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Plug ‘n Play, Semiconductors, Bits and Transistors. Dr. Harold D. Camp IT 212 002 8 February 2007. Components of a Normal PC. http://computer.howstuffworks.com/pci.htm. Hardware Interrupts. Press the “A” Key. When you press the A key An electrical signal travels along a circuit
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Plug ‘n Play, Semiconductors, Bits and Transistors Dr. Harold D. Camp IT 212 002 8 February 2007
Components of a Normal PC • http://computer.howstuffworks.com/pci.htm
Press the “A” Key • When you press the A key • An electrical signal travels along a circuit • Identifies what key you pressed • The keyboard interrupt arrives on one of 16 interrupt request (IRQ) lines • Seven of the IRQs monitor specific components, such as the keyboard controller • The controller relays a signal to a subsystem called the interrupt controller • Runs interference between the CPU and 256 possible kinds of interrupts. • The other interrupt circuits keep an eye on the input/output bus • Includes the computer's expansion slots • More than one expansion card on the Peripheral Component Interconnect (PCI) and PCI-Express slots use the same IRQ • The requests are managed by the Plug 'n' Play function • The interrupt controller sends a signal to the INTR pin • Sticks out of the bottom of the CPU • Used for normal interrupt signals • There's also an pin NMI, for non-maskable interrupts • Such as the one generated by pressing Ctrl+Alt+Del
Press the “A”Key • The CPU puts whatever it was doing on hold • Memory address written to a stack. • To remind the CPU later where it left off from its previous task • Two methods of controlling the CPU: polling and interrupts. • Polling goes from task to task endlessly, asking if they need anything from the CPU • If a task needs something, the other tasks have to wait until that task was completed • Not very efficient • Interrupts, the CPU goes about her work until an external task issues an interrupt • The interruption gets immediate attention, at least until another external task needs something • Interrupts are the preferred method of handling requests from software and hardware • The CPU checks to find out what key you pressed • Rather than display the letter, the CPU checks the interrupt descriptor table (IDT). • The CPU performs the instructions at the IDT's locations associated with the A key • The CPU calls an interrupt service routine (IRS) to tell the CPU what to do when • Allows programmers to replace the normal instructions with another program • In a game, pressing the A key could make a character move left, W move up, and so on • When the IRS completes its job, the CPU executes a return from interrupt (RET) • Tells the CPU to return to whatever it was doing before it was interrupted • The CPU pulls the last memory location off the stack and processes the next instructions
Busses • Power and speed of computer components increased at a steady rate since desktop computers were first developed • Software makers create new applications capable of utilizing the latest advances in processor speed and hard drive capacity • Hardware makers rush to improve components and design new technologies to keep up with the demands of software • The bus • Essentially, a channel or path between the components in a computer • Having a high-speed bus important • Many different types of buses • We concentrate on the Peripheral Component Interconnect (PCI) bus • The idea of a bus is simple • Lets you connect components to the computer's CPU. • Hard disks, memory, sound systems, video systems and so on • For example, you need special hardware to drive the screen • The screen is driven by a graphics card • A small printed circuit board designed to plug into the bus
Bus Connections • A typical PC today has two main buses: • System or local bus • Connects the microprocessor (CPU) and the system memory • Fastest bus in the system • A slower bus for communicating with hard disks and sound cards • Connect to the system bus through a bridge, part of the computer's chipset • Acts as a traffic cop • A bus makes parts more interchangeable • If you want a better graphics card • Unplug the old card from the bus • Plug in a new one • If you want two monitors on your computer • Plug two graphics cards into the bus
PCI Bus • Along came PCI • Early 1990s, Intel introduced a new bus standard • Peripheral Component Interconnect (PCI) bus • A hybrid between ISA and VL-Bus • Direct access to system memory for connected devices • Uses a bridge to connect to the system bus and the CPU • Capable of even higher performance than VL-Bus and • Eliminates interference with the CPU • The system bus physically connects the processor to most of the other components in the computer • Including main memory (RAM), hard drives and PCI slots • The system bus usually operates at 400-MHz to 800-MHz. • There are other buses as well • Universal Serial Bus (USB) • Connects things like cameras, scanners and printers • A thin wire to connect to the devices • Many devices can share that wire simultaneously • Firewire is another bus • Used mostly for video cameras & external hard drives
Variety of Busses • Original PC bus (circa 1982) • 16 bits wide • Operated at 4.77 MHz • Known as the ISA bus • Data rate of up to 9 MBps (megabytes per second) • Fast enough for today's applications • ISA remained in use even after more advanced technologies were available • Long-term compatibility with a large number of hardware manufacturers • Before the rise of multimedia • Technology advanced and ISA failed to keep up • Extended Industry Standard Architecture (EISA) • 32 bits at 8 MHz • Vesa Local Bus (VL-Bus). • 32 bits wide and the speed of the system bus • Essentially tied directly into the CPU • Connecting more than two devices to the VL-Bus caused interference with CPU performance • VL-Bus was typically used only for connecting a graphics card
Backside Bus • The backside bus • A separate connection between the processor and the Level 2 cache • Operates faster than frontside bus • Same speed as the processor • Caching works efficiently as possible. • Backside buses evolved over years • In 1990s, backside bus was a wire • Connected CPU to an off-chip cache • Cache was a separate chip • Required expensive memory • Since then, the Level 2 cache is integrated into the microprocessor • Smaller and cheaper
Plug ‘n Play Bus • PCI connects more devices VL-Bus • Up to five external components • Each of the five connectors can handle two fixed devices on the motherboard • You can have more than one PCI bus on the same computer • PCI bridge chip regulates the speed of the PCI bus independently of the CPU • Provides higher reliability • Ensures PCI-hardware manufacturers know exactly what to design for. • PCI originally operated at 33 MHz using a 32-bit-wide path, revisions include • Increasing the speed from 33 MHz to 66 MHz • Doubling the bit count to 64 • PCI-X provides for 64-bit transfers at a speed of 133 MHz for an amazing 1-GBps • PCI cards use 47 pins to connect • Able to work with so few pins because of hardware multiplexing • Device sends more than one signal over a single pin • PCI supports devices that use either 5 volts or 3.3 volts. • Although Intel proposed the PCI standard in 1991 • Became popularity with Windows 95 (in 1995 • Windows 95 supported a feature called Plug and Play (PnP
What is Plug ‘n Play • With Plug and Play under Microsoft Windows Server 2003 • Connect a hardware device to your system • Leave the job of configuring and starting the device to the operating system • Plug and Play in Windows Server 2003 supports a wide range of devices • In Windows Server 2003 • Plug and Play support is optimized for computers that include an Advanced Configuration and Power Interface (ACPI) BIOS • Defined by Advanced Configuration and Power Interface (ACPI) Specification • Hardware and software interface specification • Combines and enhances Plug and Play and Advanced Power Management (APM) standards • ACPI devices include low-level system devices (batteries) • On x86-based computers • Interaction between the BIOS and Plug and Play depends on whether the system BIOS or the operating system configures the hardware • Plug and Play detection runs with logon process • Relies on system firmware, hardware, device drivers, and operating system features to detect and enumerate new devices • ACPI firmware provides enhanced features, such as hardware resource sharing • When Plug and Play components are coordinated, Windows Server 2003 can detect new devices, allocate system resources, and install or request drivers with minimal user intervention.
HyperTransport • A standard proposed by Advanced Micro Devices, Inc. • Touted by AMD as natural progression from PCI. • For each session between nodes, it provides two point-to-point links • Each link can be anywhere from 2 bits to 32 bits wide • Supports maximum transfer rate of 6.4 GB per second • Designed specifically for connecting internal computer components to each other • Not designed for connecting external devices • Development of bridge chips will enable PCI devices to access the HyperTransport bus
The Windows Registry • Every operating system and application needs a place to store configuration settings and user preferences • MS-DOS uses CONFIG.SYS • DOS programs had to make their own arrangements for storing user settings • Windows originally used INI files • Read and written using special routines available to Windows programs • Windows had one configuration file, SYSTEM.INI • Used for all the internal settings • Plus another, WIN.INI, for user preferences • Each application had an INI file • INI files were slow to access and limited to 64Kb • Unsuited for the 32-bit versions of Windows • So for Windows NT and Windows 95 Microsoft introduced the Registry • A database for storing and accessing configuration data • Organized for fast and efficient access • Data is stored in a hierarchical manner like the folders on a hard disk • Registry data that is currently in use is cached to provide better performance • http://www.tech-pro.net/intro_reg.html
Numbers, Computer Style 1 0 1 0 0 1 1 0 1 0 | - | - - | | - | - x o x o o x x o x o y n y n n y y n y n • 000, 001, (rightmost digit starts over, and next digit is incremented) • 010, 011, (rightmost two digits start over, and next digit is incremented) • 100, 101, ...
Binary Arithmetic • Addition • half adder, which adds two bits together, producing sum and carry bits • The simplest arithmetic operation in binary is addition. Adding two single-digit binary numbers is relatively simple: • 0 + 0 = 0 • 0 + 1 = 1 • 1 + 0 = 1 • 1 + 1 = 10 (carry:1) • Multiple bits • 1 1 1 1 1 (carry) • 0 1 1 0 1 • + 1 0 1 1 1 • ------------- • 1 0 0 1 0 0 • http://en.wikipedia.org/wiki/Binary_numeral_system#Binary_simplified
Transistor • Switch: On or Off • Record and Manipulate Numbers (base 2) • Transistor Circuits • Logic Gates • Half-Adders • Full Adders
How does a Transistor Work Junction Transistor
How does a Transistor Work Field Effect Transistor http://tech-www.informatik.uni-hamburg.de/applets/cmos/cmosdemo.html
Homework 3 Prepare a memory map for a PC with • 1 MByte RAM • 8 PCI devices • Each PCI device requires 8 memory locations