1. A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting
System Resources
Tool used by either hardware or software to communicate with the other
Four types of system resources
Interrupt request numbers (IRQs)
Memory addresses
I/O addresses
Direct memory access (DMA) channels
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

2. System Resources (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

3. System Resources (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

4. Interrupt Request Number (IRQ)
Method allowing a hardware device to signal the CPU for attention
A hardware interrupt
Initiated by device when it places a voltage on the designated IRQ line assigned to it
This voltage on the line serves as a signal to the CPU that the device a has request that need processing
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

5. Interrupt Request Number (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

6. Interrupt Request Number (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

7. Interrupt Request Number (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

8. Interrupt Request Number (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

9. A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting
Memory Addresses
OS relates to memory as a long list of cells to hold data and instructions
Each cell is assigned a number
Begins with zero
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

10. Memory Addresses (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

11. A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting
I/O Addresses
CPU “knows” a hardware device as group of I/O addresses.
Each device needs a range of I/O addresses so that the CPU can communicate more than one type of command to it
IBM set many address assignments in ’70s for hard drive, floppy drive, keyboard
Memorize the first I/O addresses in the I/O address range for significant devices
Plug and play devices can use any I/O address or IRQ assigned during boot
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

12. I/O Addresses (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

13. A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting
DMA Channels
Shortcut allowing an I/O device to send data directly to memory, bypassing CPU
Chip on motherboard contains DMA logic and manages the process
Early computers used channels 0, 1, 2, 3
Channels 5, 6, and 7 were added and 4 used to cascade to lower DMA
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

14. DMA Channels (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

15. OS Tools to Examine a System
Device Manager
Tool for information about devices
System Information
Information useful for troubleshooting
Microsoft Diagnostic Utility (MSD)
Useful for viewing information about the system
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

16. OS Tools to Examine a System (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

17. OS Tools to Examine a System (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting

18. OS Tools to Examine a System (continued)
A+ Guide to Hardware: Managing, Maintaining, and Troubleshooting