Expansion slots

Using the PC for control requires installation of a board into the expansion slot in the computer, or the PC can be connected to an external I/O module using a standard communication port on the PC (RS-232, RS-422, or IEEE-488). The controller card/module supports 16- or 32-bit microprocessors. Standardization and high volume in the PC market has produced a large selection of hardware and software tools for PC controllers. 

I he spine of the computer is the system board, otherwise known as the motherboard (and less commonly referred to as the planar board). This is the olive green or brown fiberglass sheet that lines the bottom of the computer. It is the most important component in the computer because it is the component that connects all the other components of a PC together. Figure 2.2 shows a typical PC system board, as seen from above. It is on this sheet that all other components are attached. On the system board you will find the CPU, underlying circuitry, expansion slots, video components, RAM slots, and a variety of other chips. 

Nonintegrated system boards have each major assembly installed in the computer as expansion cards. The major assemblies we re talking about here are items like the video circuitry, disk controllers, and accessories. Nonintegrated boards can be easily identified because each expansion slot is usually occupied by one of the components we just mentioned. 

Nonintegrated system boards are also classified by their form factor (design) AT, ATX, or NLX (and variants of these). The AT system boards are the same as the motherboards found in the original IBM AT. The processor, memory, and expansion slots are all in line with each other. Because of advances in technology, the same number of components that were on the original AT motherboard (now called a full AT board) were later compressed into a smaller area. This configuration is known as the baby AT configuration. 

A fairly new motherboard form factor that has been gaining popularity in the last couple of years is NLX. This form factor is used in low profile case types. What makes them unique is that the expansion slots are placed sideways on a special riser card (as shown in Figure 2.3) to optimally use the space. 

Expansion slots Memory slots Processor slots or sockets Power connectors On-board disk drive connectors Keyboard connector Peripheral port connectors BIOS chip CMOS battery Jumpers and DIP switches... 

The most visible part of any motherboard is the expansion slots. These look like small plastic slots , usually anywhere from 3" to 11" long and approximately Vi" wide. As their name suggests, they are used to install various devices in the computer to expand its capabilities. Some expansion devices that might be installed in these slots include video, network, sound, and disk interface cards. 

If you look at the motherboard in your computer, you will more than likely see one of three main types of expansion slots ... 

Each type differs in its appearance and function, which you learn more about in Chapter 5, PC Bus Architectures. In this chapter we will cover how to visually identify the different expansion slots on the motherboard. 

Which motherboard form factor places expansion slots on a special riser card and is used in low profile PCs ... 

What type of expansion slot is used almost always for high-speed, 3D graphics video cards ... 

A. The spine of the computer is the system hoard, otherwise known as the motherboard. On the system hoard you will find the CPU, underlying circuitry, expansion slots, video components, RAM slots, and various other chips. 

I he expansion bus allows the computer to be expanded using a modular approach. Whenever you need to add something to the computer, you plug specially made circuit boards into the connectors (also known as expansion slots) on the expansion bus. The devices on these circuit boards are then able to communicate with the CPU and are semipermanently part of the computer. 

In the next section, we discussed the components that make up a bus. You learned about each component and how those components work together to facilitate communication between the expansion card and the rest of the circuitry in the computer. Some of these components include the expansion slot itself, the various lines between the slot and the processor, and the bus controller. You also learned how different busses use different circuitry. 

EISA Configuration Utility (EISA Config) VESA Local Bus slot expansion slots... 

Now that your sound card is configured, you can finally mount the device into the computer. Mounting a device usually means attaching it to the computer s case with some kind of fastener and attaching the device to an interface. In this case, it means installing an expansion card into an expansion slot and securing it with a screw. 

Next, align the connector on the bottom of the card with the connector on the motherboard and insert the card into its connector. You should feel a slight amount of resistance. Push the card firmly into place with an even pressure on the front and back of the card. Stop pushing when all of the card s connectors are making contact with the fingers in the expansion slot. 

Another example of a hardware resource is a resource discovery expansion-card. These cards, when installed into any expansion slot, will tell you what resources are being used in the computer and will indicate any possible conflicts. Several companies make these cards. 

A. The XT featured a 10MB hard drive, a serial interface, and three additional expansion slots. It also had 128KB of RAM and a 360KB floppy drive. 

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