Chapter 1: Hardware

E-mail this to a friend

Newsletters: Sign-Up & Save! Receive Special Offers, Free Chapters, Articles Reference Guide Updates, and plug into the pulse of what’s happening in your corner of the industry by subscribing to InformIT newsletters! FREE coupon after sign-up!

Try Safari Books Online NOW! Access the largest fully searchable e-reference library for programmers and IT professionals!

 Hardware is one of six domains in the CompTIA A+ Exams. It is a major piece of both exams. Hardware accounts for 27 percent of the 220-701 Essentials Exam and 38 percent of the 220-702 Practical Applications Exam.

CPUs

The Central Processing Unit (CPU) is the main processing unit of the personal computer (PC). It has an integral relationship with the motherboard and the system memory. These three devices control the data-processing aspect of the PC. Drives handle data storage, and input/output (I/O) interfaces allow human interaction, communication with peripherals, and network communication.

RISC Versus CISC

Most general purpose PCs use a complex instruction set chip (CISC). Many dedicated computers used in data collection, sensors, routers, and graphics processors are reduced instruction set chips (RISC). These two types of processors can complete the same tasks, but if the computer is processing the same kind of data all the time, it is often more efficient to reduce the amount of possible instructions the CPU can execute. This makes the decision-making process simple and quick.

32-Bit Versus 64-Bit CPUs

32-bit processors are slowly being replaced by 64-bit processors as an increasing number of applications and operating systems (OS) support them. You should use a 64-bit OS and applications on a 64-bit CPU to get the full benefit of increased performance. Most 64-bit applications are backward compatible and will work on 32-bit CPUs.

Clock Rate

The actual speed of the CPU is governed by a BIOS setting called the clock rate. CPUs run in a range of speeds, not just one specific speed. Increasing the speed is called over clocking. It improves performance, but it comes at a cost. The faster the CPU runs, the hotter it gets. If it gets too hot, the BIOS shuts down the CPU. If the temperature thermocouple is not correctly reading the CPU heat, the CPU can actually melt or catch fire. More sophisticated motherboards throttle down the CPU speed in the event it gets too hot to prevent entirely shutting down the computer.

Cores and Cache

CPUs traditionally contain only one core. Some server and workstation motherboards can support multiple CPUs (multiprocessor). More commonly, you can find PCs with one CPU that includes two or four cores (dual or quad core, respectively) Multicore is not the same as multiprocessor. Multiple cores allow the PC to simultaneously process multiple tasks (threads).

Multicore CPUs still share a common front side bus, which can cause traffic bottlenecks as competing cores communicate on the main system bus. In contrast, each core has its own internal bus that allows independent access RAM.

Shared cache is another good reason for multiple cores. Cache is a temporary storage for the core so that it can “remember” the most recent processes. It is like looking up a topic in this quick reference guide as opposed to a giant 1,400 page A+ exam-preparation book.

There are three levels of cache:

• Level one cache is located on the CPU.

• Level two cache is located on the motherboard.

• Level three cache is located on removable chips on the motherboard.

CPU Interfaces and Socket Types

The motherboard supports the CPU in several ways:

• Chipsets help direct and process data and commands for the CPU.

• Sockets allow the CPU to connect to the computer.

• The motherboard provides power to the CPU.

• It measures the temperature and controls fans to cool the CPU.

• The motherboard shuts down the PC if the CPU is too hot to prevent damage.

Intel and Advanced Micro Devices (AMD) have many models and qualities of CPUs. Each model is designed to fit into a specific socket on the motherboard. Many pins connect the CPU to the motherboard. Bending (or breaking) even one pin renders the CPU inoperable. A Zero Insertion Force (ZIF) physical interface lets you set the CPU into the array, and then you actuate a lever to make actual contact. It is imperative to orient the CPU correctly. Usually, there is an obvious guide or indication, like a missing corner pin on the CPU, that aligns to a missing hole in the ZIF. Pin Grid Array (PGA) and Line Grid Array (LGA) describe the pin arrangement of the CPU interface with the motherboard. Tables 1-1 and 1-2 list processors and their associated sockets.

Table 1-1  AMD Sockets and CPUs

Table 1-2  Intel Sockets and CPUs

System Memory

There are two major types of memory: dynamic and static. Dynamic Random Access Memory (DRAM) loses information in the absence of power. Static RAM (SRAM) retains its data like a hard drive regardless of power state. In general, DRAM is used as system memory, and SRAM is used for cache and storage devices.

SDRAM is neither a contradiction in terms nor a type of hybrid RAM. It actually stands for Synchronous Dynamic RAM. Synchronous means that the data transfer is timed to the system clock. For many years, 168 pin SDRAM was the standard system memory. It has largely been replaced with Double Data Rate (DDR), DDR2, and DDR3. All these types of RAM use a common Dual Inline Memory Module (DIMM) form factor, but they all have unique form factors and are, therefore, not interchangeable.

Like most things on a PC, RAM is measured in speed. The motherboard must support the speed of the RAM, or the increased performance promised by the fast RAM will not be realized; or worse, the PC might not even Power On Self Test (POST).

Other Types of RAM

RAMBUS Inline Memory Module (RIMM) uses a proprietary 184-pin or 232-pin slot called a RIMM. This RAM, often called RDRAM, is found in some game console systems and a limited number of PCs. On such systems, empty RIMM slots must be filled with Continuity RIMM (CRIMM) modules.

Older Single Inline Memory Modules (SIMM) have 30 or 72 contacts on only one side. SIMMs must be installed in identical pairs.

Laptops use a small form factor called Small Outline DIMM (SODIMM). Many netbooks, Ultra Mobile PC (UMPC), and portable devices, such as cell phones and PDAs, use a MicroDIMM form factor. Figure 1-1 compares the relative size and form factors found in RAM.

Figure 1-1

RAM Comparison

VRAM and Virtual RAM

VRAM is video RAM for the use of the Graphic Processing Unit (GPU). VRAM does not stand for Virtual RAM. Virtual RAM is space on the HD that the RAM uses as an overflow area and as a backup copy of the contents in case of power failure.

Parity and ECC

Parity is a method of verifying data integrity. It is used when the reliability of the data is more important than the speed at which it is written or read. Parity adds a bit to each byte so that every byte is an even number. When the data is read or received, the bytes should still be even. If not, the data is corrupt. Parity is used in some network communications, hard drives, and RAM. Error correction code (ECC) detects and fixes corrupt data in RAM. Both Parity and ECC decrease efficiency, but increase reliability.

Motherboards

A motherboard connects everything. It facilitates interoperability among the trinity (CPU, RAM, and motherboard). It communicates with storage devices through SATA and PATA headers. It also allows for expansion through the use of adapter cards. Motherboards usually have integrated I/O ports to support common peripherals.

BIOS

The BIOS is stored on the CMOS chip that is on the motherboard. The BIOS handles fundamental system configuration. The CMOS chip is actually a combination of NVRAM and volatile RAM. The NVRAM allows the BIOS to be updated (flashed). If the BIOS cannot recognize a new device, updating the BIOS is a solution. A small battery maintains a charge so the settings are not lost in the RAM when the PC is off. If the date and time reset when the computer restarts, replace the battery. The BIOS allows you to do the following:

• Enable/disable integrated devices

• Order the boot sequence

• Manage drive controllers

• Adjust battery and power supply settings

Form Factors

There are a few basic form factors for motherboards. ATX is the basis of all modern motherboards. BTX is slightly bigger and is used primarily by manufacturers. ATX is often the choice of custom-built computers. There are countless motherboard sizes and capabilities. Table 1-3 outlines the common form factors.

Table 1-3  Motherboard Form Factors

Expansion Cards and Slots

Expansion cards allow the motherboard to connect and control countless devices to the PC via proxies called adapter cards. Adapter cards also share some of the processing responsibility, which lightens the load on the CPU. Table 1-4 describes the standard expansion slots.

Table 1-4  Expansion Slots

Figure 1-2 shows the relative size and form factors of the common expansion slots. You should be able to identify these during your CompTIA A+ Exams.

Figure 1-2

Expansion Slot Comparison

Adapter Cards

The expansion slots support adapter cards. Some cards control internal devices, such as hard drives, and most communicate with external devices, such as monitors, printers, network equipment, and so on. Table 1-5 focuses on the most common adapter cards.

Adapter cards have two connections: One connects to the expansion slot, and the other connects to devices. This usually involves a port or plug. Table 1-5 contains the standard ports.

Table 1-5  Adapter Cards

Daughter Boards and Riser Boards

Daughter boards and riser boards are essentially the same device. These smaller boards plug into the motherboard that expand the number of expansion slots, ports, or, in some cases, add devices. If the board is used solely to add extra PCI slots or turn the angle of adapter cards to fit into smaller cases, it is a riser. The two exceptions are Audio Modem Riser (AMR) and Communications Network Risers (CNR). They are an evolutionary missing link between true integrated devices and full-fledged expansion cards.

Storage Devices

There are many types of storage media: magnetic disk, tape, laser, and solid state flash. There are internal drives and external storage devices. Internal hard drives mount in 3.5 inch or 2.5 inch bays. Optical drives mount in 5.25 inch bays. External drives connect through many kinds of readers and ports. USB, FireWire, and eSATA are common. Card readers and optical drives support flash memory cards and optical discs.

Dynamic and Solid State Drives

Dynamic state drives (DSD) use armatures that move read/write heads over spinning magnetic platters. The disk is organized into tracks (rings) and sectors (radial lines).

Solid state drives (SSD) contain chips that contain NVRAM. This is often called flash memory. The name came from flashing the CMOS Chip’s NVRAM to update the BIOS. Solid state HDs, flash, NVRAM, Thumb drives, Jump drives, and USB drives are essentially the same type of device.

Optical Drives CD/DVD/RW/Blu-Ray

Optical disks organize data in a long outward spiral. Optical drives use a laser to shine on the surface of the spinning disk. The laser reflects off the surface and hits a sensor or hits a bump and bounces somewhere else. From the sensor’s perspective, it “sees” a binary pattern. Table 1-6 compares the different kinds of optical drives.

Table 1-6  Optical Drives

Installing SATA, PATA, and SCSI Drives

Serial ATA drives are fast becoming the industry standard. They are hot swappable, and the header must be enabled in the BIOS. eSATA is simply an extension cord that puts a SATA header on the outside of the case for external SATA HDs. To install a SATA drive, simply plug it into a SATA or eSATA header and make sure that header is enabled in the BIOS.

Parallel ATA (PATA) is more complicated. The BIOS manages PATA configurations. There are typically two PATA channels: primary and secondary. Each channel can contain two drives: master and slave. The master/slave or cable select (CS) settings must also be set by jumpers on the drives. The cable select allows the drive at the far end of the cable to be master. Note that, in some cases, in both 80 and 40 pin PATA environments, the CS simply does not work. Simply set the jumpers to reflect the master on the end and slave in the middle. If you still have no luck, consider an HDD failure or PATA controller failure. Put together, any given PATA drive (HDD or optical) has one of the assignments shown in Table 1-7.

Table 1-7  Typical PATA Settings

SCSI is actually a small network of devices controlled by an SCSI controller. The controller is a card that plugs into a PCI or PCI-e slot and has one of many different kinds of SCSI style ports on the outside and several internal ribbon cable connections. One way to spot an SCSI cable is its width. It will always be the widest (most pins) in the PC, markedly more than PATA 40, FDD 34, and SATA 7. (SATA sometimes has 15 pins if it provides its own power.) Another way SCSI cables differ from other cables is that they have nine connectors to support the card and eight devices. An SCSI array requires unique IDs, created using a binary code: 3 bits for SCSI1 and 4 bits for Wide SCSI. This code is set by jumper, dip switch, push button switch, or can be configured with a separate SCSI BIOS. SCSI arrays also need a common medium (SCSI cable), termination at each, and a controller card.

Just like on a network, every device needs a unique ID number. SCSI “chains” need terminators at each end to absorb the signal. In place of terminators, it is common to install a termination enabled device at each end to serve as both HDD and terminator.

RAID

Redundant Array of Inexpensive (or Independent) Disks (RAID) has several defined levels, but the most common are 0, 1, and 5. RAID 0 writes the data across two drives. This increases speed, but does not provide any protection. Striping is the technique used to write the data across multiple disks. Raid 1 (mirroring) simply copies one HDD to the other.

In RAID 5, there are at least three HDDs. RAID 5 also strips the data so that it has some benefit of increased performance and spreads out the data in case of failure. RAID 5 is the most common implementation. Hybrids such as RAID 1+0 and 0+1 exist, and they require at least four disks, because they are either two striped disks that are mirrors to two others, 0+1, or they are two mirrored disks striped to two others, 1+0.

Table 1-8 compares SATA, PATA, and SCSI drives.

Table 1-8  Drive Interfaces

Media Cards

There is a wide variety of SSD storage cards used primarily in phones, cameras and other portable devices. PCs use card readers to interface with this type of storage media. The secure digital card (SDcard) is a common media card. One particular note about SDcards is they have a switch that makes the card read/write or read-only. Floppy disks also have this feature. SDcards are small and hold a considerable amount of data that is comparable to small HDs.

Other Storage Devices

Floppy Disk Drives (FDD) mount to a 3.5-inch bay and read a removable media, such as the SDcard. Unlike the small hi-capacity SDcard, the floppy disk is about 3 inches square and holds only 1.44 MB.

USB flash drives are essentially a smaller (both in size and capacity) external SSD that connects through a USB port. These are easily lost and should not be used to store secure information.

Network attached storage (NAS) is an HD with a NIC interface. It often uses a web interface and controls user access. These devices are a small office, home office (SOHO) version of proper file servers found in corporate environments. A mapped drive is an icon that is a shortcut to an NAS or file server.

Cooling

There are several methods of removing heat from a PC. The most common solution is a heat fan that blows air over a heat sink that is held firmly to the CPU. Heat sinks use parallel fins to increase the surface area like motorcycle and lawn mower engines. Many GPUs have their own cooling fan and heat sink assembly.

A thermal compound is used between the heat sink and the CPU. Note: The thermal compound is poisonous and toxic to humans. Use care when applying or removing thermal compound. Dust collects on the heat sink, which decreases its efficiency. Use compressed air or a PC vacuum to remove dust.

In some exotic and gaming PCs, liquid cooling systems transfer heat from the CPU to a radiator using water and antifreeze. These work in much the same way as an automobile’s cooling system. They are somewhat less reliable, but they provide excellent heat exchange.

Power Supplies

Safety first: Do not open a power supply. It contains capacitors that hold a dangerous charge, even while unplugged. It is a field replaceable unit (FRU). In other words, if it is broken, simply replace the entire power supply. Before sending it to a recycling facility, the capacitors should be discharged by touching and connecting the phase with the ground plug and then the neutral to the ground plug with an insulated screwdriver or pliers.

Most power supplies follow a standard form factor. The myriad form factors of computers warrants an equally diverse number of power supply form factors.

Power supplies are measured in watts. The watts output should exceed the PCs power demand. There are four kinds of power connections from the power supply top to the PC. Berg and Molex are the standard small and large (respectively) connections for drives and other devices. The motherboard has a 20-pin connector and most have an additional 4-pin connector.

Power fluctuations are devastating to a PC. Table 1-9 describes five power fluctuations.

Table 1-9  Power Fluctuations

Table 1-10 describes solutions to the previous power issues.

Table 1-10  Power Protection Devices

Monitors and Display Metrics

Contrast ratio is the comparison of the brightest to the darkest color a monitor can create. The higher the ratio, the more brightness variation exists in the monitor.

Video cards have a basic resolution, usually 640×480 or 800×600, with 256 colors. If the PC boots to this reduced resolution and limited color scheme, it needs a better video driver. Table 1-11 shows the resolutions you need to know for the A+ exam.

Table 1-11  Monitor Resolutions

These are examples of 4:3 aspect ratios. Many new computers and laptops use a 16:9 aspect ratio (HDTV/widescreen). After the correct drivers are installed, an LCD screen really should be run in its native mode.

CRT

Warning: Do not open CRTs. They are field replaceable units (FRU). In other words, replace CRT. Do not fix them. They contain capacitors that can shock you long after they are unplugged. Before sending CRTs to a recycler for disposal, the capacitors should be discharged by touching and connecting the phase with the ground plug and then the neutral to the ground plug with an insulated screwdriver or pliers.

A Cathode Ray Tube (CRT) monitor has many manual adjustments that should all be set to “middle” level. A beam sweeps sideways lines down the entire length of the screen 60–100 times a second. The width and height of the picture is controlled by controls Vertical and Horizontal, respectively. Contrast and brightness should also be set for a middle setting. Contrast controls the ratio of the brightest and darkest light. Brightness controls the overall intensity of the display. They are physically measured diagonally. A 17-inch display means it is 17 inches of viewable display measured from diagonal corners. Interlacing draws the odd numbered rows of each frame, and then one-sixtieth of a second later, fills the space with the even numbered rows.

LCD

Liquid Crystal Display (LCD) is quickly replacing large, heavy CRT monitors. LCD monitors are illuminated several different ways: a flat florescent tube, a panel of LEDs, or in the case of LCD projectors, a bright bulb. LED backlighting offers more clarity, thinner, and is more rugged than the florescent.

Passive matrix LCD monitors have chips that control the vertical and horizontal sets of wires. When a pixel is charged by both chips, it turns on. Active matrix monitors act like one big integrated circuit with the crystals for transistors.

Other Display Devices

The two principal measures of projectors are resolution and lumens. A lumen is a measure of brightness. There are two competing display technologies that make projectors and, by extension, rear projection TVs/monitors work. LCD is a small high-definition LCD screen with a light shone through it, like a stained glass window. Digital Light Processing (DLP) uses an array of mirrors that reflected light either onto the screen or away, in much the same way optical drives read their media.

It is not uncommon to have multiple monitors on one PC. The most common case of this is a laptop paired with a projector. Function keys toggle among settings that mirror the display, extend the display from the main screen onto the projector, or run the projector exclusively and shut off the main screen. Workstation and gaming PCs commonly have two or more monitors usually set up as a continuation from one to the next. The display settings in the Control Panel provide more control and support for multiple monitors.

I/O Devices

Most input/output (I/O) devices connect to a PC via a USB port. Even wireless devices ultimately terminate at the PC through a USB port. All I/O devices require drivers. Drivers are instructions to teach the OS how to use and communicate with a new piece of hardware. They are normally stored on CDs that come with the device, but they can also be downloaded from the manufacturer’s website. Often, drivers are included in the OS for commonly used devices, such as mice, keyboards, USB storage, and many printers.

Mice and Keyboards

Optical mice use an LED to illuminate the area directly beneath the mouse and a motion-sensing technology to determine the direction and speed of that surface as the mouse moves. Ball mice use a ball that roles on two rollers mounted perpendicular to each other. One measures movement along the Y axis and the other on the X axis.

Speakers and Microphones

The audio port uses a “headphone jack.” The formal name for this port is a mini DIN Tip Sleeve Ring (TSR) 3.5 millimeter jack. This makes the audio port compatible with standard stereo equipment. A higher quality audio connection splits the signal into component signals. Dolby 5.1 uses five and often seven ports each to a dedicated speaker. These are analog signals, which means that the sound card is responsible for digital-to-audio conversion (DAC). Sony/Phillips Digital Interface Format (SPDIF) sends a digital signal over a fiber-optic line to the speakers where it is decoded and converted to an analog signal and, ultimately, an audible sound.

Microphones are essentially speakers in reverse. The diaphragm moves in response to sound waves. That signal is converted into a digital signal inside the sound card. Note: The pink is a microphone port, the blue color is a line in like a stereo or iPod, and the green color is audio out for speakers and headphones. These are de facto standards and are, therefore, not consistent among all manufactures.

Video Input Devices

Still image, video, and webcams work on the same basic principal. A charged coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) converts a visual input into a binary stream through an analog-to-digital conversion (ADC). A significant difference is the way in which the camera transfers that image to the PC.

With standalone video cameras (camcorders and digital cameras), video and pictures are often stored as files that are transferred to the PC, such as a USB flash drive through a USB, FireWire port, or Bluetooth connection. In streaming video environments (security cameras, TV, and movie production), the ADC can take place in the camera and stream a digital signal through a USB or FireWire port.

In many situations, the camera does not stream a digital signal. Instead, it sends an analog signal through RCA, S-video, network interfaces, or proprietary ports. In this case, the ADC takes place in a video capture card.

Once on the PC, the video must either be stored or viewed in real-time or both. Applications such as video-editing software manipulate the raw video, much like a word processor can open, edit, and save a document.

Other I/O Devices

Some devices require additional applications to work properly. Biometric devices combine an input device with an application that compares a unique pattern retina, fingerprint, palm print, and so on, to a password. That password is then used to gain access to the OS or file. Touch screens are an input device that maps the coordinates of the touch location to an application that translates that into executable commands or files. Barcode readers shine a laser on a black-and-white barcode. The laser reflects the pattern to a sensor and reads the code. That code is compared to a database and the associated item or file is accessed.

Laptop Hardware

There are a few types of laptops, each with a different philosophy. A general laptop (notebook) is a portable, battery-powered desktop. A netbook is a barebones, tough, lightweight notebook that is cheap, but has limited capabilities. An ultra mobile personal computer (UMPC) is powerful, small, and very expensive compared to traditional laptops and netbooks.

Laptop Form Factors

Most components in a laptop are specially designed to reduce weight, space, heat, and power consumption. As a result, many have unique form factors. Small Outline Dual Inline Memory Module (SODIMM) and MicroDIMM are RAM form factors used in laptops and mobile devices (smart phones), respectively. Laptop hard drives measure 2.5 inches and can either be dynamic (platters, read/write heads) or solid state (flash). Optical drives are often removable or purely external and connect through a USB port.

ACPI Power Management

Advanced Configuration Power Interface (ACPI) is found in the power management applet in the Control Panel. On a historical note: Advanced Power Management (APM) is the predecessor of ACPI and was supported in 9x, 2K, XP. Vista and Windows 7 do not support APM. ACPI is not exclusively a laptop technology, but it is designed to maximize battery life. ACPI must first be enabled in the BIOS, like an integrated device. There are six power states, as shown in Table 1-12.

Table 1-12  ACPI Power States

Batteries

Batteries are a major issue with all portable devices. Physical dimensions and connections vary widely based on the manufacturer. In addition to laptop batteries’ proprietary nature (noninterchangeable), they are also measured by the number of cells and Amps per hour (Ah). A cell is the actual electrochemical unit. Ah is a rough estimate of how many amps are delivered over time.

Over time, the electrochemical reaction happens faster and leads to the battery forming a “memory.” Periodically, technicians “exercise” some batteries to combat memory problems. To exercise a lead-acid, alkaline, and Ni-Cad, drain the electricity completely and then charge it slightly above normal several times in a row. Ni-Mh, Li-Ion, and Li-Po naturally do not have memory problems. All batteries from giant UPS to BIOS must be disposed of according to local government regulations. Table 1-13 describes the characteristics of different battery types.

Table 1-13  Batteries

Laptop I/O Devices

Laptops and portable devices have many unusual I/O methods. Touch pads and touch screens are essentially the same device. A touch screen is clear and sits in front of a monitor. A digitizer is a higher resolution touch screen. Often, it uses a stylus, which is a sharp stick that allows users to contact the screen with precision. This should not be confused with a point stick, which is a pointing device that functions like a small “joystick” game controller in the middle of the keyboard that moves the arrow on the screen. Function keys control many aspects, such as switching between external monitor modes, ten-key pads, and screen settings.

Laptop Expansion

Mini-PCI expansion allows for some additional functionality of laptops. Personal Computer Memory Card International Association (PCMCIA) cards can be used if the laptop is designed for them. Express cards look and act much like PCMCIA cards, but they are slightly narrower. Table 1-14 compares the laptop expansion buses.

Table 1-14  Laptop Expansion Buses

Printers

There are many kinds of printers. The A+ exam focuses on a few common ones: laser, inkjet, impact (dot-matrix), solid ink, thermal, and dye-sublimation. The following is a list of common printer measurements:

• Pages per minute (PPM): Measures printer speed.

• Characters per second (CPS): Measures printer speed in impact (dot-matrix) printers.

• Dots per inch (DPI): Measures quality (resolution).

• Mean time between failures (MTBF): Measures reliability.

• Cost per page (CPP): Measures the price of each printed page. A proper measurement of CPP takes into consideration the cost of ink, paper, electricity, and scheduled printer maintenance.

Laser

Laser printers are good balance between cost and quality. They are quiet, reliable, and produce high quality printouts. Laser printers are not cheap, and toner can be pricy. Except for the initial costs, the actual CPP is low. Table 1-15 outlines the six steps of the laser-printing process with a helpful mnemonic.

Table 1-15  Laser Printing Process

Another mnemonic that is used to remember the Laser Printing Process: Cool Cowboys Will Drive Their Fords.

Inkjet

Inkjet printers include either thermal or piezoelectric nozzles. Thermal nozzles boil the ink and jets of steamed ink shoot onto the paper. Piezoelectric nozzles energize crystals that vibrate and control ink flow.

Impact Printers

A dot matrix printer uses a group of pins that strike a ribbon against the paper. When the pins are used in combination, they create shapes of letters. Daisy wheel printers have a wheel of letter symbols and numbers that rotate into position, and then the solenoid hits the letter into the ribbon and onto the paper. Impact printers are measured in CPS, not PPM. Near letter quality (NLQ) is the best quality a dot matrix printer can have. Impact printers are used on carbon copy paper because the impact travels through to the carbon copies beneath the original paper.

Solid Ink

Solid ink printers use a combination of laser and inkjet technologies. The solid ink is melted and sprayed (written) to a drum that is transferred onto the paper. These printers are used for posters and other large format, high quality photos.

Dye Sublimation

Dye sublimation is a process that prints the page four times each with a different color of ink. This produces long lasting, high quality images.

Thermal

Thermal printers are used most often on point-of-sale systems, thermal printers print receipts, and other inexpensive continuous feed outputs, such as those produced by EKGs, label makers, and old fax machines. The paper is stored on rolls and is treated so that heat darkens it.

Printer Connections

Regardless of the physical connection, the drivers must be installed on the PC from which the print job is sent. Drivers can be found on the installation CD or on the manufacturer’s website. Printer drivers and printer firmware can be updated based on the manufacturer’s recommendation. The three primary methods to connect to a printer are

• Directly connected to a PC via USB, parallel, FireWire, or infrared (IR).

• Directly connected to a remote networked PC that acts as a print server for the network.

• A networked printer that has a NIC and is a fully capable network device.

USB is the most common method to connect a printer because of the autoconfiguring nature of the USB interface. The entire process is /Parallel (ECC and ECP)/ IrDa.

Local Versus Network Printer

TCP/IP printers are controlled by a print server. Print jobs are sent to the print server, which are forwarded to the printer. A formal print server is a standalone PC with a locally connected printer. Many print servers are integrated into the printer, which eliminates the need for the additional computer and simplifies user management. Print jobs are directed to either uniform (or universal) naming convention (UNC) or an IP addresses. A UNC is always formatted with backslashes, such as hostnamesharedfoldersharedresource.

Printer Maintenance

To improve longevity and reliability, it is important to keep printers clean, supplied, and updated. Note: Always turn off and unplug the printer before cleaning it. Table 1-16 outlines printer maintenance.

Table 1-16  Printer Maintenance