Standard CMOS Setup

Remember young Jedi…

You should have your current setup options written down ON PAPER somewhere, preferably taped to the inside or the outside of the case. CMOS memory has a tendency to get erased as the battery gets old, or become inaccessible if you forget the password. Especially remember the hard disk settings; they are the most important.

If you have warm-booted the computer (via CTRL-ALT-DEL) to go into the CMOS setup, the BIOS routine to handle the "Print Screen" key will probably be installed. You can display each screen of the CMOS setup and press SHIFT-PRINT SCREEN to get a printed copy directly. There are several good CMOS saver programs out on the market, including the PC-Tools and Norton recovery programs. They allow a user to save a copy of the CMOS registers to a file in case the battery dies, or if they messed around with the settings, etc.

• Date (mn/date/year) and Time: To change the date and time of the system clock. Do not expect your computer to keep tract of time as accurately as an atomic clock, or even a wrist watch! Depending of the quality of the motherboard expect to loose (or gain) several seconds per month. On rare occasion you will need to setup the clock in BIOS Setting as all operating systems allow to change these settings within their environments.
• Daylight Saving: Allows the clock to automatically adapt to the daylight saving scheme which is removing one hour on the last Sunday of October and adding one hour on the last Sunday of April.
• Hard disk C type: The number of your primary (master) hard drive. Most of the time this number is 47, which means that you must specify the drive specs according to your hard drive manual.
  • Cyln: The number of cylinders on your hard disk.
  • Head: The number of heads.
  • WPcom: Write Precompensation. Older hard drives have the same number of sectors per track at the innermost tracks as at the outermost tracks. This means that the data density at the innermost tracks is higher and thus the bits are lying closer together. Starting with this Cyl# until the end of Cyl#s the writing starts earlier on the disk. In modern HDs such as SCSI (Small Computer Systems Interface) this entry is useless. Set it either to -1 or max Cyln (a common value is 65535). For IDE (Integrated Device Electronics) hard drives it is not necessary to enter a WP cylinder. The IDE HDD will ignore it for it has its own parameters inboard.
  • LZone: The address of the landing zone. Same as WPcom. Used in old HDs without an auto-parking feature (MFM, Modified Frequency Modulated, or RLL, Run Length Limited). Set it to 0 or max Cyl#.
  • Sect: The number of sectors per track. It is often 17 for MFM and 26 for RLL HDD. On other types of drives, it will vary.
  • Size : This is automatically calculated according the number of cylinders, heads and sectors. It is in megabytes and applies this formula: (Hds * Cyl * Sect * 512) / 1048.

EIDE specifications. With the growing capacity of hard disks on desktop computers, a redefinition of IDE specifications was necessary. The old IDE specification only supported drives up to 528 megabytes, which is the Normal partition setting. In 1994, the EIDE (Enhanced IDE) protocol was designed and now all new motherboards support it. This new protocol uses the LBA (Logic Block Addressing) system which considers logic blocks instead of heads, cylinders and sectors. If your BIOS does not support LBA, several hard disk manufacturers provide drivers to trick the BIOS. You will also find a Large partition setting that can accommodate drives up to 1024 cylinders, but do not support LBA. Unfortunately, many large implementations don't work correctly for drives of over 1GB (there's no good reason why it wouldn't work for much larger drives though). Note that 1024 cylinders native is 528MB. The 528MB limit is the 1024 cyl / 16 head / 63 sector limit. For more information about EIDE, please have a look at the EIDE FAQ.

• Hard disk D type: The number of your secondary (slave) hard drive. Same procedure than above. Jumpers must be set for an hard drive to perform as slave as well as master. Please refer to your hard drive manual for appopriate jumpers settings. You might also want to refer to the hard disk data file frequently posted to comp.sys.ibm.pc.hardware.storage.

Several of the PCI motherboards can now accommodate up to four IDE drives: Primary Master, Primary Slave, Secondary Master and Secondary Slave.

• Floppy drive A: The type of floppy drive installed for drive A. Frequent configurations are 1.44 MB (3 1/2 inches), or 1.2 MB (5 1/4). Newer systems have also a 2.88 MB (3 1/2) setting.
• Floppy drive B: The type of floppy drive installed for drive B.
• Primary display: The type of displaying standard you are using, and in case of systems with two video adapters the primary one. The most frequent is VGA/PGA/EGA. Modern computers have VGA (Video Graphics Array). If you have an older black/white display select Mono or Hercules, if your Video adapter card is text only, select MDA.
• Keyboard: Installed recommended. If "not installed" this option sets the BIOS to pass the keyboard test in the POST, allowing to reset a PC without a keyboard (file server, printer server, etc.), without the BIOS producing a keyboard error. As a system administrator, you can uninstall the keyboard as a supplementary security procedure to prevent people messing up with the server.