BIOS TEXT
BIOS
BIOS stands for Basic Input-Output System and is the low-level instructions used to communicate with the system devices. This is different than CMOS, which is simply an inventory list for the system, containing information such as the hard drive space and amount of memory that exist on the system. So, 180 The BIOS and Its Purpose CMOS is the inventory list while BIOS is the actual code that is run to communicate with those devices. Originally, the BIOS was stored in a ROM chip on the motherboard but because you had to replace the chip with a new chip to update the BIOS, today's systems have the BIOS code stored in an EEPROM chip located on the motherboard (for more information on ROM and EEPROM, check out the memory topic in Chapter 3 of this minibook). The chip that contains the BIOS code is known as the BIOS chip. The BIOS chip should be easy to find — it's usually rectangular and clearly labeled, normally with the name of the manufacturer of the BIOS chip and the date that the chip was created. In Figure 4-1, the BIOS chip is the chip with the white label indicated with a number 1.
Universal Serial Bus (USB)
Universal Serial Bus (USB) devices have gained much recognition over the last decade. USB devices are high-speed serial devices that use a single connector style and can be chained together with a USB hub device. A USB hub device connects all USB devices together at a central point. The USB hub may be its own unique device, or it may be just another device in the USB chain that has the capability of connecting other USB devices to it. For example, a USB monitor may have a USB port to allow a mouse to connect to it. Some popular USB-type devices include digital cameras, scanners, mice, and keyboards. You can even find USB network adapters. If you have any problems getting a USB device connected to your computer, make sure the USB port has been enabled in CMOS. Also, remember that you can disable the USB ports in CMOS (as shown in Figure 4-13) to help secure your environment. You may wish to do this to prevent a user on the network from using the flash drive to take proprietary corporate data home.
Upgrading the System BIOS
When your system was designed, its BIOS program code was designed to work with very specific devices. As you know, computer technology changes very quickly, almost overnight. So, what can you do if you have an older system and you want to update its capabilities? The BIOS dictates a system's capabilities. For example, assume that the BIOS on my old Pentium is only aware of an 8GB drive, but I would like to install a 12GB drive into the system. I must first upgrade the BIOS so that the system knows how to refer to a drive of that size. As far as the current BIOS is concerned, there is no such thing as a drive larger than 8GB — I need an upgraded BIOS to make the system understand! Another example of a good time to upgrade the BIOS code in hardware is with a wireless home router I purchased a few years back. I knew that I wanted to configure the wireless network to limit which MAC addresses (network cards) could connect to the wireless network. Unfortunately, there was no such setting in the configuration screens of the wireless router — so I went to the manufacturer's Web site and updated the BIOS in the router. After I completed the upgrade of the router, the setting I was looking for suddenly appeared on the configuration screens! The point is that it is extremely common to upgrade the BIOS on devices to make sure that the device is up to date with the current trends.
Reserve resources
resources Many systems let you reserve resources that have been assigned to legacy devices in CMOS. Legacy devices are non-Plug and Play devices, such as ISA (Industry Standard Architecture) cards, that have been added to the system. The ISA non-Plug and Play devices are hard coded with a particular I/O address and IRQ, so you may need to configure CMOS to reserve the IRQ so that it is not given to a Plug and Play device on startup. Removing the IRQ will ensure that a Plug and Play system will not assign the resources that are hard-coded into older devices to Plug and Play devices, which would create a conflict. Most systems today are Plug and Play, so, unless you're supporting older hardware, you will most likely not hit this issue. Figure 4-16 shows how to reserve a resource in CMOS by setting the resource to "ISA" — meaning it is being used by an ISA device, so the system is not to give this resource out to another device. Now it is time to get some hands-on by performing Lab 4-1 and Lab 4-2! Lab 4-1 and Lab 4-2 can be found in the Labs.pdf file in the Author directory of the CD-ROM.
VIEWING CMOS SETTINGS
Boot sequence Take special note of the CMOS entry for boot sequence; it determines what devices the system will try to boot off of and in what order it tries each device. For example, older systems are typically set up to boot off a floppy disk first, and if a bootable floppy disk isn't present, the system then boots off the hard drive. Newer systems let you boot off a CD-ROM device or even off the network first and then, if no bootable device is found in either of those spots, proceed to boot off the hard drive. Booting off a CD-ROM makes installing an operating system extremely easy because most operating systems today (like Windows or Linux) support booting off the installation CD to install the operating system. Most systems today are configured to try to boot from a floppy disk, then a CD-ROM, then a hard disk, and finally a network. You determine the order to suit your needs, although typically, the floppy or CD-ROM drive is checked before the hard drive. If you like, you can disable devices, such as a CD-ROM drive — from being bootable. This is an important point because system security can be bypassed if a hacker can boot off his own CD containing his own copy of an operating system. For security reasons, your company may consider disabling booting from floppy disk or CD-ROM. Figure 4-10 shows the CMOS menu where you can configure the startup order for your system's devices.
CMOS ADVICE
CMOS information is held in CMOS RAM, which is volatile memory that is able to maintain its data during shutdowns or power loss by using a small battery located on the motherboard. Thus, if the battery on the motherboard loses power, the CMOS data is also lost. Figure 4-3 shows a CMOS battery on a system board. The CMOS configuration is stored in CMOS RAM. Because RAM loses its contents when the system is powered off, the motherboard has a small battery that maintains enough of a charge that CMOS RAM can maintain its data — thus allowing the system to retain the CMOS information between reboots.
Understanding CMOS
Complementary Metal-Oxide Semiconductor (CMOS) contains the computer's inventory list and advanced setup options. It can be considered an inventory list because it contains a record of all the devices connected to the system, such as the floppy drive, the hard drive, memory, and so on. Not only does CMOS list the devices, but it also dictates their capacity — for example, whether the system has a 2GB or a 6GB hard drive. During the boot process, the system compares its inventory list to what it detects during boot-up. If there are any discrepancies, the system typically gives you an error and takes you into CMOS right away, asking you to save the new change. For example, assume that your system has 512MB of RAM and you add another 512MB of RAM to it. When you power the system up, the system compares what it had in inventory (512MB) the last time it booted with what it sees now (1024MB). Because there is a difference, CMOS reports a memory size error and gives you the opportunity to save the new changes to CMOS. CMOS doesn't know that the difference is for the better; if it sees a difference, it reports an error. Because CMOS has detected the new memory, all you have to do is save the changes to the inventory list and reboot. Looking at the previous example, if you choose not to save the settings you will get the memory size the next time you start the computer. In order to prevent the error from appearing again you will save the changes to CMOS — this way the values that are detected are equal to what is stored in CMOS. Before discussing the different CMOS settings, it's important to know how to enter the CMOS setup program. Figuring this out is difficult on some systems, but extremely easy on others. Some systems display a message on boot-up that indicates what keystroke (often Delete or F1) to use to enter the CMOS setup program. IBM systems typically use the F1 key (refer to Figure 4-2); Dell systems today typically use F2 or the delete key. Compaq systems typically use the F10 keystroke. In many Compaq systems, pressing F10 when you see a squared cursor in the top-right corner of the computer screen when the system starts up lets you enter the CMOS program. In some older systems, you enter CMOS by holding down multiple keys at the same time during boot-up — Ctrl+Alt+S or Ctrl+Alt+Insert, for example. Entering into these systems is a little trickier, so reviewing your documentation is helpful. (Note that it has been a long time since I have seen a system that uses these three-key combinations to enter the CMOS setup program.) Table 4-1 summarizes popular keystrokes used to enter CMOS based off the manufacturer of the BIOS. (Remember that the CMOS setup program is stored in BIOS.)
VIEWING CMOS SETTINGS
Date and time The date and time each have an entry in CMOS as well, which is where the operating system gets its date and time information. If you set the date and time in CMOS it will set the date and time for the operating system. From a troubleshooting point of view, you know that your CMOS battery is dying when, during startup, the system asks you for the date and time. During startup after a battery failure, all of the other settings are detected again — which is why you don't specify the hard disk or the floppy disk. However, the date and time must be specified again.
VIEWING BASIC CMOS SETTINGS
Floppy disk drive One option in CMOS lets you enable or disable the floppy disk drive. When the disk drive is enabled, its size is also specified and can usually be changed. If the disk drive is enabled but the wrong size disk drive is specified, you may not be able to access a floppy disk that has been placed in the drive. CMOS allows you to disable devices such as disk drives and USB ports so that companies can keep employees from copying proprietary data. Figure 4-6 shows the menu setting that allows you to change the size of the disk drive and even disable the disk drive. Memory
Viewing Advanced CMOS Settings
Globally Unique Identifier (GUID) The Globally Unique Identifier (GUID) is a 128-bit number randomly generated for the system when it was built and is stored in CMOS. The GUID uniquely identifies the system from any other. It enables the identification of individual computers and ensures that this identification method is 100-percent unique. Many features in today's computers make use of the GUID. For example, one of the Windows installation tools (Remote Installation Services, or RIS) allows the administrator to go into a client computer's CMOS, make a note of the GUID, create a computer account within Windows Active Directory database for the workstation, and associate the GUID with the account. If the client computer is booting off the network when it starts, it will contact the RIS server and start installing a Windows client operating system. The client computer will use the computer name of the computer account found in Windows Active Directory that its GUID is associated with. Some systems have adopted the term UUID (Universally Unique Identifier) instead of GUID. Remember, you may see a UUID in CMOS instead of a GUID, as shown in Figure 4-12, but they're the same thing.
Viewing Basic CMOS Settings
Hard drive Within the CMOS setup program you will be able to find out the size of the hard drive. CMOS displays the size of the hard drive based on what was detected during startup. The hard drive size is displayed in CMOS, as shown in Figure 4-5. On some older systems you could change the CMOS from autodetect to manual so that you can specify the dimensions of the drive — overriding what was detected. Specifying the dimensions of the drive involves looking on the back of the drive to find out how many sectors, cylinders, and heads the drive contains — which dictates the size of the drive. When you know the dimensions, you can input these dimensions into CMOS (after switching from autodetect to manual). CMOS calculates the size of the drive based on the dimensions you input.On older systems, you specify the hard drive size by specifying a drive type. The drive type is a number representing a drive of a specific size. For example, a Type 2 drive may be 1.2GB in size, while a Type 10 drive may be 1.5GB in size (the actual values of hard drive types vary from system to system and are usually displayed along with the type). There is also a custom type on Figure 4-5: Viewing the hard drive size in CMOS. Figure 4-4: A typical CMOS screen. older systems, usually Type 47, which enables you to specify the dimensions of the drive (sectors, cylinders, heads); CMOS can then calculate the size in megabytes for you after you input the dimensions.
Potential issues with BIOS upgrading
If you decide to perform a BIOS upgrade, consider these few words of caution: ✦ Be sure you're applying the correct BIOS update for system. You want to make sure that you are aware of who the manufacturer is for your BIOS before you look for an update. Once you know the manufacturer of your BIOS you can go to the manufacturer's Web site and download the update. You will not be able to mix BIOS codes between manufacturers — for example, you cannot update your Compaq system with a BIOS update from Dell. ✦ Be sure that you not only have the BIOS update for the correct system, but also that the BIOS update you have is designed for your version of the BIOS. Each BIOS has a revision number or version number. The developers of the BIOS update program may place a version check into the BIOS update, but you cannot be sure of that. So as a result, be sure to double-check that the BIOS update you are running is for the BIOS version you have. Installing the wrong BIOS version can cause the system to become dysfunctional. If you can't find a BIOS version number, use the BIOS date to decide which update to download — either one should be located within CMOS or displayed with the BIOS manufacturer on the screen during boot-up, as shown in Figure 4-2. ✦ When you start a BIOS update, be sure that you complete it. Rewriting only a portion of the BIOS code (whether as a result of an accidental shutdown or power loss during the writing process) can cause the system to become dysfunctional. The actual BIOS update should take only a few seconds, so try not to disrupt the BIOS update after it starts.
On-board cache
In Book II, Chapter 3, I discuss the benefits of cache and the types of cache memory, L1 and L2. In CMOS, you typically find an entry indicating how much cache memory exists on the system, and you can configure CMOS to disable this built-in cache memory. Sometimes cache memory goes bad and causes boot-up problems. If having cache memory enabled presents any compatibility problems with your system, you can try disabling the cache memory as a troubleshooting technique. Figure 4-15 shows the size of the cache memory and the option to enable or disable the cache memory. If the problem doesn't go away, then there was no problem with the cache memory to begin with; enable the cache memory once again.
Performing the BIOS upgrade
In the past, with older systems, you would upgrade the BIOS by completely replacing the BIOS chip. Back then, BIOS was stored on a ROM (Read-Only Memory) chip, which could not be written to. In order to "rewrite" the code, you needed to replace the entire chip! Today's systems use a modified version of the ROM chip — an EEPROM (Electronically Erasable Programmable Read-Only Memory) chip. To upgrade the program code on an EEPROM chip, you don't need to physically replace the chip; you just run a software program that was designed to rewrite the program code. To upgrade the BIOS, you need to get the update program from the manufacturer. You can usually find the program on the manufacturer's Web site (and it's usually downloadable), or you may be able to order a CD from the manufacturer. Be sure to follow the manufacturer's directions on how to apply the update to your BIOS. 182 Upgrading the System BIOS For example, a popular technique of updating a BIOS is to download the BIOS update program from the manufacturer's Web site to a floppy disk. After you download the BIOS program to a floppy disk, you boot off the floppy disk and the update starts. Just follow the directions on the screen. The update program rewrites the program code stored in the BIOS chip that is normally read-only. Because you are writing to this ROM chip with a special program, they call the ROM a flash ROM, where flashing is the process of rewriting the program code. Today's computer systems are no longer shipping with built-in floppy drives so it is up to the manufacturer of the BIOS to decide how the BIOS update will be performed. If the manufacturer still requires you to use a floppy disk then you can purchase a USB floppy drive to connect to a system when you do the update. Some manufacturers may allow you to perform a BIOS update by running the update program from CD-ROM after downloading it.
VIEWING BASIC CMOS SETTINGS
Memory CMOS indicates the total amount of memory installed on the system. Typically, this entry is not modified unless you add or remove RAM and the change is detected on boot-up. If you do add or remove RAM from the system, the system detects the change and modifies CMOS for you. All you need to do is save the modification once in the CMOS setup program. Some systems today inform you that the system has saved the change for you and don't require you to enter the CMOS setup program. Figure 4-7 shows the CMOS System Summary screen, which shows that there are 640MB of system memory installed on the system. The CMOS in some systems not only tells you how much memory you have installed but also informs you of the type of memory that is installed. These systems usually allow you to change the type of memory if the system supports different types of memory (for example, FPM, EDO, SDRAM, DDR; see Book II, Chapter 3 for more on memory types). For example, I have an old Pentium that supports either FPM or EDO memory, and CMOS displays the memory type being used.
Built-in network adapter
Most systems today come with built-in network cards that allow the system to connect to a network or the Internet. Because the card is built-in, you don't have to buy a network card for the system. However, built-in network cards (or any built-in device) sometimes become faulty, but your system doesn't know that and always tries to use this built-in device anyway. Note that you can usually enable or disable the built-in network card through the CMOS setup program. When your system includes a built-in network adapter, you usually have the option of enabling or disabling the capability to boot off the network as well. Unless this option is enabled, you will not be able to boot off the network — even if you have specified a network boot in your startup order. You need to verify three options in CMOS in order to boot off the network: verify that the network card is enabled, verify that your system has enabled booting off the network adapter, and then ensure that the network device is located in the startup order of devices. To boot off the network, you probably want the network as the first boot device.
VIEWING CMOS SETTINGS
Parallel ports CMOS offers the opportunity to configure your parallel port. This configuration allows you to either disable the port or change the mode the port runs in. You might think that a parallel port doesn't require a lot of configuration, but think about this: Have you ever had problems with a scanner that plugs into your parallel port? Or more specifically, have you ever had problems with your parallel-port scanner plugging into your computer and the printer then connecting to your scanner? The problems may derive from the parallel port mode being misconfigured on the system. The parallel port mode dictates the capabilities of the parallel port. Table 4-2 lists the three parallel port modes that can be configured for your system.If you're having trouble daisy-chaining the scanner and printer off the parallel port on the computer, check to make sure that the proper port mode is selected in the CMOS setup program (shown in Figure 4-8) — in this example, you want to make sure that EPP is selected because it supports daisy-chaining. Daisy-chaining is the feature of connecting one device off another, such as connecting the printer to the scanner and the scanner to the LPT port.The resources of the parallel port may also need to be configured if there are conflicts with another device. Notice that the default IRQ for LPT1 is 7, and the default I/O address is 378-37F. You will learn about IRQs and I/O addresses in Book III, Chapter 4 — for now, just make a mental note that you can configure the IRQ and I/O address of the parallel port in CMOS.
VIEWING CMOS SETTINGS
Passwords In general, two types of passwords can be set in CMOS: the power-on password and the administrator password. The steps to set the password are different per manufacturer but you will usually find the password option under a security menu in the CMOS setup program. The power-on password is required in order to power the computer on. It is part of the power-on process and occurs before the operating system is loaded. Many people like to call it a hardware password because the operating system (the software) won't have a chance to load unless the correct password is typed in. The implementation of power-on passwords may be especially useful in environments in which security is a significant issue. You set the administrator password in the CMOS setup program. This password is required for anyone wishing to enter the CMOS setup program and make changes to the system configuration. It prevents unauthorized users from entering the CMOS setup program and changing the values that reside there. When people get comfortable with computers, they start to explore the computer's options. Companies often end up spending time and money fixing problems that arise from the exploration of these options. It may be useful to set an administrator password — that is, a password someone has to supply before entering CMOS to make changes. While the administrator password enables you to secure the workstation at the administrative level, the poweron password allows you to secure the system at the user level — controlling who can use the system. A question I often receive is, "What happens if you forget the CMOS password after it is set?" The answer is simple. First, check to see if the motherboard has a jumper that can be removed to make CMOS forget the passwords (see Figure 4-11). Once you remove the jumper to clear the password you put the jumper back on and power on the computer. Some systems will have you place the jumper over specific pins in order to clear the password — check the documentation to find out how to clear the password for your particular system. If no such feature exists on your motherboard, you could remove the CMOS battery from the motherboard. Remember that CMOS RAM retains its information because there is a battery supplying power to the memory where CMOS data is stored. If you remove the battery, CMOS is erased, including the passwords (it's better than throwing the system away!). The only problem with removing the battery is that all the CMOS information is lost — including your hard drive, memory, and other device settings. The good news is that most of the information should be detected again on startup, such as the amount of memory installed or the size of the hard drive. Earlier in this chapter, I mention that if your system asks you for the date and time when it boots up, this is usually an indication that your CMOS battery is dead or dying. As noted here, the date and time aren't the only things lost to a dying battery. If security is an issue, and if your system keeps asking you for the date and time at boot-up, replace the battery immediately and then reset the administrator password to keep others, malicious or benign, from altering the CMOS setup. A third solution to a forgotten password — and the one I like — is to get a CMOS utility, such as the CMOS Save &Restore utility. CMOS Save & Restore backs up the CMOS information and then allows you to restore it when an emergency arises. This solution involves backing up CMOS before a password is set, so that CMOS can be restored to a state without a password. These utilities are popular ones that can be found on the Internet, and they back up the CMOS information to a text file. An example of a CMOS save and restore program can be found at http://mindprod.com/products1.html#CMOSSV.
VIEWING CMOS SETTINGS
Plug and Play BIOS Most systems today have a Plug and Play BIOS (PnP BIOS). The term Plug and Play refers to the idea that you can connect a new device to the system and the system automatically detects and configures the device to work with your system. To have a Plug and Play system, three conditions are necessary: ✦ You need a Plug and Play device. ✦ You need a Plug and Play operating system. ✦ You need a Plug and Play BIOS. If you're missing any one of these conditions, the operating system will not be able to leverage Plug and Play and assign resources to a device on startup. On some older systems you may see an entry in CMOS stating that it is a Plug and Play BIOS. All newer systems are Plug and Play BIOSes.
vIEWING CMOS SETTINGS
Serial ports A typical system includes two serial ports, known as COM1 and COM2, and CMOS should have an entry for each of the serial ports — these entries enable you to change the resources, such as the IRQ (Interrupt ReQuest) and I/O address used by each of the serial ports, as shown in Figure 4-9. The CMOS shown in Figure 4-9 identifies the two serial ports as serial port A and serial port B. Be sure to remember that the default IRQ for COM1 is 4, and the default IRQ for COM2 is 3. The default I/O address for COM1 is 3F8-3FF, and the default I/O address for COM2 is 2F8-2FF. In the CMOS setup program, you will not only find an option to change the resources for the serial ports, but you will also be able to disable the serial ports. Disabling the serial ports involves entering your CMOS program and switching a serial port to the disabled setting.
VIRUS PROTECTION
Some BIOS systems have built-in virus protection — which is, for the most part, a good thing. Some viruses attack the system by altering the Master Boot Record (MBR). The MBR is the code that initiates the startup of the system and is located at the beginning of the hard drive. For more information on MBR and hard drives, check out the next chapter in this minibook. The virus protection built into the BIOS watches out solely for changes to the MBR and puts a stop to it!
BIOS date and revision number
The date of your BIOS should be displayed somewhere in CMOS, usually under Summary Information. If you don't have a BIOS date, you may have a revision number or level. These entries in CMOS are important because you may be required to update your BIOS someday by going to the manufacturer's Web site and downloading the update. The first thing you will notice when doing this is that the manufacturer has built many different versions of BIOS for its systems. You need to make sure you get the proper update (the one for the date of your BIOS) by watching the revision number of your BIOS. For example, the site may tell you to download BIOS update "1234" if you have Revision number R5.145. The big question is how do you know what your revision number is? Check CMOS! Refer again to Figure 4-12. You can see the BIOS version, or revision number, identified by the label "Flash EEPROM Revision Level." To ensure that you have downloaded the correct BIOS update for the system it is always a good idea to make a note of the revision number and the date of the existing BIOS. Both pieces of information are typically used to determine which BIOS you need to download from the manufacturer's Web site.
bIOS MORE
Along with the low-level code, the BIOS also contains the POST (Power-On Self-Test) and the CMOS setup program. The POST is a self-diagnostics routine that the system goes through each time it boots up. This self-diagnostic checks to see that each device listed in CMOS actually exists on the system. The POST also tests devices, such as I/O ports and memory, to verify that they not only exist but also that they still function. You use the CMOS setup program, stored in the BIOS, to navigate through the CMOS settings — but the BIOS does not contain the settings themselves. As you find out in the section, "Understanding CMOS," later in this chapter, the CMOS settings are maintained in CMOS RAM.
BIOS ADVICE
As a way to prevent accidental writing to the BIOS code, some motherboards ship with a jumper on the board that must be removed in order to write to the BIOS chip. When you decide that you want to upgrade the BIOS, and you have downloaded the correct BIOS update, you remove the jumper and then run the BIOS update. After updating the BIOS you place the jumper back. Now that you have an understanding of what the BIOS is used for and how to update the BIOS, it's time to move on to CMOS and the different computer settings that can be controlled through CMOS.
