1. Plug ‘n Play, Semiconductors, Bits and Transistors
Dr. Harold D. Camp IT
8 February 2007

2. Components of a Normal PC

3. Hardware Interrupts

4. 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

5. 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

6. 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

7. 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

8. 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

9. Variety of Busses Bus Type Bus Width Bus Speed MB/sec
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
Bus Type
Bus Width
Bus Speed
MB/sec
ISA
16 bits
8 MHz
16 MBps
EISA
32 bits
32 MBps
VL-bus
25 MHz
100 MBps
33 MHz
132 MBps
PCI
64 bits
264 MBps
66 MHz
512 MBps
133 MHz
1 GBps
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

10. Backside Bus The backside bus Backside buses evolved over years
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

11. 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

12. 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.

13. Plug ‘n Play Architecture

14. Plug ‘n Play Components

15. Plug ‘n Play Device States

16. Plug ‘n Play Rules Devices on These Buses or Connectors
Can Be Added to or Removed from a Running System?
System Must be Turned Off Before Device is Added to or Removed from System?
USB, IEEE 1394, PC Card devices, CardBus devices
Yes. Remove hardware by using the Safely Remove Hardware application if it appears in the notification area.
No.
PCI, ISA, EISA
Yes.
Docking station
Varies among computer manufacturers; most support docking and undocking while the computer is running.

17. 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

18. 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

19. Numbers, Computer Style
| - | - - | | - | -
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, ...

20. 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
(carry)

21. Transistor Switch: On or Off Record and Manipulate Numbers (base 2)
Transistor Circuits
Logic Gates
Half-Adders
Full Adders

22. How does a Transistor Work
Junction
Transistor

23. How does a Transistor Work
Field
Effect
Transistor

24. Homework 3 Prepare a memory map for a PC with 1 MByte RAM
8 PCI devices
Each PCI device requires 8 memory locations