In the ever-evolving landscape of computer technology, the allocation of resources to various devices is a critical aspect that ensures smooth operation and optimal performance. The concept of Plug and Play (PnP) has revolutionized how devices communicate with the central processing unit, streamlining the process and eliminating the need for manual configuration. This article delves into the intricacies of resource allocation, the historical challenges it presented, and how PnP has addressed these issues, providing a seamless user experience.
In the early days of personal computing, adding new hardware to a system was a task that often required technical expertise. Each device, from keyboards to modems, needed specific resources such as Interrupt Request (IRQ) lines, memory addresses, and Direct Memory Access (DMA) channels to function correctly. IRQ lines, for instance, are crucial as they signal the processor when a device requires attention. For example, every keystroke on a keyboard sends an IRQ to alert the processor.
The system bus, a vital structure on the motherboard, facilitates communication between the processor, chipset, memory, and expansion slot devices. Initially, PCs utilized the Industry Standard Architecture (ISA) bus, which required manual setting of IRQs and other resources via jumpers or DIP switches on expansion cards. ISA devices could not share resources, meaning each needed its unique IRQ.
A typical PC only had 16 IRQs, which quickly became a limiting factor as more devices were added to systems. Standard devices like keyboards, mice, and drives had fixed resource assignments, as shown in the table below:
| IRQ | Device | |-----|--------------------| | 0 | System Timer | | 1 | Keyboard | | 2 | IRQ Controller 2 | | 3 | COM2 | | 4 | COM1 | | 5 | LPT2 | | 6 | Floppy Drive | | 7 | LPT1 | | 8 | Real-Time Clock | | 9 | ACPI | | 10 | Unallocated | | 11 | IRQ Holder | | 12 | Mouse | | 13 | Math Coprocessor | | 14 | Primary IDE | | 15 | Secondary IDE |
In 1993, Microsoft and Intel introduced Plug and Play technology to overcome the limitations of manual resource allocation. Central to PnP is the Peripheral Component Interconnect (PCI) bus, which, along with PnP-compliant BIOS, operating systems, and hardware devices, automates the configuration process.
The Advanced Configuration and Power Interface (ACPI) is a component of modern operating systems like Windows 2000/XP that manages PnP. ACPI enables power management by controlling device states such as Standby, Suspend, or Off and dynamically handles events like USB device connections or disconnections.
During system boot-up, the BIOS creates a table of used IRQs by legacy ISA devices and assigns the remaining ones to the PCI bus controller. The controller then manages the PCI bus and expansion slots, assigning resources based on device requests.
PCI steering is a feature that allows multiple devices to share the same IRQ, known as the "IRQ Holder" for PCI steering. This is managed by the PCI controller's interrupt systems, labeled A, B, C, D, etc., to differentiate from numbered system IRQs. Each PCI expansion slot is assigned one interrupt.
To view the assigned IRQ for PCI steering, users can access the "System" utility in the Control Panel, navigate to the "Hardware" tab, and click on "Device Manager." From there, selecting "Resources by type" and expanding the "Interrupt request (IRQ)" branch will display the information.
It's important to note that Windows 2000 uses IRQ 9 for PCI Steering, so devices should not be manually set to this IRQ.
Plug and Play resource allocation has simplified the once complex process of configuring hardware devices. The intricate interplay between a computer's BIOS, chipset, PCI bus, operating system, and PnP devices has been streamlined, allowing for a more user-friendly and efficient computing experience.
For further insights into maintaining your computer and leveraging it for web design and online income, visit Bucaro TecHelp. To stay updated with the latest tips and tricks, consider subscribing to the Bucaro TecHelp Newsletter.
Resource allocation in modern computing has come a long way, with Plug and Play technology at the forefront of this transformation. The seamless integration and management of hardware resources have paved the way for more accessible and powerful computing solutions.
Success at Work: Techniques : Taking Initiative
... is granted for the below article to ... ... use for ezine, ... ... as free bonus or part of
Turn Worm Poop into Cash
Two University students, Tom Szaky and Jon Beyer, enteredtheir "Worm Project" into a business plan contest atPrinceton. The project involved taking organic garbage fromthe dining halls at Princeton University and feeding it toworms. The worms processed the garbage into organicfertilizer for flowers, house plants, and vegetables.
Coffee : Poison or Health Elixir?
Computers are very complicated, so computer professionalsneed to keep their brain synapses firing rapidly. Toaccomplish this, many computer professionals consume largeamounts of coffee. Studies keep coming out that provecoffee is dangerous to our health. Other studies provethose findings to be false. Is coffee bad for us or not?
