Computer Repair Mastery Course
The hardware required to set up a Linux system mirrors a typical PC installation. It starts with the motherboard, which should be an Intel 80386 or better (or use one of the Intel workalikes like AMD or Cyrix). Remarkably, Linux will even run on a slow 80386SX, although slow is the operative word. For application development work, though, an 80486DX or better is recommended due to the high CPU usage of the compiler and linker. The same recommendation applies to X users because X is a notorious CPU hog. You can compile applications on an 80386, just as you can run X on one, but the performance can sometimes deteriorate to the point of annoyance. For a realistic system running X and application developments, consider a fast 80486DX (50MHz at least) or a Pentium. Linux supports both ISA (Industry Standard Architecture) and EISA (Extended Industry Standard Architecture) motherboards, but doesn't support MCA (IBM's MicroChannel Architecture) at the present time. Linux also supports VESA...
Most laptops and some less-expensive desktop PCs include built-in video, audio, and network support right on the motherboard. This practice lowers power requirements and simplifies the design, although these units often don't have all the power and features of more expensive PCI cards.
Motherboards come in a variety of shapes and sizes. Just as importantly, motherboards have small holes through which you insert screws to attach the motherboard to the computer's case. These holes are often referred to as the mount points of the motherboard. Motherboards also require certain types of connectors for keyboards and other external devices. Finally, motherboards have differing requirements in terms of power supply connectors. Collectively, these characteristics determine the motherboard's form factor. In theory, motherboards of just about any form factor can be designed to use just about any CPU or bus type, although the size requirements of components make certain combinations impractical. In reality, certain combinations don't appear because certain technologies (like 80386 CPUs or the VL-Bus) died out before specific motherboard form factors (like ATX) came into being. Linux isn't particularly concerned with the motherboard form factor per se, although Linux can work...
Caution Most PCs attach USB ports directly to the motherboard and if you make a mistake when building your own device
Serial port device This covers a wide range of different devices, including home-brew transmitters, and because they process serial data directly, they don't need any specific driver code. Typical circuits are available from the LIRC web site. If you're unsure about connecting your own electronics onto your PC motherboard, you can buy serial PCI cards, which offer a level of protection against rogue electronics.
With kernel 2.6, hardware RAID devices are supported with the Device-Mapper Software RAID support tool (dmraid), which currently supports a wide range of motherboard RAID devices. Keep in mind that many hardware RAID devices are, in effect, really software RAID (fakeraid). Though you configure them in the motherboard BIOS, the drivers operate as software, like any other drivers. In this respect, they could be considered less flexible than a Linux software RAID solution, and they could also depend directly on vendor support for any fixes for updates. The dmraid driver will map your system to hardware RAID devices such as those provided by Intel, Promise, and Silicon Magic and often included on motherboards.
Each of the major motherboard layouts described in Chapter 2 requires a different case type, although a few cases are designed to support more than one motherboard form factor. The form factors you're most likely to encounter include AT and Baby AT The AT and Baby AT form factors were the most popular in desktop and tower designs through 1995. The AT motherboard form factor is larger than the Baby AT form factor, and requires a larger case. Cases capable of holding full AT motherboards tend to be mid-size or full towers or desktop designs. Cases that can hold full AT motherboards can also almost invariably support Baby AT motherboards. These motherboards can also be used in compact mini-tower cases. I don't recommend buying a new AT or Baby AT case today unless you already have a matching motherboard. In this case, because the AT and Baby AT designs are now obsolete, I recommend you locate a case that can handle either AT or ATX motherboards, so that you don' t restrict your choices...
One of the most important features of a motherboard is its physical form factor, or its size and shape and the locations of key features. Many manufacturers, particularly major brands, use proprietary form factors, which should be avoided. If you buy a machine that has a proprietary motherboard and you need to replace it due to a repair or upgrade, you will find your selection limited (or non-existent) and overpriced. Some manufacturers undoubtedly use these proprietary designs to lower their manufacturing cost by eliminating cables for serial, parallel, and other I O ports others may have more sinister motives. The older AT (or baby AT) form factor motherboards are interchangeable, but have very little printed circuit board real estate along the back edge of the machine on which to mount connectors. The case only has holes to accommodate the keyboard and maybe a mouse connector. The newer ATX standard has many advantages. Although an ATX motherboard is approximately the same size and...
The term bus has several different but related meanings in computer circles. Earlier in this chapter, I used the word in reference to the speed of the interface between the CPU and the motherboard. Another meaning relates to the physical and electrical interface between the motherboard and the various plug-in boards you can add to the motherboard. On most computers, you use such boards to provide a variety of both critical and less-critical functions, such as a video board, sound board, and so on. There are half a dozen major bus types. Most motherboards implement two or three of them, but a few are restricted to just one bus type. A few motherboards, mostly those in specialized products and notebooks, contain no expansion bus slots at all. They usually implement the electronics involved internally in order to support features such as video and audio. Some busses are in common use today, but others are largely relics of the past. You might encounter these outmoded busses on 80486 and...
Your motherboard should include at least 16 MB of RAM for optimum Linux performance. Some users have managed to coax Linux into working on systems with as little as 4 MB of RAM. However, if your system has less than 16 MB of RAM, you probably won't be pleased with its performance. If you plan to run X, you may wish to install more than 16 MB of RAM - perhaps 64 MB. Although X operates well with 16 MB of RAM, you can open more windows and switch between them more quickly if you have additional memory. A handful of motherboards presents special problems when installing Linux. Generally, the problem stems from a bad BIOS, for which a fix is often available. Check the Debian Project web site for details.
All circuit boards in a computer owe their electronic identities to one or more chipsets they carry. A chipset is, as the name implies, a set of one or more chips that implement most or all of the functions of the board. In the case of a motherboard, the chipset provides functions such as
Your system mainboard, or motherboard, is the heart of your computer. It contains all the essential devices that make your system run, including the BIOS, CPU, RAM, and caching. The following section gives you a quick overview of these components, and many special considerations for Linux installations. BIOS (Basic Input Output System) is built-in software on the system mainboard that contains all the code required to control most of the basic devices and operations, and provides the interface to the underlying hardware of your server for the operating system. Modern systems contain flash BIOS, and you can access three possible sources for a BIOS update Your system vendor (for major brand systems), your motherboard vendor, or your BIOS vendor (if you've already purchased a replacement BIOS chip). Contact the system or motherboard vendor for the flash BIOS file that you must download. Most major system vendors have a database of models and the matching BIOS files.
As an electronic engineer and a do-it-yourself kind of person, I have always enjoyed using the computer to control external hardware. Ever since the days of my father's Apple IIe, I have been looking for another platform where I could connect my custom circuitry and write my own driver software. Unfortunately, the PC of the 1980s wasn't powerful enough, at either the software or the hardware level the internal design of the PC is much worse than that of the Apple II, and the available documentation has long been unsatisfying. But then Linux appeared, and I decided to give it a try by buying an expensive 386 motherboard and no proprietary software at all. At the time, I was using Unix systems at the university and was greatly excited by the smart operating system, in particular when supplemented by the even smarter utilities that the GNU project donates to the user base. Running the Linux kernel on my own PC motherboard has always been an interesting experience, and I could even write...
The boot sequence in the BIOS (basic input output system) may be incorrect. Information about changing the BIOS settings is provided in the documentation of your motherboard and also in the following paragraphs. The BIOS is a piece of software that enables the very basic functions of a computer. Motherboard vendors provide a BIOS specifically made for their hardware.
Once you've decided on the approximate specifications for a computer and you've set a budget, you can begin deciding on exact specifications. If you possess the necessary knowledge, I recommend indicating manufacturer and model numbers for every component, along with one or two backups for each. (RAM, however, is close to being a commodity few people shop for RAM by brand, although the type of RAM is important.) You can then take this list to a store and compare it to the components included in particular systems, or you can deliver your list to a custom-build shop to obtain a quote. If you don't have enough in-depth knowledge of specific components, you can omit the make and model numbers for some components, such as the hard disk, CD-ROM drive, monitor, and motherboard. You should definitely research Linux compatibility with video cards, network cards, SCSI host adapters (if you decide to use SCSI components), and sound cards (if the computer is to be so equipped). These components...
Select an enclosure that matches your motherboard form factor and has sufficient drive bays and wattage to accommodate your needs. Many case manufacturers have retooled their AT form factor cases to accommodate the ATX motherboard if you order an AT case, you may receive a newer ATX design with an I O shield that has cutouts for AT keyboard and mouse ports. For most applications, Mini-Tower, Mid-Tower, or Full-Tower cases are likely to be the preferred choices. For some applications you may want server or rack mount designs.
Following is a list of items you may need information about. Get as much information on each item as you can manufacturer, model number, size (megabytes, gigabytes, and so forth), number of buttons, chipset (for cards), and so on. Some items, such as the network interface card, may be built into the motherboard.
The hardware node is the principal building block of the physical cluster system. After all, it is the hardware node that is being clustered. The node incorporates the resources that provide both the capability and capacity of the system. Each node has one or more microprocessors that provide the computing power of the node combined on the node's motherboard with the DRAM main memory and the I O interfaces. In addition the node will usually include one or more hard disk drives
SCSI host adapters often include their own BIOSes and setup utilities, which are separate from the motherboard BIOS. The SCSI setup utilities usually have setup options you can adjust by pressing a key sequence at a particular point in the boot process. Watch your boot displays or consult your SCSI adapter's documentation for details. Disk settings There are two common hard disk settings you may need to adjust. The first specifies the size of the disk. An auto-detection feature normally works well for this. The second setting determines how the BIOS interprets the disk's cylinder head sector (CHS) addresses. On most BIOSes, a linear block addressing (LBA) mode is the best choice. If you use SCSI hard disks, the main motherboard BIOS won't detect them. This is normal the SCSI BIOS provides the necessary support. On-board ports Modern motherboards include RS-232 serial, parallel, USB, EIDE, and frequently other types of ports. You can enable or disable these or change their settings...
Architecturally, though, the 80386 added the features that are most important for running an advanced OS such as Linux. These features include 32-bit memory addressing and protected-mode operation, which makes multitasking much easier to implement. 80386 CPUs did not include math coprocessors (also known as floating-point units, or FPUs). These devices handle floating-point arithmetic, and greatly speed up mathematical computations. It was, however, possible to add FPUs to most 80386 motherboards. In theory, Linux requires an FPU but the kernel has optional FPU emulation. In practice, you can run Linux even on a 386 without an FPU, if you've compiled the appropriate support into the kernel. The 80386 was available in two major forms the SX and the DX. The SX was a lower-level CPU with a pinout to match that of the 80286. The idea was to let computer manufacturers modify existing 80286 motherboard designs in order to bring a product to market more quickly and inexpensively than would...
The minimum realistic system requirements for Linux are a motherboard with an 80386SX processor or better, 2M of RAM or more, a floppy disk drive, a hard drive with 40M or more, and a video card and monitor. Most user's systems exceed these requirements. The following sections examine the hardware requirements for a Linux system in a little more detail.
To boot from a CD-ROM or DVD-ROM, you may first have to change the boot sequence setting in your computer's BIOS so that the computer will try to boot first from the CD-ROM. This requires some technical ability and knowledge of how to set your motherboard's BIOS configuration.
Linux recognizes CD and DVD drives upon booting if they are attached to your computer's motherboard with proper cabling and if they are assigned as either a master or slave on an IDE channel. Look through your kernel boot message for the drive device assignment, such as the following
You can obtain the commercial OSS drivers from 4Front Technologies (http www.opensound.com). You can obtain an evaluation copy of the 4Front drivers from their web site. This copy will work for a limited period of time, then it will disable itself. The package includes an installer utility and precompiled binary kernel modules. If your sound card is a basic low-end model, the drivers may cost more than the card, but it may be simpler to install commercial OSS drivers than to replace the card, particularly if the sound card is integrated on the motherboard and you lack a free slot for a replacement card. The OSS drivers may also be worthwhile if your sound card is an expensive model with advanced features supported by the drivers.
Ubuntu will work out-of-the-box with nearly every Intel-or PowerPC-based motherboard and laptop drivers for thousands of different types of hardware peripherals are included. But you can sometimes run into problems if Linux does not recognize a hardware item, if Ubuntu does not correctly initialize the hardware, or if an initialized item is incorrectly configured. For these reasons, some hardware items are prone to creating problems during an install. In the sections that follow, you learn some important pointers for avoiding these problems or resolving those that do occur. Motherboard-Based Hardware Common modern (1996-onward) PC motherboard form factors are designed according to industry-assigned specifications (usually from Intel), and are ATX (129.6 inches) MicroATX (9.69.6 inches) and FlexATX (97.5 inches). One of the newest and even smaller motherboard forms is from VIA Technologies, Inc.the mini-ITX (approximately 6.56.5 inches), which has an embedded CPU. CPUs commonly used in...
Existing hardware before attempting a migration to Linux. Not only do you benefit from the collected information, but you might also be able to sidestep or anticipate problems before, during, or after installation. Problems are most likely to occur with newer hardware, cutting-edge hardware such as new motherboard chipsets and video cards, or extraneous hardware such as operating systemspecific scanners, printers, or wireless devices.
To start your quadraphonic wall of sound, you need to have a sound card in your PC. A sound card can be an add-in PCI (or even ISA) card, or it can be integrated on your motherboard. Your card will have a ton of uses from gaming to audio video playback. Having a multimedia system just isn't the same without sound. Joystick MIDI (15-pin connector) Connects a joystick for gaming or MIDI devices. (Some sound cards no longer have these ports because they are now available from most motherboards.)
If your motherboard contains only one disk controller and uses it for the hard drive and the CD DVD device, you won't be able to add a second hard drive on that controller. Usually you can find plug-in disk controller cards to add a second controller to the workstation. You'll need to do that if you want to add another hard drive. If your motherboard contains two disk controllers, you can purchase a second hard drive and easily connect it to one of the controllers to use for Ubuntu. The Ubuntu installation process detects the empty hard drive and will format it for Ubuntu. If both of the disk controllers already contain one device, you'll need to use a master slave configuration to add the second hard drive. This process requires a controller cable that has three plugs one for connecting to the motherboard and two connectors to plug devices into.
All modern IA-32 motherboards come with at least two built-in ATA controllers. Therefore, using an ATA disk is just a matter of setting a jumper or two, connecting the disk to the motherboard via an ATA cable, and attaching a power connector to the hard disk. Because most motherboards have only two ATA controllers, and each controller can handle just two drives, most motherboards can support only four ATA devices. Most computers have a hard disk and a CD-ROM drive. Adding a Zip or other removable-media drive and a tape backup drive leaves no room for expansion. In order to move beyond the four-drive limit, you must add a separate ATA controller, as described in the next section, Controllers and Host Adapters. In this situation, SCSI offers the advantage of supporting more devices per chain, and hence per IRQ.
Hard disks interface to computers via components known as controllers or host adapters. (The former term is usually applied to ATA interfaces, whereas the latter applies to SCSI interfaces.) Until the mid-1990s, these devices were usually separate cards that plugged into motherboards. Today, though, all new IA-32 motherboards ship with ATA controllers built in, and some motherboards include SCSI host adapters, as well. Even when a motherboard includes a controller or host adapter, though, you may want to add another one or replace an existing one.
In most cases, your motherboard's ATA controller will work just fine for handling ATA devices. For a typical setup, then, there's seldom any need to change the configuration. There are reasons you might want to add to or replace your motherboard's ATA controller, though Lack of Linux Driver Support All ATA controllers work to a minimal extent using an old compatibility mode that dates back to the days of the ST-506 interface. By today's standards, though, this mode is extremely slow to get the most out of an ATA controller, you need Linux support for it. Linux includes such support for most ATA controllers, but occasionally this support may be missing or buggy. This is particularly likely to be true if you buy a motherboard that uses a brand-new chipset for which Linux ATA drivers haven't been written. In such a case, you might want to disable the built-in ATA controller and use an add-on card instead. Too Many Disks As noted earlier, it's easy to consume all four devices that can be...
When considering an upgrade, check your existing devices' documentation to learn which speeds they support. You can buy a more capable ATA controller than you need now, but try to put devices of similar levels on the same bus whenever possible. For instance, if your motherboard supports 33MB S transfers and you buy an ATA-6 (100MB s) card to supplement it, put slow devices on the motherboard and fast ones on the expansion card.
When Fedora starts, you will at first see a great deal of text information scrolling rapidly across your display as Linux examines and adjusts to your CPU, mainboard and memory configuration, and other hardware. Fedora then displays a progress bar in the center of your screen to show its progress as it launches system services and performs other housekeeping tasks (see Figure 3.2). This process might take several minutes the first time you start Linux. On subsequent boots, it will take anywhere from a few seconds to a minute or so the process is repeated each time you start Linux. If you customize your installation or performed a Server installation, you might see a text display containing more detailed information instead of a progress bar.
Most laptops with Intel Celeron or better processors should be able to run plain Linux without any problems. If you want to install X.Org X11, however, you may have some trouble if X.Org X11 does not support the video card (on a laptop, video circuitry is built into the motherboard) and the pointing device. You can use the VESA driver to get X working on most laptops even if X.Org X11 doesn't natively support the laptop's graphics chipset. Also, nowadays, most laptop pointing devices can at least emulate a standard PS 2 Mouse, so all pointing devices should work with XFree86.
Over the years, a number of proprietary and little-used motherboard layouts have emerged. 2 computer that uses such a unique motherboard form factor. g A low-profile form factor used in years past was known as LPX. This design, like the newer NLX design, used a riser, but placed it in the middle of the motherboard. LPX boards weren't quite perfectly standardized, so it's not always possible to swap one LPX motherboard for another. If you want to buy or build a new low-profile computer, I recommend you use NLX rather than LPX. I recommend you avoid proprietary and unusual motherboard form factors, with the possible exception of WTX, which has the potential to become more common in late 2000 or early 2001. Proprietary boards often require unusual cases, which in turn often require unusual face plates on floppy disks, unusual power supplies, and so on. Replacing such components can be an expensive and of proprietarytime-consuming proposition.
If you have a motherboard already and aren't sure what chipset it uses, look at the largest chips that are permanently soldered to the motherboard. These should bear some identifying marks. For instance, Figure 2.11 shows one of the major chips on the motherboard depicted in Figure 2.1. This chip clearly identifies the chipset as being from VIA, and, in fact, it's part of the VIA MVP3 chipset. You may need to browse the chipset manufacturer's Web site to locate a reference to a particular chip ID code.
One way to add computing power to a computer is to add additional processors to a motherboard that supports Symmetric Multiprocessing (SMP). SMP allows you to share the processor's workload across up to 16 processors in a single computer. In practice, because of limitations of the x86 architecture, actual implementation has not exceeded eight processors. Still, that's enough to significantly speed up programs written to support SMP or systems that run multiple CPU-intensive programs. Only multithreaded programs will truly benefit from SMP. Multithreading, also simply referred to as threading, is the process of cloning processes to split the workload within a program into separate processes that can be routed to separate processors in an SMP system. Basically, the rule is processes and kernel threads are distributed among processors user-space threads are not. If you notice that your single processor is idle much of the time because of a slow disk drive, the system probably won't...
Note You might need to configure the motherboard's bootup settings to check for a CD DVD inserted in the CD DVD drive. Consult the motherboard documentation for instructions on setting the boot device order. This setting simply defines the order in which the computer will look for operating system files to load typically you want your operating system to be started from a hard drive, but with a new computer there is usually no data on the hard drive. So you must tell your computer to look for OS files on a CD DVD. Your Ubuntu CD DVD will contain the proper files for it to start up. (This is covered in more detail in the next section.)
The devices described in this chapter usually interface through connectors on an IA-32 system's motherboard, as depicted in Figure 3.1. These connectors are accessible from the back of a typical computer. The port connectors on some older systems were placed on expansion cards. Even today, such cards may be used to add extra ports, should you need more than the standard mix. Some systems place one or more USB connectors on the front of the computer, instead of or in addition to the back-panel USB connectors. Some very old RS-232 ports, as well as the RS-232 connectors on most external devices, use wide 25-pin connectors rather than the 9-pin connectors shown in Figure 3.1.
USB Host Controller Drivers The host controller driver (HCD) is the driver for USB itself, as implemented by a chipset on your motherboard or a USB expansion card. As of the 2.5.54 kernel, Linux supports three HCDs Enhanced Host Controller Interface (EHCI), Open Host Controller Interface (OHCI), and Universal Host Controller Interface (UHCI). EHCI handles the USB 2.0 protocol (which is capable of speeds of up to 60MB S, as opposed to 1,5MB s for USB 1 .x). UHCI is the USB 1 .x controller used by Intel and VIA motherboard chipsets. OHCI is the USB 1 .x controller used by most add-on cards and motherboards that use chipsets from manufacturers other than Intel or VIA. If your system has USB 2.0 support, you need both the EHCI driver and either the UHCI or OHCI driver.
Back in the DOS era, PCs had serial and parallel ports controlled by separate controller chips on the motherboard. Like everything else in the machine, these controller chips could be directly accessed by any software running under DOS. By writing bit-mapped control values to the chips and creating custom interrupt service routines, one could create custom ''fine-tuned'' serial interface software, which enabled the plodding 300-character-per-second dial-up modems of that time to work as fast as they were capable. That was routine, but with some cleverness, you could make standard computer hardware do things it was not really intended to do. By studying the hardware controllers for the machine's parallel port, for example, I was able to write a two-way communications system in assembly that moved data very quickly from one computer to another through their parallel ports. (This was actually pre-PC, using CP M for the Z80 CPU.)
Sub-Optimal Port Settings Modern parallel ports support several different operating modes standard parallel port (SPP), enhanced parallel port (EPP), and enhanced capabilities port (ECP). For ports built into the motherboard, you set the mode from the BIOS's setting screen, typically accessed by pressing Delete or some other key early in the boot process. For the best performance, select ECP mode, or at least EPP SPP produces distinctly lower transfer rates than other modes.
Linux provides a system date and time your computer hardware provides a hardware clock-based time. In many cases, it is possible for the two times to drift apart. Linux system time is based on the number of seconds elapsed since January 1, 1970. Your computer's hardware time depends on the type of clock chips installed on your PC's motherboard, and many motherboard chipsets are notoriously subject to drift.
If the machine has a BIOS password and you cannot boot and log in to it, you can bypass the password easily in several ways. The most common ways involve removing the CMOS battery, modifying jumper settings, and using various software utilities. If attackers are patient and have about 10 minutes to wait, they can remove BIOS passwords simply by removing the CMOS battery. At that point, the motherboard discharges its stored electricity (from capacitors), and the password is erased and the BIOS is reset to factory defaults.
How big should the swap space partition be No single number works for all installations, unfortunately. Generally, because the swap space is used as an extension of physical RAM, the more RAM you have, the less swap space is required. Add the amount of swap space and the amount of RAM together to get the amount of RAM Linux will use. For example, if you have 8M of RAM on your machine's motherboard and a 16M swap space partition, Linux will behave as though you had 24M RAM.
The Hardware Information applet organizes the data according to hardware type, such as Disk, Keyboard, Network Card, and so on. Some hardware components are organized under the heading of the particular bus system they use, such as PCI or USB. This is especially true of some of the underlying system components, such as motherboard chipsets.
The BIOS also contains routines to help you configure how your hardware operates. This portion of the BIOS is known as the CMOS setup utility because it sets options that are stored in complementary metal oxide semiconductor (CMOS) memory. This is a small area of nonvolatile memory on the motherboard. Options you can set in the CMOS setup utility include the order in which the BIOS looks for boot devices, memory timing characteristics (particularly on older motherboards), and what motherboard devices (EIDE ports, parallel ports, and so on) are active. Most CMOS setup utilities are broken down into a number of sub-sections. For instance, Figure 3.4 shows a typical main screen. Each option along the top (Main, Advanced, and so on) corresponds to a screen full of options. Some CMOS setup settings affect how Linux handles the hardware in question, and so are important even in Linux. The details of CMOS configuration vary a great deal from one motherboard to another, both because the...
As I mentioned earlier, many plug-in boards have their own ROMs. On modern boards, these ROMs are generally EEPROMs, although they can be other types on older products. Like the motherboard's ROM, expansion card ROMs contain code that's used by the device to help control itself. Some expansion card ROMs are also used in conjunction with the motherboard's ROM. For example, SCSI host adapters and some network adapters include boot BIOSes that latch into the computer's boot sequence. Because SCSI host adapters vary so much in their design, the standard motherboard BIOS can't control SCSI devices, including SCSI hard disks The SCSI boot BIOS provides expansion BIOS code to allow a computer to boot from a SCSI hard disk. The SCSI adapter's BIOS can also provide a user interface similar to the CMOS setup utility. This utility typically provides a way to configure the SCSI host adapter, and can include options to configure or modify SCSI devices. For instance, many such utilities let you...
One of the problems associated with ACPI is the different power events configured by different laptop and motherboard manufacturers. One way to review available power events is from the list of files installed from the acpi-support package. From the command line, you can review this list with the following command (if the package is installed)
In theory, any case advertised for a specific size motherboard should be large enough to hold that motherboard. Sometimes, however, the case and motherboard combine to make an unusually tight fit, or some case component might block an important part of the motherboard. Such difficulties are more common in AT and Baby AT cases than in later designs, and they're more common in small cases than in large ones. Ideally, you should buy your case and motherboard from the same dealer, so that if you have problems you won't have dealers pointing fingers at each other, each refusing to accept a return. If you have the luxury of examining the motherboard you're considering buying mated to your case of choice, watch for some features in particular Power supply clearance On some cases, the power supply overhangs the motherboard. Be sure that there's adequate clearance for any components that might reside under the power supply. Drive bay clearance Sometimes, 3.5-inch drive bays abut the...
I've already warned you against non-standard motherboard and case form factors. Some cases, however, are non-standard in a more subtle way. Such cases might support standard motherboard sizes but use other non-standard components. For instance, many computers from large computer companies use front panels that curve in interesting ways. These curves often necessitate the use of unusual curving front panels on CD-ROM drives and other removable media devices. If you need to replace such a drive, you might be faced with a difficult job when it comes time to add the new drive, because it might not fit, or at least ruin the aesthetics of the case.
Let's face it As enjoyable as the experience of staring at a dormant computer is, the real fun starts when you turn on the computer. As with any electronic device, opening the electron floodgate is the first step to fun. A computer, however, has much more stuff to do than your toaster oven. Rather than act as a simple heating element, your computer has to check all those gizmos that you (or the manufacturer) plugged into your computer's motherboard. After the initial power-up, the computer performs some simple hardware tests (called the POST, or Power-Up Self Test) to determine whether those various components are working properly.
To build a customized kernel, unpack the kernel sources somewhere that has enough room (say, in usr local src linux). Run a make menuconfig (or, if you're running X, make xconfig). Select your drivers carefully (hitting Y for built-in drivers, and M for loadable modules.) Remember that you're building a kernel for a server and don't include extraneous drivers. Does your server really need sound support, even if it is built into your motherboard What about USB Unless you have a specific use for a particular piece of hardware that is directly related to its job as a server, don't bother installing a driver for it. You should also consider disabling unused hardware in the BIOS, wherever possible, to conserve system resources and reduce the possibility of hardware resource conflicts.
Until recently, dial-up was the most common method for an individual to get on to the Internet. Many computers had dial-up modems built into the motherboard or had serial ports where a modem could easily be connected. Many computers today do not include modems, but serial or USB modems can be purchased for just a few dollars if you need to use dial-up.
When mounted in a case, the end of the hard disk with the power and EIDE or SCSI interface connectors faces toward the appropriate motherboard or expansion card, so that the cables can be easily connected. Unfortunately, this placement often makes it difficult to access the jumpers on the opposite end of the drive, and units with side-mounted jumpers can be even more difficult to configure. You should be sure that you've set all the jumpers correctly before mounting a hard drive in the case.
77 although this is an identity mapping on an i386, on another architecture it could map between the physical CPU number, corresponding to its place on the motherboard, and its logical number, as used within the kernel. 81 although this is also an identity mapping on an i386, on another architecture it could map between the logical number by which a CPU is identified within the kernel and its physical place on the motherboard.
The Scalable Coherent Interface is an IEEE standard originally designed to provide an interconnect for cache-coherent shared-memory systems. One of the first major deployments of SCI was on the Convex Exemplar SPP-1000 in 1994. SCI has not been able to gain ground in traditional networking markets, despite its ability to serve as a general-purpose interconnect. The main reason Beowulf designers choose to use SCI is for its low latency of well under 10 s. Current PC motherboard chip sets do not support the coherency mechanisms required to construct an SCI-based shared-memory Beowulf. But if that functionality is ever added to commodity motherboards, we may see an increase in the popularity of SCI as researchers experiment with shared-memory Beowulf systems. Seven years ago, SCI delivered many clear advantages, but today commodity network technology has caught up, although SCI still delivers significantly lower latency. Dolphin Interconnect offers an SCI-based interconnect for Beowulf...
Although the actual boot loading mechanism for Linux varies on different hardware platforms (such as the SPARC, Alpha, or PowerPC systems), Intel-based PCs running Ubuntu most often use the same mechanism throughout product lines. This process is accomplished through a Basic Input Output System, or BIOS. The BIOS is an application stored in a chip on the motherboard that initializes the hardware on the motherboard (and often the hardware that's attached to the motherboard). The BIOS gets the system ready to load and run the software that we recognize as the operating system.
External drives are easier to install because you need only add the interface board to an empty slot on the motherboard (assuming you need a new interface board) and attach the cable from the CD-ROM drive to the port on the back of the board. You add SCSI drives to the external SCSI chain. Make sure you have the proper connectors to add the CD-ROM drive to the chain. Also, when adding a SCSI CD-ROM, make sure that you set the SCSI ID to an unused value (see Chapter 7, SCSI Devices, for more information on SCSI IDs). The SCSI ID is usually set with jumpers on internal CD-ROM drives, although some drives use DIP switches. External SCSI CD-ROM drives use a variety of methods to change SCSI ID numbers. The most popular method is a dial that shows the proper ID.
Once you have determined that your model of sound card is supported, you can begin the process of making it available to Linux. Install the sound card, if necessary. This procedure usually involves nothing more complex than placing the card in an available slot on the motherboard. Because Linux uses its own device drivers, installing the DOS-based software has no effect on the card under Linux.
Most people think of printers, scanners, and cameras as the most common peripheral devices. In the early days of computing, that is, before the development of the personal computer, the base system consisted of the motherboard, the central processing unit, and the memory. Taking this into consideration, the keyboard and mouse were originally considered peripheral devices. To this day, some still consider these two devices to be peripherals because so many of them require device drivers to be installed with them.
The Ultra3 SCSI variants represent yet another doubling of SCSI bus speed, to 80MB s and 160MB s for the Narrow and Wide variants, respectively. As with Ultra2 SCSI, however, Ultra3 devices are available almost exclusively in Wide format, which is often referred to as Ultra 160. In fact, 160MB s exceeds even the theoretical maximum 132MB s transfer rate of a standard 32-bit PCI bus, so some Ultra3 host adapters use 64-bit PCI busses rather than the more common 32-bit variant. Be sure you can use such a host adapter on your motherboard before buying one.
Most BIOSes have an option to set a password that must be entered before the system will boot or before BIOS settings can be changed. Setting this can go a long way toward preventing tampering, but it's not perfect. Motherboard BIOSes can be reset by modifying a jumper setting, so an intruder who can open the case can overcome this measure.
The parallel connector is not isolated from the computer's internal circuitry, which is useful if you want to connect logic gates directly to the port. But you have to be careful to do the wiring correctly the parallel port circuitry is easily damaged when you play with your own custom circuitry unless you add optoisolators to your circuit. You can choose to use plug-in parallel ports if you fear you'll damage your motherboard.
Make sure not to specify more than the actual memory size here, otherwise the kernel will crash. If one has more than 64MB of memory, e.g. 128MB, unless one executes mem 128M at the boot prompt or includes a similar append line in etc lilo.conf, old kernels and or a motherboard with an old BIOS will not use memory beyond 64MB.
Now that we've discussed digital audio concepts, let's look at the hardware used for audio. Sound cards follow a history similar to other peripheral cards for PCs. The first-generation cards used the ISA bus, and most aimed to be compatible with the SoundBlaster series from Creative Labs. With the introduction of the ISA Plug and Play (PnP) standard, many sound cards adopted this format, which simplified configuration by eliminating the need for hardware jumpers. Modern sound cards now typically use the PCI bus, either as separate peripheral cards or as on-board sound hardware that resides on the motherboard but is accessed through the PCI bus. Some USB sound devices are now available, the most popular being loudspeakers that can be controlled through the USB bus.
Direct Memory Access (DMA) allows internal peripherals to access memory without the processor needing to execute instructions for each transfer. There are two types of DMA one uses the DMA controller on the motherboard and the other uses a busmaster controller on the peripheral card. I suggest you avoid using the motherboard DMA controller if possible. There are a limited number of DMA channels, which can make it hard to find a free channel. This form of DMA is very slow. And this form still requires short interrupt latencies (the time between when the peripheral asserts the interrupt line and the processor responds) when the DMA controller reaches the end of the buffer, you need to quickly reprogram it to use another buffer. This controller requires multiple bus cycles per transfer it reads a byte of data from the peripheral and then writes it to memory, or vice versa, in two separate operations and inserts wait states as well. This controller only supports 8- and 16-bit transfers.
SMP Support If your motherboard has more than one CPU, it's important that you select this option. If this option is not enabled, Linux will use just one of the CPUs, which is obviously not very efficient. If you enable this option when it shouldn't be enabled, the kernel will run on most, but not all, single-CPU systems, but won't run as quickly as it would if configured for single-CPU operation. In the 2.5.67 kernel, you can specify how many CPUs your system has after selecting this option.
Note that the parallel port must not be in use by another device driver (such as lp0). You may need to unload the printer module or boot the system with the reserve 0x378,4 option at the boot prompt. If you are trying to use interrupts and are having trouble, check for conflicts with other devices (the interrupts on printer cards are usually not used for printers) and check your bios to make sure it is not allocated to the PCI bus instead of the ISA bus or motherboard.
The BIOS in many machines gives you some degree of protection from an unauthorized person modifying the BIOS or rebooting the system. When you set up the BIOS, look for a section named Security. You can probably add a BIOS password. If you depend on the BIOS password, lock the computer case. It is usually a simple matter to reset the BIOS password by using a jumper on the motherboard.
Option ROMs Some peripherals and motherboard components have specific read only memory (ROM) stored on the BIOS flash. This ROM contains code for initializing the peripheral or component. The BIOS is in charge of executing the option ROMs and ensuring that the corresponding devices are only available if the option ROMs are executed successfully.
With a DMA buffer in place and the card properly configured, the program triggers the sound card's DMA by toggling the driver's PCM output enable bit. The trigger feature is designed to allow applications to gain precise control over playback timing, but it doubles as a way to set off DMA transfers. Once the DMA controller has been started, it cannot be stopped without shutting down OSS. This is a flaw, in my opinion, but it is only a minor issue (to effectively stop playback, simply fill the buffer with zeroes). After this bit has been cleared and then reset, the DMA controller (either part of the sound card or a component of the motherboard's chipset) will repeatedly loop over the DMA buffer and send whatever it finds directly to the sound card. To play sound, we simply have to copy our samples into the DMA buffer.
When you first turn on a computer system, it loads a boot monitor or Basic Input Output system (BIOS) from storage on the motherboard. This storage is usually a programmable, read-only memory chip (PROM) or a section of flash memory that is present on the board. The BIOS or boot monitor is a very low-level, hardware-oriented application that does some basic hardware initialization, performs some amount of hardware testing and verification (often optional), waits for keyboard or console input for some predetermined period of time, and then usually begins to execute a set of predetermined instructions to load another program into memory. These instructions load another program into memory from a predetermined location such as a portion of flash memory or the Master Boot Record (MBR) of a storage device such as a hard drive or CD-ROM, and then specify the memory address at which to begin executing the program once it has been loaded successfully.
BIOS The BIOS (page 1025), which is stored in an EEPROM (page 1035) on the system's motherboard, gains control of a system when you turn on or reset the computer. After testing the hardware, the BIOS transfers control to the MBR, which usually passes control to the partition boot record. This transfer of control starts the boot loader, which is responsible for locating the operating system kernel (kept in the boot directory), loading that kernel into memory, and starting it running. The boot directory, which may be mounted on a separate partition, must be present for the system to boot Linux. Refer to Booting the System on page 511 for more information on what happens from this point forward.
Some serial devices are rare and nonstandard implementations of RS-232 ports. The problem with the standard implementation of RS-232 serial devices is that it's difficult to add ports beyond the two included on most motherboards. Adding third and fourth ports presents only minor difficulties. Most add-on ports come configured to share interrupts with the first two ports, but it's necessary to reconfigure these boards to use unique IRQs because Linux doesn't normally work well with this arrangement. Note Internal modems traditionally include serial port hardware along with modem hardware. Adding such a modem works just like adding a serial port. It's sometimes helpful to disable an unused motherboard serial port before adding an internal modem, so that the internal modem can take over the identity of one of the first two regular ports. This can normally be done in the
Once your system is turned off and open, locate the IDE cables that are attached to the EIDE interfaces on your motherboard (or, in rare cases, to an IDE or EIDE controller card). IDE cables are flat, 40-pin ribbon cables with two flat, notched connectors near one end and a similar connector at the other end. Most PCs have two IDE interfaces, known as primary (IDE-1) and secondary (IDE-2). The cable from each IDE interface can be attached to a maximum of two hard or CD DVD drives. If two drives are attached to a single cable, they must be configured as master and slave drives by connecting pins known as jumpers that are located on the back or bottom of the hard drive or CD-ROM drive. Master is the term used for the first drive on an IDE interface slave is the term used for the second drive on the IDE interface. By tracing cables and examining jumpers, you can manually identify how the drives are connected. To do so, follow each of the IDE cables from your motherboard back to any hard...
In most cases, workstation users will want to run the X Window System (X11). The ability to run X11 depends on compatibility with the video chipset on your video card or mainboard. Debian 4.0 includes version 7.1 of X.org, which includes better autodetection than the XFree86 X11 system previously used.
Linux uses the PNPBIOS defined in Plug and Play BIOS Specification Version 1.0A May 5, 1994 to autodetect built-in mainboard resources (e.g., parallel port resources). If you would like the kernel to detect and allocate resources to your mainboard devices (on some systems they are disabled by the BIOS) say yes here. The PNPBIOS can also help prevent resource conflicts between mainboard devices and other bus devices. ACPI is expected to supersede PNPBIOS some day. Currently, they coexist nicely. If you have a non-ISA system that supports ACPI, you probably don't need PNPBIOS support.
The system board speaker is another relatively fixed feature of the standard PC. Its audio signal comes from a 1.19318 MHz square wave. To get control over the speaker's pitch, this signal is divided by the number stored in the two-byte register located at I O address 42H. This register must be written to using two successive one-byte writes, most significant byte first. Whether the speaker is turned on or not is controlled by the bottom two bits of a very important one-byte register located at I O address 61H. Some of the bits of this register indicate parity errors in memory. Reports of these errors cause the system to halt Consequently, we don't want to flip one of them idly or accidentally. The and and or instructions are perfectly suited for changing some bits and leaving the others alone. For example, to turn the speaker on, the following three commands are needed
The PBX is built around a Blackfin STAMP development card, available off the shelf from Digi-Key for around 225 US. The Blackfin is a powerful DSP chip that runs uClinux. Sitting on top of the Blackfin STAMP card is a daughterboard, which contains interface hardware and the SD card socket. Into the daughterboard plugs FXO or FXS modules, one for each port. In this example, there are two FXS modules on the left and two FXO modules on the right. The color of each LED indicates the type of module inserted. Here's a brief review of telephony jargon The community is loosely organised under the Free Telephony Project, and it consists of private hackers, researchers and several companies who are donating time and other resources to the project. A series of hardware designs are being developed, for example, analog and ISDN interface hardware, and DSP motherboard designs. Significant software development work is also occurring, for example, open echo cancellation software and drivers for the...
Internal cabled devices typically attach to the motherboard or an expansion card. They usually require connecting at least two cables a power cable and a data cable. Power cables are keyed to prevent accidental backward insertion, as are some data cables. Some data cables, though, lack this keying. If you must use such a cable, check for a colored stripe along one edge, and insert it to match up with the pin 1 markings on both the device and the motherboard or card. You should always power off a computer before attaching internal cabled devices. Internal cabled devices are usually mounted to the computer's case using screws. Details vary from one computer to another. Sometimes you may need to partially disassemble a system to reach the screws, which can be a nuisance. For instance, I've seen mini-tower systems that require you to partially remove the motherboard to reach screws for 3.5-inch hard disks. If you've removed screws but you can't remove a drive, look for other areas (even...
One method of tuning involves adjusting the settings in your BIOS. Because the BIOS is not Linux and every BIOS seems different, always read your motherboard manual for better possible settings and make certain that all the drives are detected correctly by the BIOS. Change only one setting at a time. pci biosirq Some motherboards might cause Linux to generate an error message saying that you should use this. Look in dmesg for it if you do not see it, you don't need to use it.
Laptops are essentially miniaturized desktop computers. A laptop includes a motherboard, a CPU, RAM, a keyboard, a mouse (usually in the form of a touch pad or TrackPoint), a hard disk, a CD-ROM drive, a floppy drive, and a display. From a software point of view, these devices all work like their counterparts on a desktop computer. There are some limitations that are more common on laptops, though. These include the following
As with hard disks, Linux's support for a CD or DVD drive depends on the interface through which that CD drive connects to the PC's motherboard. CD and DVD drives come with four types of interfaces Proprietary CD-ROM interfaces In the early days of CD-ROM drives, many CD-ROM vendors provided their own proprietary interfaces between the CD-ROM drive and the PC's motherboard. Many sound cards included a built-in CD-ROM-drive interface, which is typically proprietary. The problem with proprietary interfaces is that someone has to develop a Linux driver specifically for each interface, whereas with a SCSI or IDE interface you can use a SCSI or IDE driver to access any SCSI or IDE device.
Configuring and setting booting behavior on some older Alpha systems requires changing jumper settings on the motherboard or changing system data stored in nonvolatile RAM, or both. You may need to change jumper settings initially for installation and again afterward to configure the system.
Available on systems set up for Tru64 Unix or Open VMS. The only exceptions are systems based around the UX motherboard, which have their own ARC BIOS firmware and the Digtal XL series, for which SRM was never released. SRM is the best environment for installing Linux, and the one we concentrate on in this appendix.
When you buy a desktop computer, you almost always have the option of replacing troublesome components. For instance, if your video card doesn't work to your satisfaction, you can remove it and install another card. Some desktop systems support some features through chipsets built in to the motherboard, but you can usually disable these features and install a separate card to handle these functions. Not so with notebooks. Because of the severe space constraints, notebook computers don't include conventional ISA or PCI slots. To some extent you can use a PC Card or possibly an external device to work around non-functional integrated components, such as a modem. Sound and video, however, can be virtually impossible to replace. It's critically important that any notebook computer you purchase use a video chipset that's supported by XFree86 or a commercial Linux X server. You might or might not consider sound support to be so critical but, if you do, you must be equally sure that Linux...
Fortunately, most notebook manufacturers make it clear what video hardware they use. Ads for notebook computers typically include this information. Because the video support is integrated into the motherboard, the ads usually specify the video chipset that's in use. This is precisely what you need to know to locate a Linux driver, as described in Chapter 12, Video Cards, and Appendix A, Linux Device Drivers. Sound chipsets are not always advertised quite as clearly as are video chipsets. Many manufacturers merely report that their notebooks have SoundBlaster-compatible sound, or they trumpet the manufacturer of the speakers, but don't mention who makes the sound chipset in use. In some cases the sound chipset is integrated into the motherboard chipset, and isn't well known to consumers. Many notebook computers sold in 2000 that use VIA chipsets, for instance, incorporate sound support from the VIA 82c686a, which is incorporated into some of VIA's recent motherboard chipsets.
The dmaspeed value refers to the rate (in MB s) at which the DMA (Direct Memory Access) transfers proceed. The default is 5MB s. Newer revision cards allow you to select this value as part of the soft-configuration older cards use jumpers. You can use values up to 10MB s, assuming that your motherboard is capable of handling it. Experiment with caution if using values over 5MB s.
The function shown in Figure 14.29, from arch i386 kernel apic.c, puts the motherboard back into PIC mode. It has an effect only on certain older boards, designated by the pic_mode flag being set (see Section 184.108.40.206). PIC mode effectively bypasses all APIC components and forces the system to operate in single processor mode. Note that APIC interrupts, including IPIs, do not work after this. Figure 14.29 Putting the motherboard back into PIC mode
Through 1999, Intel's competitors continued to use the Socket 7 design for CPU interface used in most Pentium CPUs. This meant that most competing CPUs used L2 caches on the motherboard rather than the CPU (the exception being AMD's K6-III), and these CPUs were limited to the 32-bit, 4GB memory address space of Pentiums. In terms of speed, though, some of these CPUs compete with CPUs through mid-range Pentium-IIIs. CPUs in this range include In addition to these CPUs that run in Socket 7 motherboards, AMD in 1999 introduced the Athlon, which uses a slot connector similar to (but incompatible with) the one used by Pentium-II and Pentium-III CPUs. The Athlon includes many advanced features, and competes directly against Pentium-III systems. In fact, in late 1999 and early 2000, the fastest x86 computers available were powered by Athlon CPUs. Like Intel's post-Pentium x86 CPUs, the Athlon includes an L2 cache on the CPU module and uses 36-bit memory addresses.
Since the appearance of the original IBM PC, keyboards have used 5-pin DIN connectors. On AT-style motherboards (described in Chapter 2, Motherboards ), the motherboard contains a connector for the 5-pin DIN keyboard plug. Some designs, however, have used a smaller mini-DIN connector, and this design has become standard with ATX and related motherboards. Because it was used on the IBM PS 2 computer, the mini-DIN design is sometimes referred to as a PS 2 keyboard port. Figure 15.2 shows both an older full-size 5-pin DIN connector (on the left) and an adapter that can be used to connect a full-size 5-pin DIN device into a newer mini-DIN motherboard. Despite their physical differences, keyboards that use the old full-size 5-pin DIN connectors and those that use the newer mini-DIN connectors are electrically compatible. An adapter like the one shown in Figure 15.2 is very simple in design it merely links connectors of differing sizes. You should therefore not be too concerned with the...
The general architecture of Trusted Computing (see Figure 12-1) revolves around a central component called the Trusted Platform Module (TPM), which is usually implemented as a separate secure chip integrated with the motherboard, but this integration is not a mandatory condition, and the TPM can also take alternative forms such as being a subcomponent of the chipset, a secure chip on a daughterboard, a software emulation, or a virtualized TPM. The TPM is a tamper-evident element that contains the RTS and the RTR, in addition to volatile and nonvolatile memory (and, in particular, a minimum of 16 Platform Configuration Registers (PCRs) that are used to store integrity measurements), cryptographic capabilities (secure hashing HMAC, RSA key generation and storage, RSA encryption and signature, and true random number generation), and opt-in commands in order to enable the use of TPM.
Is not enabled, Linux might not detect the floppy. If the BIOS configuration is correct and Linux can't use the floppy, it may be that the floppy controller is defective. As a device that's built into a motherboard, it can be difficult to replace a floppy controller, but old 486 and earlier systems often used floppy controllers on separate cards, so if you can find such an antique you may be able to make use of it. Parallel The parallel port is most commonly used for printers, but it can also handle some scanners, cameras, and external removable-media drives. Linux's parallel port support is mature, but it requires two drivers one for the low-level parallel port hardware and one for the device being driven. These drivers are included in all major Linux distributions' standard driver sets. Like many other motherboard-based ports, most BIOSes allow you to disable the parallel port, so you may want to check this detail if you're having problems. If necessary, you can buy an ISA or PCI...
Beginning in 1996, ATX motherboards became available. Intel developed the ATX specification, and has revised it several times. The broad outlines remain constant across ATX revisions, although some details have changed. ATX was designed to address several deficiencies in the AT and Baby AT form factors, such as Altered width depth ratio Baby AT designs are deeper than they are wide, forcing placement of CPUs or other components in line with the slots. This placement can limit options for the addition of large cards, particularly on CPUs like late-model Pentiums that require large heat sinks with fans. ATX motherboards, by contrast, are wider than they are deep. In an ATX design, the CPU goes to the side of the slots, as shown in Figure 2.1. Addition of external I O ports With motherboards universally deploying external I O ports, the ATX specification includes a standardized location for ports to be built into the motherboard, as shown in Figures 2.1 and 2.7. The keyboard uses a small...
When deciding on an x86 CPU, be sure your motherboard and CPU are matched. Most motherboards are designed to work with a narrow range of CPUs. You can't use a Pentium motherboard with a Pentium II CPU, for instance. Even within the realm of one CPU sub-class, there's substantial variability in compatibility. Some Pentium boards, for instance, only work with Pentium CPUs up to a certain clock speed, or might work with some clone CPUs but not others. Check the motherboard manufacturer's Web site for compatibility information.
The compute or processing nodes incorporate all hardware devices and mechanisms responsible for program execution, including performing the basic operations, holding the working data, providing persistent storage, and enabling external communications of intermediate results and user command interface. Five key components make up the compute node of a Beowulf cluster the microprocessor, main memory, the motherboard, secondary storage, and packaging. The motherboard is the medium of integration that combines all the components of a node into a single operational system. Far more than just a large printed circuit board, the motherboard incorporates a sophisticated chip set almost as complicated as the microprocessor itself. This chip set manages all the interfaces between components and controls the bus protocols. One important bus is PCI, the primary interface between the microprocessor and most high-speed external devices. Initially a 32-bit bus operating at 33 MHz, the most recent...
386 the four high-order bits of reason are cleared. These are read-only bits anyway. The four low-order bits are not affected. Bit 2 is set. This clears system board parity detection (bit 7) but leaves it disabled. The user has been warned that there is a problem we do not want to be overwhelmed with repetitions of the same interrupt.
Until recently, each generation of CPU (80386, 80486, and so on) has used a unique CPU motherboard interface method. These have generally come in the form of sockets, in which the CPU has a number of pins on its bottom that fit into a square connector on the O motherboard (see Figure 2.2). More recent CPUs, including most Pentium-II, Pentium-III, and H A socket on motherboards for socketed CPUs contains many holes into which the pins on the bottom of the CPU fit. A socket on motherboards for socketed CPUs contains many holes into which the pins on the bottom of the CPU fit. CPUs used. Early 80486 motherboards used sockets that required great force to insert the CPU, but later 80486 motherboards used zero insertion force (ZIF) sockets, in which a lever on one side of the socket allows you to tighten it around an inserted CPU. (This lever is visible to the right of the socket in Figure 2.2.) The vast majority of Pentium-class motherboards use ZIF sockets. Popular sockets for 80486 and...
Motherboard The main circuit board in a computer. The CPU, RAM, and add-on cards typically plug directly into the motherboard, although some designs place some of these components on extender cards. The motherboard is also sometimes referred to as the mainboard or the system board.
The TPM reset attack is technically very difficult to prevent using some of the oldest TPM technology, namely TPMs provided on daughterboards. The attack is more complicated to perform if the TPM is integrated to the motherboard, rendering access to the chip pins more difficult. On the other hand, the risk associated with this attack is very low due to the very high cost for the attacker She has to not only be present in front of the computer, but also open it, find the TPM and the correct pin, and put the wire at the
|ilmIT Computer Repair Manual||www.computerrepairebook.com|
The Ultimate Computer Repair Guide
Read how to maintain and repair any desktop and laptop computer. This Ebook has articles with photos and videos that show detailed step by step pc repair and maintenance procedures. There are many links to online videos that explain how you can build, maintain, speed up, clean, and repair your computer yourself. Put the money that you were going to pay the PC Tech in your own pocket.