System Resources INFO1119 (Fall 2012)

System Resources Used to communicate…  Hardware with Software or Software with Hardware 4 Types of System Resources (Interrupt Request) (Direct Memory Access) INFO1119 (Fall 2012)

System Bus Components Made up of 3 Components  Data bus, Address bus, and Control bus INFO1119 (Fall 2012)

System Resources and the Bus System resources require specific lines on the bus: Data uses the data bus Memory addresses and I/O addresses use the address bus IRQs and DMA channels are controlled by the control bus INFO1119 (Fall 2012)

Interrupt Request Number (IRQ) Used by hardware to tell the CPU “I need attention”  Hardware Interrupt IRQs have a designated line on the bus for each IRQ that is available. Some IRQs are either pre-assigned or used by standard devices. INFO1119 (Fall 2012)

Interrupt Controllers The original IBM PC used the fanciest interrupt controller chip they could get at the time, the 8259. Unfortunately, it only could handle eight (8) interrupts. With the IBM AT, they chained them together, placing another 8259 onto the IRQ2 of the first 8259 This gave a total of 15 interrupts INFO1119 (Fall 2012)

Second Interrupt Controller Chip INFO1119 (Fall 2012)

IRQ Priority The lower the IRQ number the higher the priority Because the second controller is wired to IRQ 2, the IRQ priority order is as follows: 1 8, 9, 10, 11, 12, 13, 14, 15 3 4 5 6 7 INFO1119 (Fall 2012)

An Expansion Slot with Bus Lines Original 8 bit IBM PC ISA expansion slot SD# = Data bus line. SA# = Address bus line. IRQ# = IRQ line. DRQ# = DMA line. CLK = System clock signal. #DC = Power line. Expanded (16 bit) ISA expansion slot of the IBM AT (which is what you have now) INFO1119 (Fall 2012)

Device Manager From the Control Panel/System, load the Device Manager From the “View” menu select “Resources by type” INFO1119 (Fall 2012)

IRQ Assignments INFO1119 (Fall 2012)

Devices Without IRQs Some devices don’t require IRQs Software that runs continuously has the CPU check the device for service. Called polling. INFO1119 (Fall 2012)

Memory Address and I/O ports Since the CPU is built to access memory (RAM), connected system devices can: “map” to memory in the computer This is where what seems like RAM to the computer is actually locations in the device They behave like memory (RAM) to the CPU Use I/O ports Not like networking ports Accessed like memory locations, but with different instructions in the CPU INFO1119 (Fall 2012) 13

Memory Address Assignments INFO1119 (Fall 2012)

I/O Addresses INFO1119 (Fall 2012)

IRQs and I/O Addresses The table lists standard IRQs and I/O addresses for devices on a computer system. INFO1119 (Fall 2012)

How the Keyboard Uses its IRQ and I/O Address You press a key on the keyboard The keyboard controller sends its assigned IRQ to the CPU, thus saying, “I need attention.” The CPU sees the IRQ and turns its attention to servicing it The CPU uses the IRQ to point to a row in the I/O address table assigned to that IRQ to transfer data to / from the device. Using that address it will find the key stroke data. From the memory address table, the CPU locates the addresses in which the instructions to service the keyboard are stored. INFO1119 (Fall 2012)

DMA Channels Direct Memory Accessing is where information is copied from one location to another (usually to or from main memory) without the use of the CPU In the original PC and AT, the CPU simply wasn’t fast enough to even copy data from a floppy or hard drive into main memory More than one transfer can be going on at any one time, each transfer takes place through a “channel” (which just prevents conflicts – it isn’t actually separate wires or anything) Concept is still used widely today (why waste CPU cycles on something simple and boring like memory transfers?) Your PC, PS3, Xbox, etc. In the PC, used mainly by older devices, like floppy drives, tape drives, etc. INFO1119 (Fall 2012)

Updating Device Drivers INFO1119 (Fall 2012)

Updating Device Drivers As part of this driver update process, you can update drivers from a hardware installation disk, a downloaded installer or from Windows Update Open the Device Manager from the Control Panel INFO1119 (Fall 2012)

Updating Device Drivers Locate the hardware device where you want to update the drivers After finding the hardware you're updating drivers for, right click on the hardware's name or icon and choose “Properties.” In this Properties window, click the “Driver” tab Click the “Update Driver” button to start the Update Driver software wizard On the How do you want to search for driver software? window, click on “Browse my computer for driver software” INFO1119 (Fall 2012) © 2011, Fanshawe College 21

Updating Device Drivers con’t…. Locate the hardware device where you want to update the drivers In the next window labelled Browse for driver software on your computer, click on “Let me pick from a list of device drivers on my computer,” located at the bottom of the window Click the “Have Disk...” button located under the text box Click the “Browse...” button on the Install From Disk dialog box that appeared INFO1119 (Fall 2012) © 2011, Fanshawe College

Updating Device Drivers, con’t…. Navigate to the folders where the drivers are located Click any INF file that displays in the file list and click the “Open” button (INF files are the only file type accepted by the Device Manager) Click the “OK” button back on the Install From Disk dialog box Choose the newly added hardware in the text box and then click the “Next >” button The Windows 7 Update Driver Software wizard will now use the instructions provided in the INF file to install the updated drivers for your hardware INFO1119 (Fall 2012) © 2011, Fanshawe College

Updating Device Drivers, con’t…. Updating Device Drivers Navigate to the folders where the drivers are located Follow any additional instructions on screen to complete the driver update Note: You may be asked to reboot the computer after the driver installation is completed INFO1119 (Fall 2012) © 2011, Fanshawe College

Rolling Back Device Drivers If an updated driver fails, you may need to roll back the driver to the previous version Right-click the problem device and open the “Properties” window, then select the “Drivers” tab Click the “Roll Back Driver” button INFO1119 (Fall 2012) © 2011, Fanshawe College