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Unformatted text preview: and “by 8” is the correct
pronunciation. You’ll of course hear it spoken as both “by 8” and “8 ex” for
the next few years until the technology has become a household term. ch08.indd 298 12/14/09 2:49:21 PM All-In-One / CompTIA Network+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 8
All-In-One Chapter 8: Expansion Bus 299 Figure 8-12
PCIe ×16 slot
(black) with PCI
slots (white) The bandwidth generated by a ×16 slot is far more than anything other than a video
card would need, so most PCIe motherboards also contain slots with fewer lanes. Currently ×1 and ×4 are the most common general-purpose PCIe slots, but PCIe is still
pretty newso expect things to change as PCIe matures (see Figure 8-13). Figure 8-13
PCIe ×1 slots ch08.indd 299 12/14/09 2:49:22 PM All-In-One / CompTIA Network+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 8 CompTIA A+Certification All-in-One Exam Guide 300 System Resources
All devices on your computer, including your expansion cards, need to communicate
with the CPU. Unfortunately, just using the word communication is too simplistic, because communication between the CPU and devices isn’t like a human conversation.
In the PC, only the CPU “talks” in the form of BIOS or driver commandsdevices only
react to the CPU’s commands. You can divide communication into four aspects called
system resources: I/O addresses, IRQs, DMA channels, and memory addresses.
Not all devices use all four system resources. All devices use I/O addressing and most
use IRQs, but very few use DMA or memory. System resources are not new; they’ve been
with PCs since the first IBM PC.
New devices must have their system resources configured. Configuration happens
more or less automatically now through the plug and play process, but in the old days,
configuration was handled through a painstaking manual process. (You kids don’t
know how good you have it. Oops! SorryOld Man Voice.) Even though system resources are now automated, you still might run into them in a few places on a modern...
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