Lesson 4 Connector Components

Serial and Parallel Ports All peripheral devices that connect to the computer use connectors on the back of the computer known as ports. A serial port can be used to connect devices that use a serial interface such as a modem, scanner, mouse, etc. A parallel port is a socket on the computer that is used to connect a printer or other peripheral device such as a portable hard disk, tape backup, scanner, or a CD- ROM.

PS/2 Ports/ 6-pin Mini DIN, 5- pin DIN PS/2 keyboard or PS/2 mouse ports are used to connect the PC to its keyboard and mouse.

Universal Serial Bus (USB) and FireWire The Universal Serial Bus (USB) is an external port and allows user to connect up to 127 external PC peripherals, including USB keyboards, mice, printers, modems, scanners, and external disk drives. FireWire, also known as i.LINK or IEEE 1394 is a high-speed, platform- independent communication bus that interconnects digital devices such as digital video cameras, printers, scanners, digital cameras, and hard drives.

IDE, EIDE, Ultra, and SCSI Controllers The internal hard drive is connected to a disk controller with a cable. The hard drive and other devices can use one of two types of interface controllers to work with the computer. These include the Enhanced Integrated Drive Electronics (EIDE), and Small Computer System Interface (SCSI, pronounced "scuzzy") connections.

IDE, EIDE, Ultra, and SCSI Controllers (cont.) Integrated Drive Electronics (IDE) is a type of hardware interface widely used to connect hard disks, CD-ROMs, and tape drives to a PC. 20 GB IDE hard disks have become entry level. The IDE interface is officially known as the AT Attachment (ATA) specification. Enhanced IDE (EIDE) or ATA-2 disk drives is the "new and improved" IDE. The EIDE interface can handle up to 8.4 GB or more. Ultra ATA disk drives are typically much faster than the older ATA and ATA-2 disk drives. Typical Ultra drive sizes can go up to 50 GB or more.

IDE, EIDE, Ultra, and SCSI Controllers (cont.) SCSI devices have the controlling electronics on each of the drives. However, SCSI is a much more advanced interface controller than ATA-2/EIDE. It is ideal for high- end computers, including network servers. SCSI devices are typically connected in a series, forming a chain that is commonly referred to as a daisy chain. There are three types of SCSI termination : 1.Passive 2.Active 3.Forced Perfection

SCSI Disk Types Three major versions of the SCSI standard are currently on the market, SCSI-1, SCSI-2, and SCSI-3. To help identify the signaling system used by SCSI devices (controllers and drives), a system of symbols has been devised to identify the different signaling systems.

SCSI Disk Types (cont.) SCSI-1, was used by many Apple computers in the early 1980s. By today’s standards it was rather slow. SCSI-2 uses two different signaling systems, known as single-ended interface and differential interface. The two signaling systems are incompatible and cannot be mixed on the same SCSI bus. This figure shows an example of a 50-pin, 68-pin, and 80-pin (SCA) connector. SCSI-3 is the latest standard of the SCSI family. It combines all the best features of the previous SCSI standards.

Storage Components

Floppy Drives A Floppy Disk Drive (FDD) magnetically reads and writes information onto floppy diskettes, which are a form of removable storage media. The main drawback to the floppy diskette is that it only holds 1.44 MB of information, although most PCs still have a floppy drive.

The Hard Drive The HDD has a much larger storage capacity than the floppy for long- term storage. It stores programs and files, as well as the operating system. Typically, the HDD is an internal drive that cannot be removed from the computer.

The Hard Drive (cont.) Hard Drive Components include: disk platters, read/write heads, head actuator assembly, spindle motor, logic/circuit board, bezel/faceplate, configuration jumpers, and interface connectors.

The Hard Drive (cont.) Disk platters are the actual media on which data is stored in the hard disk drive. A hard disk drive typically has two to ten platters. They are usually either 2 ½” or 3 ½” in diameter and are typically constructed of aluminum or a glass-ceramic composite material. Platters are stacked with spaces between them on a hub that holds them in position, separate from one another. The hub is also called the spindle.

The Hard Drive (cont.) The hard disk drive functions in much the same way as a floppy disk drive. The disk platters spin at a high speed while the drive heads access the media to conduct read or write operations. Personal computers have at least one HDD installed inside the system unit. If more storage capacity is needed, another HDD can usually be added. The capacity of the HDD is a measure of how much information it can store.

CD-ROMs A CD-ROM drive is a secondary storage device that reads information stored on a compact disc. The CD-ROM is an optical media. They are used for installing programs, running applications that install some of the files to the hard drive, and executing the program by transferring the data from the CD-ROM to memory while the program is running The major components within a CD-ROM drive are the optical head assembly, head actuator mechanism, spindle motor, loading mechanism, connectors and jumpers, and logic board.

CD-ROMs (cont.) Data is stored in the form of indentations and bumps on the reflective surface of every CD- ROM disk. The indentations are called pits, and the bumps are called lands. The most important specification for a CD-ROM drive is its speed, or how fast the disc will spin. The faster the disc spins, the faster the data can be transferred to the computer’s memory. Two other important specifications to consider are the access time and data transfer rate.

DVD - DVDRW The DVD looks like a CD, but the storage capacity is significantly higher. For this reason, many software manufacturers are starting to put programs, manuals, and other documentation on one DVD instead of multiple CDs. Recordable DVD drives will become standard on computer systems just like the CD drive did.

Backup Hardware Tape drives are most commonly used as the device for data backup on a network server disk drive. There are a variety of tape devices that use different tape formats for storing data. New USB storage devices can easily save and access 16MB, 32MB, 64MB, 128MB, 256MB, 512MB and 1GB.

Network Components

Modems A modem is the primary way to connect to the Internet with Windows 9x through a dialup networking connection. A modem is a device that converts the digital data used by computers into analog signals that is suitable for transmission over a telephone line, and converts the analog signals back to a digital signal at the destination.

Network Interface Card (NIC) A Network Interface Card (NIC), is used to connect a local computer to a group of other computers so they can share data and resources in a networked environment. All network interface cards are designed to use Ethernet, Token Ring, or another similar protocol.

Network Interface Card (NIC) cont. NICs come in form of expansion cards (PCI or ISA) that can be installed in one of the computers expansion slots. The network cable plugs to the computer through the adapter card or NIC. This is possible due to a connector type known as the RJ-45 connector it has 8 wires inside.

System Resources

What are System Resources? System resources are shared between the different hardware components or devices of the computer system that need to communicate with CPU. The CPU is a complete computation engine that is fabricated on a single chip. It not only controls the functions of the computer, but also handles requests from many input and output devices. The CPU is only capable of handling one request at a time.

Interrupt Requests (IRQ's) Various hardware devices may want to tell the CPU that they have some information available that is ready for transfer. The devices indicate this by making an interrupt request, or IRQ. It is a general rule that IRQ’s cannot be shared. A device's IRQ will cause the operating system to stop momentarily as it asks the CPU to service its request.

Direct Memory Access (DMA) Direct Memory Access (DMA) channels allow devices to bypass the processor and directly access the computer memory. DMA channels are typically used by high-speed communication devices for transferring large amounts of data at high speeds. Examples include sound cards, some network cards, some SCSI cards, some disk drives, and some tape backup drives.

Input/Output (I/O) Addresses An I/O port number is a memory address where data is temporarily stored as it moves in and out of the devices. The I/O address is very similar to a post office box. As mail comes in, it is stored temporarily in a post office box. No two boxes can have the same number or the mail can end up in the wrong box. No two devices can have the same I/O address.

Portable Devices

Notebook Computers Notebook computers incorporate the system unit, input unit, and output unit into a single, lightweight package, that can be carried around by the user. They are also called portables, laptop computers, palmtops, or personal digital assistant (PDA), depending on their size and what they can do.

Portable Hardware Portables are built with the intention of being lightweight and fitting within a certain size or form factor. Portable devices include batteries, hard drives, PCMCIA Cards, and memory. Originally, portables used Nickel Cadmium (Ni-Cad) batteries and were in an external battery pack that would attach to the portable device.

Portable Hardware (cont.) More recently, Nickel Metal- Hydride (NiMH) and Lithium- Ion batteries have been used in portable devices. These batteries usually last for a little over two hours, depending on their size and the power consumption by the device. Hard drives have been developed to be smaller and use less power to accommodate size and power limitations.

PCMCIA Cards The Personal Computer Memory Card International Association (PCMCIA) card, is a special expansion card type designed primarily to accommodate the needs of the portable computer market. There are three types of PCMCIA slots and cards: 1.Type I cards are 3.3mm thick and used as memory expansion units 2.Type II cards are 5mm thick and are used for any expansion device except hard drives. 3.Type III cards are 10.5mm thick and designed to be used solely for hard drives.

Portable Computer Displays Notebook and laptop computers use non-CRT type displays, also referred to as flat panel displays. Two examples of such displays are Liquid Crystal Display (LCD) and gas-plasma panels. –They are much lighter and more compact than CRT monitors. –They require much less electrical energy to operate. –Both types of display units can be operated from batteries

Docking Station/Port Replicator A docking station is a device that can be used to allow a portable PC to use the normal hardware devices associated with desktop computers. A port replicator is similar to a docking station. It connects multiple peripherals to a notebook but it does not contain any slots for expansion, speakers or peripherals. Docking Station Port Replicator

Upgrading and Troubleshooting Laptop Computers Use the system tools on a regular basis to keep the system running smoothly. Overheating can cause the system to slow down and malfunction. Keeping the notebook cooler can be as simple as raising the notebook slightly to allow air to circulate under the computer. Notebook cooler pads can be purchased that utilize fans powered by the USB port help keep the notebook cool.

Infrared Device Infrared technology, also known as Infrared Radiation (IR) is used for wireless transmission between computer devices and in remote controls for television and stereo systems. To successfully link two devices, there must be a transmitter and receiver with an unobstructed line of sight between the devices.

Wireless Access Points Radio signals are used in wireless networking technologies to enable computers to broadcast their information to one another using. A wireless access point is utilized so that computers in a client/server network communicate.