ports • External devices—such as those used for input and output—are connected to the system by ports on the back of the computer. • PCs feature a number of built-in ports, which are ready to accept devices such as a printer, mouse, keyboard, phone line, microphone and speakers, and others. • Most computers come with a serial port and a parallel port. A serial port transmits one bit of data at a time; a parallel port transmits data one byte at a time.
Adding Other Devices – Expansion Slots and Boards • If the PC does not have a port for an external device, you can install an expansion board into one of the empty expansion slots. • A board provides the correct port for the new device, and connects the device to the CPU by way of the computer's expansion bus. • Newer bus technologies such as Universal Serial Bus (USB) and IEEE 1394(Firewire) enable many devices to be connected to one port. • Small Computer System Interface (SCSI) is an older standard for extending the bus to multiple devices through a single port.