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-
- The AMI BIOS Survival Guide v3.1
- Edited by Jean-Paul Rodrigue
- rodriguj@mistral.ere.umontreal.ca
-
- Contributors
- ==================================
- Gordon L. Burditt (gordon@sneaky.lonestar.org)
- Peter Herweijer (pieterh@sci.kun.nl)
- Kajetan Hinner (uf341ea@sunmail.lrz-muenchen.de)
- Piotr Karocki (yskarock@cyf-kr.edu.pl)
- Brian Lee (blee@bart.conestogac.on.ca)
- Aad Offerman (offerman@einstein.et.tudelft.nl)
- Keith Rohrer (rohrer@fncrd8.fnal.gov)
- Jerome Schneider (jls@atg.com)
- Cameron Spitzer (cls@truffula.sj.ca.us)
- Andy Walton (akw@ukc.ac.uk)
-
- Version history
- ==================================
- Version 1.0 to 1.3: December 1993 (initial postings)
- Version 2.0 to 2.4: January 1994 (the first "complete" versions)
- Version 2.5 and 2.6 : February 1994 (vitamin C added)
- Version 2.65 and 2.7: March 1994 (no cholesterol)
- Version 3.0: 16-04-94 (new prune-strawberry-cabbage flavour)
- Version 3.1: 13-05-94 (friday the 13th edition)
-
- What's new in version 3.1 (*)
- ==================================
- - FTP archive site available for the guide.
- - A list of BIOS error messages (see section 2.4)
- - Several additions to various topics (*).
-
- Crossposted in:
- ==================================
- comp.sys.ibm.pc.hardware, comp.sys.ibm.pc.hardware.chips,
- comp.sys.ibm.pc.hardware.misc & comp.answers (patent pending).
-
- (*) Archive Site
- ==================================
- The guide, along with other hardware-related FAQs, is available through
- anonymous FTP at rahul.net in the pub/cameron/PC-info directory. The
- document is compressed by Gzip, available at any GNU archive sites like
- gatekeeper.dec.com, in the pub/GNU directory.
-
- What is the AMI BIOS survival guide?
- ==================================
- BIOS settings are a frequent problem in several hardware related newsgroups.
- Did you ever experienced a system lock up or poor performance and erratic
- behaviour due to improper BIOS settings? Have you ever been let in the dark by
- a cryptic 5 pages badly written motherboard manual? The answer is probably
- yes. I took some initiative and decided to edit a FAQ for the AMI BIOS
- (American Megatrends Inc.). This BIOS is, I believe, the most common. The
- guide provides a description of each BIOS functions (at least those we are
- aware of) and tips for their settings. I hope it will eventually help newbies
- "decipher" BIOS settings and more advanced users "optimize" their system. It
- could even keep you from a painful visit to your local computer store!
-
- Disclaimer and other stuff
- ==================================
- This document is provided "as is". The editor and contributors take no
- responsabilities for any problems, damages, humiliations, world wars or loss
- of sanity resulting from improper BIOS settings. If you are in doubt, please
- post a question to the comp.sys.ibm.pc.hardware.chips newsgroup or refer to a
- competent computer technician. Messing up with something you do not
- understand will often get you in trouble (Who doesn't know someone who did?).
- YOU HAVE BEEN WARNED.
-
- This guide is provided as a free reference for the usenet (internet)
- community. You may distribute it freely as long as the contents are not
- altered, no fees are asked, and references to the editor and contributors are
- kept. If you are making money out of this file or posting net-wide (to groups
- where it does not belong) religious babblings or green card lottery scam: may
- your CPU perish by electromigration!
-
- I want to know more...
- ==================================
- If you have an UNSOLVED BIOS problem not described herein, please post it to
- related newsgroups (like comp.sys.ibm.pc.hardware.chips), NOT to the editor or
- the contributors. You should also have a look at the ibm.pc.hardware.*
- Frequently Asked Questions (FTP rtfm.mit.edu; directory:
- /pub/usenet/news.answers/csiph-faq; filenames: part1 to part5) posted
- regularly. It contains a wealth of information about computer hardware. Look
- also in the comp.answers newsgroup for available FAQs.
-
- If you have a SOLVED problem, please send it to the editor so it can be added
- to subsequent versions of this document. Your contributions or comments will
- be much appreciated. If you want the most recent version of this document,
- please e-mail the editor and tell what version you currently have. If a more
- recent version is available, it will be fowarded. Before doing so, please look
- in this newsgroup for a regular posting of this guide.
-
- If you want various technical information about AMI BIOS, you can find it at
- the FTP site AMERICAN.MEGATRENDS.COM. If you can afford long distance
- charges, try the AMI BBS at (404) 246-8780 (or 8781, 8782, 8783). There is
- also a shareware named AMISETUP that enables BIOS settings and provides an
- on-line reference (for registered versions). It can even let you access some
- settings that could not be accessed otherwise. You can find it at SIMTEL
- mirror sites like FTP.WUSTL.EDU or OAK.OAKLAND.EDU in the
- /systems/ibmpc/msdos/sysutil directory. The file name is AMISE260.ZIP.
-
- One last thing...
- ==================================
- I would like to thank the contributors to have taken some of their time to
- write varied topics and provide enlightening feedbacks. Some parts of this
- document are still incomplete and some information may be inaccurate. Your
- feedbacks will help this document be as accurate and up to date as possible. I
- am sorry if I cannot answer to everyone or add everything that is send to me.
-
- I would also like to thank the following persons for providing information on
- specific topics: Michiel de Vries, Andy Eskilsson, Doug Hogarth, Reinhard
- Kirchner, Mirek Komon, Jim Kozma, Juha Laiho, Alain Lavoie, Erik Mouw, Chris
- Pollard, Dietrich Schmidt, Hans Schrader, Loren Schwiebert, Dan Sobel, Dave
- Spensley and Dmitry Stefankov.
-
- TABLE OF CONTENT
- ==================================
-
- 1.0 DEFINITIONS
- 1.1 BIOS
- 1.2 CMOS
- 1.3 Chipset
-
- 2.0 POST AND ENTERING SETUP
- 2.1 A Typical AMI BIOS POST Sequence
- 2.2 AMI BIOS POST Errors
- 2.3 Other AMI BIOS POST Codes
- (*) 2.4 BIOS Error Messages
-
- 3.0 STANDARD CMOS SETUP
-
- 4.0 ADVANCED CMOS SETUP
-
- 5.0 ADVANCED CHIPSET SETUP
-
- 6.0 AUTO CONFIGURATION WITH BIOS DEFAULTS
-
- 7.0 AUTO CONFIGURATION WITH POWER-ON DEFAULTS
-
- 8.0 CHANGE PASSWORD
-
- 9.0 HARD DISK UTILITY
- 9.1 Hard Disk Format
- 9.2 Auto Detect Hard Disk
- 9.3 Auto Interleave
- 9.4 Media Analysis.
-
- 10.0 WRITE TO CMOS AND EXIT
-
- 11.0 DO NOT WRITE TO CMOS AND EXIT
-
- 12.0 FREQUENTLY ASKED QUESTIONS (FAQ)
-
- 1.0 DEFINITIONS
- ==================================
-
- 1.1 BIOS: Basic Input Output System. Computer hardware has to work with
- software, so it needs an interface with it. The BIOS gives the computer a
- little built-in starter kit to run the rest of softwares from floppy disks
- (FDD) and hard disks (HDD). The BIOS is responsible for booting the computer
- by providing a basic set of instructions. It performs all the tasks that need
- to be done at start-up time: POST (Power-On Self Test, booting an operating
- system from FDD or HDD). Furthermore, it provides an interface to the
- underlying hardware for the operating system in the form of a library of
- interrupt handlers. For instance, each time a key is pressed, the CPU
- (Central Processing Unit) perform an interrupt to read that key. This is
- similar for other input/output devices (Serial and parallel ports, video
- cards, sound cards, hard disk controllers, etc...). Some older PC's cannot
- co-operate with all the modern hardware because their BIOS doesn't support
- that hardware. The operating system cannot call a BIOS routine to use it;
- this problem can be solved by replacing your BIOS with an newer one, that does
- support your new hardware, or by installing a device driver for the hardware.
-
- 1.2 CMOS: Complementary Metal Oxide Semiconductor. To perform its tasks, the
- BIOS need to know various parameters (hardware configuration). These are
- permanently saved in a little piece (64 bytes) of CMOS RAM (short: CMOS). The
- CMOS power is supplied by a little battery, so its contents will not be lost
- after the PC is turned off. Therefore, there is a battery and a small RAM
- memory on board, which never (should...) loses its information. The memory
- was in earlier times a part of the clock chip, now it's part of such a highly
- Integrated Circuit (IC). CMOS is the name of a technology which needs very
- low power, so the computer's battery is not too much in use. Actually there
- is not a battery on new boards, but an accumulator (Ni_Cad in most cases). It
- is recharged every time the computer is turned on. If your CMOS is powered by
- external batteries, be sure that they are in good operating condition. Also,
- be sure that they do not leak. It may damage the motherboard. Otherwise,
- your CMOS may suddenly "forget" its configuration and you may be looking for a
- problem elsewhere. In the monolithic PC and PC/XT this information is
- supplied by setting the DIP (Dual-In-line Package) switches at the motherboard
- or peripheral cards. Some new motherboards have a technology named the Dallas
- Nov-Ram. It eliminates having an on-board battery: There is a 10 year lithium
- cell epoxyed into the chip.
-
- 1.3 Chipset: A PC consists of different functional parts on its motherboard:
- ISA (Industry Standard Architecture), EISA (Enhanced Industry Standard
- Architecture) VESA (Video Enhanced Standards Association) and PCI (Peripheral
- Component Interface) slots, memory, cache memory, keyboard plug etc... The
- chipset enables a set of instructions so the CPU can work (communicate) with
- other parts of the motherboard. Nowadays most of the discrete chips; PIC
- (Programmable Interrupt Controller), DMA (Direct Memory Access), MMU (Memory
- Management Unit), cache, etc... are packed together on one, two or three
- chips; the chipset. SETUP allows you to change the parameters with which the
- BIOS configures your chipset. Since chipsets of a different brand are not the
- same, for every chipset there is a BIOS version. Now we have fewer and fewer
- chipsets which do the job. Some chipsets have more features, some less. OPTi
- is such a commonly used chipset. In some well integrated motherboards, the
- only components present are the CPU, the two BIOS chips (BIOS and Keyboard
- BIOS), one chipset IC, cache memory (DRAMs, Dynamic Random Access Memory),
- memory (SIMMs, Single Inline Memory Module, most of the time) and a clock
- chip.
-
- 2.0 POST AND ENTERING SETUP
- ==================================
- When the system is powered on, the BIOS will perform diagnostics and
- initialize system components, including the video system. (This is
- self-evident when the screen first flicks before the Video Card header is
- displayed). This is commonly refered as POST (Power-On Self Test). Afterwards,
- the computer will proceed its final boot-up stage by calling the operating
- system. Just before that, the user may interupt to have access to SETUP.
-
- To allow the user to alter the CMOS settings, the BIOS provides a little
- program, SETUP. Mostly setup can be entered by pressing a special key
- combination (DEL, ESC, CTRL-ESC, or CRTL-ALT-ESC) at boot time (Some BIOSes
- allow you to enter setup at any time by pressing CTRL-ALT-ESC). The AMI BIOS
- is mostly entered by pressing the DEL key after resetting (CTRL-ALT-DEL) or
- powering up the computer. You can bypass the extended CMOS settings by
- holding the <INS> key down during boot-up. This is really helpful, especially
- if you bend the CMOS settings right out of shape and the computer won't boot
- properly anymore. This is also a handy tip for people who play with the older
- AMI BIOSes with the XCMOS setup. It allows changes directly to the chip
- registers with very little technical explanation.
-
- 2.1 A Typical AMI BIOS POST Sequence
- ------------------------------
-
- a) Display some basic informations about the video card like its brand, video
- BIOS version and video memory available.
-
- b) Display the BIOS version and copyright notice in upper middle screen. You
- will see a large sequence of numbers at the bottom of the screen. They refer
- to the BIOS serial number, version and type of chipset. (*) For versions
- 1986-1991 (AMIBIOS before HI-Flesh):
-
- Reference number: ABBB-NNNN-MMDDYY-KX, where
-
- A = D for BIOS with Diagnostics.
- = S for BIOS with Setup program.
- = E for BIOS with Extended Setup program.
- BBB = C&T for C&T386 chipset.
- = NET for C&T NEAT chipset.
- = 286 fpr standard 286,VLSI,G2 286 boards.
- = SUN for SUNTAC 286 boards.
- = PAQ for COMPAQ compatible 386 boards.
- = INT for INTEL boards.
- = AMI for AMI 386 motherboard.
- = G23 for G2 386 board.
- = ??? other n/a.
- NNNN = reference number for manufacturer.
- MMDDYY = BIOS release date.
- KX = AMI keyboard BIOS version number (X = usually
- 1,2,3,etc).
- (could someone provide information for recent BIOS serial numbers?)
-
- c) Display memory count. You will also ear tick sounds if you have enabled it
- (see Memory Test Tick Sound section).
-
- d) Once the POST have succeeded and the BIOS is ready to call the operating
- system (DOS, OS/2, NT etc...) you will see a basic table of the system's
- configurations:
-
- Main Processor: The type of CPU identified by the BIOS. Usually
- Cx386DX, Cx486DX, etc..
-
- Numeric Processor: Present if you have a FPU or None on the contrary. If
- you have a FPU and the BIOS does not recognize it,
- see section Numeric Processor Test in Advanced CMOS
- Setup.
-
- Floppy Drive A: The drive A type. See section Floppy drive A in
- Standard CMOS Setup to alter this setting.
-
- Floppy Drive B: Idem.
-
- Display Type: See section Primary display in Standard CMOS Setup.
-
- AMIBIOS Date: The revision date of your AMI BIOS. Useful to mention
- when you have compatibility problems with adaptor
- cards (notably fancy ones).
-
- Base Memory Size: The number of KB of base memory. Usually 640.
-
- Ext. Memory Size: The number of KB of extended memory.
-
- NOTE: In the majority of cases, the summation of base memory and extended
- memory does not equal the total system memory. For instance in a 4096 KB
- (4MB) system, you will have 640KB of base memory and 3072KB of extended
- memory, a total of 3712KB. The missing 384KB is reserved by the BIOS, mainly
- as shadow memory (see Advanced CMOS Setup).
-
- Hard Disk C: Type: The master HDD number. See Hard disk C: type section
- in Standard CMOS Setup.
-
- Hard Disk D: Type: The slave HDD number. See Hard disk D: type section
- in Standard CMOS Setup.
-
- Serial Port(s): The hex numbers of your COM ports. 3F8 and 2F8 for
- COM1 and COM2.
-
- Parallel Port(s): The hex number of your LTP ports. 378 for LPT1.
-
- Right under the table, BIOS usually display the size of cache memory. Common
- sizes are 64KB, 128KB or 256KB. See External Cache Memory section in Advanced
- CMOS Setup.
-
- 2.2 AMI BIOS POST Errors
- ------------------------------
- During the POST routines, which are performed each time the system is powered
- on, errors may occur. Non-fatal errors are those which, in most cases, allow
- the system to continue the boot up process. The error messages normally
- appear on the screen. Fatal errors are those which will not allow the system
- to continue the boot-up procedure. If a fatal error occurs, you should
- consult with your system manufacturer or dealer for possible repairs. These
- errors are usually communicated through a series of audible beeps. The
- numbers on the fatal error list correspond to the number of beeps for the
- corresponding error. All errors listed, with the exception of #8, are fatal
- errors. All errors found by the BIOS will be put into I/O port 80h.
-
- # of Beeps Meaning
-
- 1 DRAM refresh failure. The memory refresh circuitry on
- the motherboard is faulty.
-
- 2 Parity Circuit failure. A parity error was detected in the
- base memory (first 64k Block) of the system.
-
- 3 Base 64K RAM failure. A memory failure occured
- within the first 64k of memory.
-
- 4 System Timer failure. Timer #1 on the system board has
- failed to function properly.
-
- 5 Processor failure. The CPU on the system board has
- generated an error.
-
- 6 Keyboard Controller 8042-Gate A20 error. The
- keyboard controller (8042) contains the gate A20 switch
- which allows the computer to operate in virtual mode.
- This error message means that the BIOS is not able to
- switch the CPU into protected mode.
-
- 7 Virtual Mode (processor) Exception error. The CPU on
- the motherboard has generated an Interrupt Failure
- exception interrupt.
-
- 8 Display Memory R/W Test failure. The system video
- adapter is either missing or Read/Write Error its memory
- is faulty. This in not a fatal error.
-
- 9 ROM-BIOS Checksum failure. The ROM checksum
- value does not match the value encoded in the BIOS.
- This is good indication that the BIOS ROMs went bad.
-
- 10 CMOS Shutdown Register. The shutdown register for the
- CMOS memory Read/Write Error has failed.
-
- (*)11 Cache Error / External Cache Bad. The external cache
- is faulty.
-
- 2.3 Other AMI BIOS POST Codes
- ------------------------------
- 2 short beeps: POST failed. This is caused by a failure of one of the
- hardware testing procedures.
-
- 1 long & 2 short
- beeps: Video failure. This is caused by one of two possible
- hardware faults. 1) Video BIOS ROM failure,
- checksum error encountered. 2) The video adapter
- installed has a horizontal retrace failure.
-
- 1 long & 3 short
- beeps: Video failure. This is caused by one of three possible
- hardware problems. 1) The video DAC has failed. 2)
- the monitor detection process has failed. 3) The video
- RAM has failed.
-
- 1 long beep: POST passed. This indicates that all hardware tests
- were completed without encountering errors.
-
- If you have access to a POST Card reader, (Jameco, etc) you can watch the
- system perform each test by the value that's displayed. If/when the system
- hangs (if there's a problem) the last value displayed will give you a good
- idea where and what went wrong, or what's bad on the system board. Of course,
- having a description of those codes would be helpful, and different BIOSes
- have different meanings for the codes. (could someone point out FTP sites
- where we could have access to a complete list of error codes for different
- versions of AMI BIOS?).
-
- (*)2.4 BIOS Error Messages
- ------------------------------
- This is a short list of most frequent on-screen BIOS error messages. Your
- system may show them in a different manner. When you see any of these,
- you are in trouble - Doh! (Does someone has any additions of
- corrections?)
-
- "8042 Gate - A20 Error" : Gate A20 on the keyboard controller
- (8042) is not working.
-
- "Address Line Short!" : Error in the address decoding circuitry.
-
- "Cache Memory Bad,
- Do Not Enable Cache!" : Cache memory is defective.
-
- "CH-2 Timer Error" : There is an error in timer 2. Several
- systems have two timers.
-
- "CMOS Battery State Low" : The battery power is getting low. It
- would be a good idea to replace the battery.
-
- "CMOS Checksum Failure" : After CMOS RAM values are saved, a
- checksum value is generated for error
- checking. The previous value is different
- from the current value.
-
- "CMOS System Options
- Not Set" : The values stored in CMOS RAM are
- either corrupt or nonexistent.
-
- "CMOS Display Type
- Mismatch" : The video type in CMOS RAM is not the
- one detected by the BIOS.
-
- "CMOS Memory Size
- Mismatch" : The physical amount of memory on the
- motherboard is different than the amount in
- CMOS RAM.
-
- "CMOS Time and Date
- Not Set" : Self evident.
-
- "Diskette Boot Failure" : The boot disk in floppy drive A: is corrupt
- (virus?). Is an operating system present?
-
- "Display Switch Not
- Proper" : A video switch on the motherboard must
- be set to either color or monochrome.
-
- "DMA Error" : Error in the DMA controller.
-
- "DMA #1 Error" : Error in the first DMA channel.
-
- "DMA #2 Error" : Error in the second DMA channel.
-
- "FDD Controller Failure" : The BIOS cannot communicate with the
- floppy disk drive controller.
-
- "HDD Controller Failure" : The BIOS cannot communicate with the
- hard disk drive controller.
-
- "INTR #1 Error" : Interrupt channel 1 failed POST.
-
- "INTR #2 Error" : Interrupt channel 2 failed POST.
-
- "Keyboard Error" : There is a timing problem with the
- keyboard.
-
- "KB/Interface Error" : There is an error in the keyboard
- connector.
-
- "Parity Error ????" : Parity error in system memory at an
- unknown address.
-
- "Memory Parity Error
- at xxxxx": : Memory failed at the xxxxx address.
-
- "I/O Card Parity Error
- at xxxxx": An expansion card failed at the xxxxx
- address.
-
- "DMA Bus Time-out" : A device has used the bus signal for more
- than allocated time (around 8
- microseconds).
-
- NOTE: If you encounter any POST error, there is a good chance that it is an
- HARDWARE related problem. You should at least verify if adaptor cards or
- other removable components (simms, drams etc...) are properly inserted before
- calling for help.
-
- 3.0 STANDARD CMOS SETUP
- ==================================
- WARNING: 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.
-
- NOTE: 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 they mess around
- with the settings, etc...
-
- Date (mn/date/year) : To change the date of the system clock.
-
- Time (hour/min/sec) : To change the time of the system clock.
-
- 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 HDD's have the same
- number of sectors per track at the innermost tracks as at the
- outhermost tracks. This means that the data density at the
- innermost tracks is higher and thus the bits are lying closer
- together. Normally the data is written like this:
- + + - + - + + + - - - +
- Areas having the same direction tend to float away from
- eachother and areas having opposite direction tend to float
- towards eachother:
- + + - + - + + + - - - +
- making the data less reliable after some time. To avoid this,
- starting from the WP cylinder, bits are written on the surface
- like this:
- + + - + - + + + - - - +
- making your data last longer. Starting with this Cyl# until
- the end of Cyl#s the writing starts earlier on the disk. In
- modern HDs (all AT-BUS and SCSI, Small Computer Systems
- Interface) this entry is useless. Set it either to -1 or max
- Cyln. For IDE (Integrated Device Electronics) HDD's it is not
- necessary to enter a WP cylinder. The IDE HDD will ignore it
- for it has its own parameters aboard.
-
- 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.
-
- Size : This is automatically calculated according the number
- of cylinders, heads and sectors. It is in megabytes.
-
- NOTE: There is a shareware program called ANYDRIVE that will allow you to set
- up hard drive geometries not supported in your BIOS. This should be available
- on your favourite local BBS (Any internet FTP site for this one?). Note that
- it only sets the correct geometry, many older BIOSes have timing problems with
- IDE drives and this type of problem will not be helped by ANYDRIVE. (*) You
- can also use the freeware program HD-MBOOT from the archive file DSUTIL12.ZIP
- on the Internet: SIMTEL20 or its mirrors, and GARBO FTP-sites in the directory
- /MSDOS/TURBOPAS or PC/TURBOPAS.
-
- 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. Please refer to your hard drive manual. You
- might also want to refer to the hard disk data file frequently
- posted to comp.sys.ibm.pc.hardware.
-
- 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. 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. 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.
-
- 4.0 ADVANCED CMOS SETUP
- ==================================
- WARNING: May vary according to your system and your BIOS version. Some
- functions may not be present or the order and name may be different.
-
- ADDITIONAL WARNING: Know *exactly* what you are doing. Some configurations
- may keep your computer off from booting. If that's the case: Switch the power
- off. Turn your computer on *while* keeping the DEL key pressed. Some
- mainboards will come up again. If it still doesn't boot, consult your
- motherboard manual. Look for a "forget CMOS RAM" jumper. Set it. Try it
- again. If it still doesn't boot, ask a friend or post to this newsgroup. You
- are permitted to panic. See note in section 3.0.
-
- Typematic Rate
- Programming : Disabled. It enables the typematic rate
- programming of the keyboard. Not all keyboards
- support this! The following two entries specify how
- the keyboard is programmed if enabled.
-
- Typematic Rate Delay
- (msec) : 500. The initial delay before key auto-repeat
- starts. I.e. how long you've got to press a key
- before it starts repeating.
-
- Typematic Rate (Chars/Sec) : 15. It is the frequency of the auto-repeat
- i.e. how fast a key repeats.
-
- Above 1 MB Memory Test : If you want the system to check the memory above 1
- MB for errors. Disabled recommended for faster boot
- sequence. The HIMEM.SYS driver for DOS 6.2 now
- verifies the XMS (Extended Memory Specification), so
- this test is redundant. Alternatively, you can enable
- this test and disable HIMEM.SYS from doing so. (*) It
- is preferrable to use the XMS test provided by
- HIMEM.SYS since it is operating in the real
- environment (where user wait states and other are
- operational).
-
- Memory Test Tick Sound : Enabled recommended. It gives an audio record that
- the boot sequence is working properly. Plus, its
- aural confirmation of your CPU clock speed/Turbo
- switch setting (for trained users!).
-
- Memory Parity Error
- Check : Enabled recommended. Additional feature to test bit errors
- in the memory. All (or almost all) PC's check their memory
- during operation. Every byte in memory has another ninth bit,
- that with every write access is set in such way that the parity
- of all bytes is odd. With every read access the parity of a
- byte is checked for this odd parity. If a parity error occurs,
- the NMI (Non Maskable Interrupt), an interrupt you mostly
- cannot switch off, so the computer stops his work and displays
- a RAM failure) becomes active and forces the CPU to enter an
- interrupt handler, mostly writing something likes this on the
- screen: PARITY ERROR AT 0AB5:00BE SYSTEM HALTED. On some
- motherboards you can disable parity checking with standard
- memory. Enabled to be sure data from memory are correct.
- Disable only if you have 8-bit RAM, which some vendors use
- because it's 10% cheaper. If you own a Gravis Ultrasound
- Soundcard (GUS), it's imperative that this is enabled;
- otherwise the Sound Blaster emulation won't work(!).
-
- Hard Disk Type 47
- RAM Area : The BIOS has to place the HD type 47 data somewhere in memory.
- You can choose between DOS memory or PC BIOS (or peripheral card)
- memory area 0:300. DOS memory is valuable, you only have 640KB of
- it. So you should try to use 0:300 memory area instead. There may
- be some peripheral card which needs this area too (soundcard,
- network, whatever). So if there are some fancy cards in your PC,
- check the manuals if they're using the 0:300 area. But in most
- cases this will work without checking. (*) This is redundant if BIOS
- is shadowed (may be not in very old BIOSes). The RAM area can be
- verified by checking address of int41h and int46h. These are fixed
- disk parameters blocks. If they point to the BIOS area, BIOS made
- modification of parameters before mapping RAM there.
-
- Wait for <F1> If
- Any Error : When the boot sequence encounter an error it asks you to press F1.
- Only at 'non-fatal' errors. If disabled, system print warning and
- continues to boot without waiting for you to press any keys. Enabled
- recommended.
-
- System Boot Up Num
- Lock : Specify if you want the Num Lock key to be activated at
- boot up. Some like it, some do not. MS-DOS (starting with
- 6.0, maybe earlier) allows a "NUMLOCK=" directive in
- config.sys, too; if someone turns the BIOS flag off but
- has NUMLOCK=ON in their configuration file, they may be a
- bit perturbed.
-
- Numeric Processor
- Test : Enabled if you have a math coprocessor (built in for the
- 486DX and 486DX2 family). Disabled if you don't (386SX,
- 386DX, 486SX, 486SLC and 486DLC). If disabled, your FPU
- (Floating Point Unit, if present) isn't recognized as
- present by the system.
-
- Weitek Coprocessor : If you have Weitek FPU, enable. If you haven't,
- disable. Weitek uses some RAM address space, so memory
- from this region must be remapped somewhere else.
-
- Floppy Drive Seek at Boot : Power up your A: floppy drive at boot.
- Disabled recommended for faster boot sequence
- and for reduced damage of heads.
-
- System Boot
- Sequence : What drive the system checks first for an operating system.
- C:, A: recommended for faster boot sequence, or to not allow
- any user to enter your system by booting from the FDD if your
- autoexec.bat starts with a login procedure. A:, C: if the
- person who uses the computer is someone who don't knows how to
- setup CMOS. Because if something fails and a boot floppy won't
- work, many users won't know what to do next. However, be
- careful. You had better know this setting is turned on and be
- prepared to turn it off if your hard disk boot track becomes
- corrupted, but not obviously absent, since you otherwise won't
- be able to boot from floppy. Also, it's easy to fool yourself
- into thinking you booted from a known virus-free floppy when it
- actually booted from the (virus-infested) hard drive.
-
- System Boot Up
- CPU speed : Specify at what processor speed the system will boot from. Usual
- settings are HIGH and LOW. HIGH recommended. If you encounter
- booting problems, you may try LOW.
-
- External Cache
- Memory : Enabled if you have cache memory. This is a frequent error
- in CMOS setup. If Disabled when you have cache memory, the
- system performance decreases significantly. Most systems have
- from 64 to 256KB of external cache. It is a cache between the
- CPU and the system bus. If Enabled when the system does not
- have cache memory, the system will freeze most of the time.
-
- Internal Cache
- Memory : Enable or disable the internal cache memory of the CPU.
- Disabled for 386 and Enabled for 486 (1 to 8KB of internal CPU
- cache). If the CPU does not have internal cache, the system
- may freeze if enabled.
-
- NOTE: In many AMI BIOSes, the two previous options are implemented either as
- separate Internal and External Enable/Disable options, or as a single option
- (Cache Memory : Disabled/Internal/Both).
-
- Fast Gate A20 Option : A20 refers to the first 64KB of extented memory (A0
- to A19) known as the "high memory area". This option
- uses the fast gate A20 line, supported in some
- chipsets, to access memory above 1 MB. Normally all
- RAM access above 1 MB is handled through the keyboard
- controller chip. Using this option will make the
- access faster than the normal method. This option is
- very useful in networking operating systems.
-
- Shadow Memory
- Cacheable : You increase speed by copying ROM to RAM. Do you want to
- increase it by cacheing it? Yes or no - see Video BIOS
- Area cacheable. Yes recommended.
-
- Password Checking
- Option : Setup password to have access to the system and / or to
- the setup menu. Good if the computer is to be shared with
- several persons and you don't want anyone (friends, sister
- etc...) to mess up with the BIOS. Default password: AMI
- (if you have AMI BIOS). Award: BIOSTAR (Note: I even know
- a computer store that kept standard award BIOS
- configuration with their systems because they didn't know
- what the award default password was!).
-
- Video ROM Shadow
- C000,16K : Memory hidden under the "I/O hole" from 0x0A0000 to 0x0FFFFF
- may be used to "shadow" ROM (Read- Only Memory). Doing so, the
- contents of the ROM are copied into the RAM and the RAM is used
- instead. Video BIOS is stored in slow EPROM (Erasable
- Programmable Read-Only Memory) chips (120 to 150ns of access
- time). Also, ROM is 8 or 16 bit while RAM 32 bit wide access.
- With Shadow on, the EPROM content is copied to RAM (60 to 80ns
- of access time with 32 bit wide access). Therefore perfomance
- increases significantly. Only sensible on EGA/VGA systems.
- Enabled recommended. If you have flash BIOS, you can disabled
- it. Flash BIOS enable access at speeds similar to memory
- access so you can use the memory elsewhere. However, flash
- BIOS is still only accessing it at the speed of the bus (ISA,
- EISA or VLB). On systems where the BIOS automatically steals
- 384k of RAM anyway, it shouldn't hurt to enable shadowing even
- on flash ROM. One side effect is that you will not be able to
- modify the contents of flash ROM when the chip is shadowed. If
- you reconfigure an adapter which you think might have flash
- ROM, and your changes are ignored, or of course if it gives you
- an error message when you try to change them, you'll need to
- temporarily disable shadowing that adapter. On (S)VGA you
- should enable both video shadows. Some video cards maybe using
- different addresses than C000 and C400. If it is the case, you
- should use supplied utilities that will shadow the video BIOS,
- in which case you should disable this setting in the CMOS.
- Video BIOS shadowing can cause software like XFree86 (the free
- X Window System) to hang. They should be probably be disabled
- if you run any of the 386 unixes.
-
- NOTE: Some cards map BIOS or other memory not only in the usual
- a0000-fffff address range, but also just below the 16MB border or at other
- places. The BIOS (for PCI buses only?) now allows to create a hole in the
- address range where the card sits. The hole may be enabled by giving an
- address, then a size is requested in power of 2, 64k - 1MB.
-
- Video ROM Shadow C400,16K : Same than previous, except it is for another
- segment of video memory. Enabled recommended.
-
- Adaptor ROM Shadow
- C800,16K : Disabled. Those addresses (C800 to EC00) are for
- special cards, e.g. network and controllers. Enable only
- if you've got an adapter card with ROM in one of these
- areas. It is a BAD idea to use shadow RAM for memory
- areas that aren't really ROM, e.g. network card buffers
- and other memory-mapped devices. This may interfere with
- the card's operation. To intelligently set these options
- you need to know what cards use what addresses. Most
- secondary display cards (like MDA and Hercules) use the
- ROM C800 address. Since they are slow, shadowing this
- address would improve their performance. An advanced tip:
- in some setups it is possible to enable shadow RAM
- *without* write-protecting it; with a small driver (UMM)
- it is then possible to use this 'shadow RAM' as UMB (Upper
- Memory Block) space. This has speed advantages over UMB
- space provided by EMM386.
-
- Adaptor ROM Shadow CC00,16K : Disabled. Some hard drive adapters use that
- address.
-
- Adaptor ROM Shadow D000,16K : Disabled. D000 is the default Address for
- most Network Interface Cards.
-
- Adaptor ROM Shadow D400,16K : Disabled. Some special controllers for four
- floppy drives have a BIOS ROM at D400..D7FF.
-
- Adaptor ROM Shadow D800,16K : Disabled
-
- Adaptor ROM Shadow DC00,16K : Disabled
-
- Adaptor ROM Shadow E000,16K : Disabled. E000 is a good "out of the way"
- place to put the EMS page frame. If necessary.
-
- Adaptor ROM Shadow E400,16K : Disabled
-
- Adaptor ROM Shadow E800,16K : Disabled
-
- Adaptor ROM Shadow EC00,16K : Disabled. SCSI controller cards with their
- own BIOS could be accalerated by using Shadow
- RAM. Some SCSI controllers do have some RAM
- areas too, so it depends on the brand.
-
- NOTE: Some SCSI adapters do not use I/O-Adresses. The BIOS address range
- contains writable addresses, which in fact are the I/O-ports. This means:
- this address must not be shadowed and even not be cached.
-
- System ROM Shadow F000,64K : Same thing as Video shadow, but according to
- the system bios (main computer BIOS). Enabled
- recommended for improved performance. System
- BIOS shadowing and caching should be disabled to
- run anything but MSDOS.
-
- NOTE: On some BIOS versions (probably newer ones) the shadow choices are in
- 800(hex)-byte increments. For instance, instead of two Video ROM Shadow
- segments of 16K (C400 and C800), you will have one 32K segment. Same thing
- for Adaptor ROM Shadow segments.
-
- BootSector Virus
- Protection : It is not exacly a virus protection. All it does is
- whenever your boot sector is accessed for writing, it
- gives a warning to the screen allowing you to disable the
- access or to continue. Extremely annoying if you use
- something like OS/2 Boot Manager that needs to write to
- it. It is completely useless for SCSI or ESDI (Enhanced
- Small Device Interface) drives as they use their own BIOS
- on the controller. Disabled recommended. If you want
- virus protection, use a TSR (Terminate and Stay Resident)
- virus detection (Norton, Central Point, etc...). Scan by
- Macfee is also a good idea. Available on most FTP
- servers, it is a shareware.
-
- 5.0 ADVANCED CHIPSET SETUP
- ==================================
- WARNING: May vary according to your system and your BIOS version. Be sure of
- what you are doing!
-
- Hidden Refresh : Allows the RAM refresh memory cycles to take place in memory
- banks not used by your CPU at this time, instead or together
- with the normal refresh cycles, which are executed every time a
- certain interrupt (DRQ0 every 15 msecs) is called by a certain
- timer (OUT1). Every time it takes 2 to 4 msecs for the
- refresh. One refresh cycle every ~16 us refreshes 256 rows in
- ~ 4ms. Each refresh cycle only takes the equivalent of one
- memory read or less, as CAS (Column Address Strobe) is not
- needed for a refresh cycle. Some RAMs can do it, some not.
- Try. If the computer fails, turn it off. Enabled recommended.
- There are typically 3 types of refresh schemes: cycle steal,
- cycle stretch, or hidden refresh. Cycle steal actually steals
- a clock cycle from the CPU to do the refresh. Cycle stretch
- actually delays a cycle from the processor to do the refresh.
- Since it only occurs every say 4ms or so, it's an improvement
- from cycle steal. We're not really stealing a cycle, only
- stretching one. Hidden refresh typically doesn't stretch or
- steal anything. It's usually tied to DTACK (Data acknowledge)
- or ALE (Address Latch Enable) or some other signal relating to
- memory access. Since memory is accessed ALL of the time, ie
- ram, rom, etc. it's easy to synchronize the the refresh on the
- falling edge of this event. Of course, the system performance
- is at its optimum efficiency, refresh wise sinces we're not
- taking clock cycles away from the CPU.
-
- Slow Refresh : Causes RAM refresh to happen less often than usual. This
- increases the performance slightly due to the reduced
- contention between the CPU and refresh circuitry, but not all
- DRAMs necessarily support these reduced refresh rates (in which
- case you will get parity errors and crashes).
-
- Concurrent Refresh : Both the processor and the refresh hardware have acces
- to the memory at the same time. If you switch this off,
- the processor has to wait until the refresh hardware has
- finished (it's a lot slower). Enabled recommended.
-
- Single ALE Enable : ALE (Address Latch Enable) is a pin on your PC-bus that
- is active each time there is an address on the bus. May
- slow the video bus speed is enabled. Still very
- obscure???
-
- Keyboard Reset Control : Enable Ctrl-Alt-Del warm reboot. Enabled
- recommended for more control over your system.
-
- AT BUS Clock
- Selection : Gives a division of the CPU clock so it can reach the ISA - EISA
- bus clock. An improper setting may cause significant decrease in
- performance. The settings are in terms of CLK/x, (or CLKIN/x) where
- x may have values like 2, 3, 4, 5, etc. CLK represents your
- processor speed, with the exception that clock-multiple processors
- need to use the EXTERNAL clock rate, so a 486DX33, 486DX2/66, and
- 486DX3/99 all count as 33. You should try to reach 8.33 Mhz (that's
- the old bus clock of IBM AT; there may be cards which could do
- higher, but it's not highly recommended). On some motherboards, the
- AT bus speed is 7.15 Mhz. On new BIOS versions, there is an AUTO
- setting that will look at the clock frequency and determine the
- proper divider.
-
- CPU Speed Appropriate setting
- 16 CLK/2
- 25 or DX2/50 CLK/3
- 33, DX2/66 or DX3/99 CLK/4
- 40 or DX2/80 CLK/5
- 50 or DX2/100 CLK/6
-
- You can try other settings to increase performance. If you choose a
- too small divider (CLK/2 for a DX33) your system may hang. For a too
- big divider (CLK/5 for a DX33) the performance of ISA cards will
- decrease. This setting is for data exchange with ISA cards, NOT VESA
- cards which run at CPU bus clock speeds: 25Mhz, 33Mhz and higher. If
- your ISA cards are fast enough to keep up, it is possible to run the
- bus at 12 Mhz. Note that if you switch crystals to overclock your
- CPU, you are also overclocking the ISA bus unless you change
- settings to compensate. Just because you can overclock the CPU
- doesn't mean you can get away with overclocking the ISA bus. It
- might just be one card that causes trouble, but one is enough. It
- might cause trouble even if you aren't using it by responding when
- it shouldn't.
-
- Fast AT Cycle : If enabled, may speed up transfer rates with ISA cards,
- notably video. ???
-
- Fast Decode
- Enable : Refers to some hardware that monitors the commands sent to the
- keyboard controller chip. The original AT used special codes not
- processed by the keyboard itself to control the switching of the 286
- processor back from protected mode to real mode. The 286 had no
- hardware to do this, so they actually have to reset the CPU to
- switch back. This was not a speedy operation in the original AT,
- since IBM never expected that an OS might need to jump back and
- forth between real and protected modes. Clone makers added a few
- PLD chips to monitor the commands sent to the keyboard controller
- chip, and when the "reset CPU" code was seen, the PLD chips did an
- immediate reset, rather than waiting for the keyboard controller
- chip to poll its input, recognize the reset code, and then shut down
- the CPU for a short period. This "fast decode" of the keyboard
- reset command allowed OS/2 and Windows to switch between real and
- protected mode faster, and gave much better performance. (early 286
- clones with Phoenix 286 BIOS had this setting to enable/disable the
- fast decode logic.) On 386 and newer processors, the fast decode is
- probably not used, since these CPUs have hardware instructions for
- switching between modes. There is another possible definition of
- the "Fast Decode Enable" command. The design of the original AT bus
- made it very difficult to mix 8-bit and 16-bit RAM or ROM within the
- same 128K block of high address space. Thus, an 8-bit BIOS ROM on a
- VGA card forced all other peripherals using the C000-Dfff range to
- also use 8 bits. By doing an "early decode" of the high address
- lines along with the 8/16 bit select flag, the I/O bus could then
- use mixed 8 and 16 bit peripherals. It is possible that on later
- systems, this BIOS flag controls the "fast decode" on these address
- lines.
-
- Extended I/O Decode : The normal range of I/O addresses is 0-0x3ff; 10 bits of
- I/O address space. Extended I/O-decode enables wider
- I/O-address bus. The CPU(s) support a 64K I/O space, 16
- address lines. Most motherboards or I/O adapters can be
- decoded only by 10 address bits.
-
- (*)I/O Recovery Time : When enabled, more I/O wait states are inserted. A
- transfer from IDE harddrive to memory happens without
- any handshaking, meaning the data has to be present
- (in the cache of the harddisk) when the CPU wants to
- read them from an I/O Port. This is called PIO
- (Programmed I/O) and works with a REP INSW assembler
- instruction. Now I/O Recovery Time enabled adds some
- wait states to this instruction. When disabled, the
- harddrive is a lot faster. Note that there is a
- connection between I/O Recovery Time and AT BUS Clock
- Selection. For example, if the AT BUS Clock is set
- to 8 MHZ and you have a normal harddisk, I/O Recovery
- Time can be turned off, resulting in a higher
- transfer rate from harddisk.
-
- Memory Read
- Wait State : Wait states is for RAM which aren't fast enough for the
- computer. On a 486, 1 or more wait states are often
- required for RAM with 80ns or higher access time. And,
- depending on the processor and motherboard, also for lower
- than 80ns access time. The less wait states, the better.
- Consult your manual. If wait states are too low, a parity
- error will occur. For 386 or 486 non-burst memory access
- cycle takes 2 clock ticks. A *rough* indication of RAM
- speed necessary for 0 wait states is 2000/Clock[MHz] - 10
- [ns]. For a 33Mhz processor, this would give 50ns of
- access time required. The number of wait states necessary
- is *approximately* (RamSpeed[ns] +10) * Clock[MHz] /1000 -
- 2. For 70ns RAM and a 33Mhz processor (very standard
- configuration), this would give roughly 1 wait state. But
- this really is dependent on chipset, motherboard and cache
- design, CPU type and whether we talk about reads or
- writes. Take these formulas with a large grain of salt.
- You can find out the access time of your RAM chips by
- looking at their product numbers. Mostly at the end there
- is a 70, 80, 90, or even 60. If 10 stands there, it means
- 100 ns. Some RAM chips also have an explicitly written
- speed in ns. The RAM you buy these days mostly have 70ns
- or 60ns.
-
- Memory Write Wait State : Same as above.
-
- Note: In some BIOSes, these two options are combined as 'DRAM Wait State'. In
- that case, the number of read & write wait states is necessarily equal.
-
- Post Write Control : ???
-
- CAS Pulse Width : Column Address Strobe. A DRAM parameter.
- ???
-
- RAS Precharge Time : Row Address Strobe. ???
-
- RAS to CAS Delay : ???
-
- Cache Read Option : Often also "SRAM Read wait state", (SRAM: Static Random
- Access Memory) taking simple integer values, or "SRAM
- Burst", taking 2-1-1-1, 3-1-1-1 or 3-2-2-2. This
- determines the number of wait states for the cache RAM in
- normal and burst transfers (the latter for 486 only). The
- lower you computer can support, the better.
-
- Cache Write Option : Same thing as memory wait states, but according to cache
- ram.
-
- Non-Cacheable
- Block-1 Size : Disabled. The Non-Cacheable region is intended for a
- memory-mapped I/O device that isn't supposed to be cached. For
- example, some video cards can present all video memory at 15
- meg - 16 meg so software doesn't have to bank-switch. If the
- non-cacheable region covers actual RAM memory you are using,
- expect a significant performance decrease for accesses to that
- area. If the non-cacheable region covers only non-existent
- memory addresses, don't worry about it. If you dont want to
- cache some memory you can exclude 2 regions of memory. There
- are *good* reasons not to cache some memory areas. For
- example, if the memory area corresponds to some kind of buffer
- memory on a card so that the card may alter the contents of
- this buffer without warning the cache to invalidate the
- corresponding cache lines. Some BIOSes take more options than
- enabled /disabled, namely Nonlocal /Noncache /Disabled (VLB
- only?).
-
- Non-Cacheable Block-1 Base : 0KB. Enter the base address of the area you
- don't want to cache.
-
- Non-Cacheable Block-2 Size : Disabled.
-
- Non-Cacheable Block-2 Base : 0KB.
-
- Cacheable RAM
- Address Range : Usually chipsets allow memory to be cached just up to 16 or
- 32 MB. This is to limit the number of bits of a memory address
- that need to be saved in the cache together with its contents.
- If you only have 4MB of RAM, select 4MB here. The lower the
- better, don't enter 16MB if you only have 8MB installed!
-
- Video BIOS Area
- Cacheable : To cache or not to cache video BIOS. You should try what is
- better - video access is faster with 'enabled', but cache has
- its size. With an "accelerated" video card it may be necessary
- to make the video RAM region non-cacheable so the CPU can see
- any changes the drawing engine makes in the frame buffer.
-
- 6.0 AUTO CONFIGURATION WITH BIOS DEFAULTS
- ==================================
- The BIOS defaults are the ones that are tuned for your motherboard/chipset,
- but give a reasonable chance of getting into POST. Usually these settings are
- a good start to fine tune your system. If you did something wrong and don't
- know what, select this. It will replace your BIOS settings by default values.
- You will have to start all over again. Be sure to know your system's
- configuration. This option does *not* alter the date and harddisk & floppy
- disk configuration in the Standard CMOS setup, so in general you can expect
- your system to boot without problems after selecting this.
-
- 7.0 AUTO CONFIGURATION WITH POWER-ON DEFAULTS
- ==================================
- When powering on, the BIOS puts the system in the most conservative state you
- can think of. Turbo off, all caches disabled, all wait states to maximum,
- etc... This is to make sure that you can always enter BIOS setup. Useful if
- the settings obtained by selecting AUTO CONFIGURATION WITH BIOS DEFAULTS fail.
- If the system does not work with these values, it's time to panic: the problem
- maybe hardware related (DIP switches, cards not inserted properly or worst,
- something broken).
-
- 8.0 CHANGE PASSWORD
- ==================================
- Enable you to change the active password. The default is no password.
- WARNING: Remember your password!!! Write it down somewhere!!! Ask yourself: Do
- I really need to set a password to access my system and/or the BIOS? (is your
- brother/sister/kid/employee that dangerous?) If security is of some minor
- concern to you, disabled recommended. Why not only password protect (or
- encrypt) some critical files (personal finances, juicy love letters, client
- information databases, etc...)? If you lose your password, you will have to
- erase your CMOS memory (see FAQ).
-
- 9.0 HARD DISK UTILITY
- ==================================
-
- 9.1 Hard Disk Format
- ------------------------------
- Will format your hard disk so it can receive new partitions. WARNING: IT WILL
- SMASH EVERYTHING ON YOUR HARD DISK!!! USE WITH CAUTION. A lot of
- inexperienced users have lost their sanity with this one. Several computer
- stores have made extra money with it! There's no need to do this unless you
- experience errors or if you want to change the interleave. DON'T TOUCH THIS
- IF YOU'VE GOT AN IDE DRIVE. It will perform a low level format and probably
- SCRAP your IDE hard drive. IDE means AT-Bus, the standard drive type nearly
- everyone has now. Also SCSI or ESDI drives shouldn't be low-level formatted.
- The new drives actually don't perform the low level format, but some old
- AT-Bus (IDE) drives you can scratch with this... This entry is only sensible
- for old MFM or RLL hard disks! Please refer to your hard disk manual to see
- how or if your hard disk can be low level formatted. Don't tell us we did not
- warn you.
-
- Many manufacturers provide utilities to low level format their IDE drives (or
- any other types). Please refer to the comp.sys.ibm.pc.hardware.storage FAQ
- for more technical information about this procedure. If normal (high level)
- hard disk formatting is required, you can use DOS FDISK to first erase and
- create partitions and then use FORMAT. It is also a good idea when you hard
- disk becomes unaccessible to see if it is just the system files that are
- corrupted. Most of the time, it is the case. SYS will do the job of
- replacing system files. Several packages (PC-Tools, Norton, etc...) provide
- utilities for repairing "damaged" HDD and FDD. Therefore, low level format is
- always of LAST RESORT when you encounter HDD problems.
-
- 9.2 Auto Detect Hard Disk
- ------------------------------
- Handy when you "forgot" the specs of your hard drive. The BIOS will detect
- the number of cylinders, heads and sectors on your hard disk.
-
- NOTE: In some BIOS versions, this option in the main SETUP menu.
-
- 9.3 Auto Interleave
- ------------------------------
- Determines the optimum interleave factor for older hard disks. Some
- controllers are faster than others, and you don't want the sectors laid out so
- reading consecutive sectors usually results in just missing the sector you
- wanted and having to wait a whole disk rotation for it to come around again.
- On modern ones, it's always 1:1 (and even if it wasn't, you cannot reformat
- anyway).
-
- Interleaving is specified in a ratio, n:1, for small positive integers n.
- Basically, it means that the next sector on the track is located n positions
- after the current sector. The idea is that data on a hard drive might spin
- past the heads faster than the adapter can feed it to the host. If it takes
- you more than a certain amount of time to read a sector, by the time you're
- ready for the next sector, the heads will have passed it already. If this is
- the case, the interleave is said to be "too tight". The converse, where the
- CPU spends more time than necessary waiting for the next sector to spin under
- the heads, is too "loose" of an interleave. Clearly, it is better to have too
- loose an interleave than too tight, but the proper interleave is better still.
- Especially since any controller with read-ahead cacheing can pull the whole
- track into its buffer, no matter how slow the CPU is about fetching the data
- down.
-
- The 1:1 interleave arranges the sectors on a track as follows:
- 0 1 2 3 4 5 6 7 8 9 a b c d e f g (17-sectors, using base 17 for
- convenience, this is clearly the in-order arrangement, one after another)
-
- This is 2:1 interleaving:
- 0 9 1 a 2 b 3 c 4 d 5 e 6 f 7 g 8
-
- The CPU has a whole sector's worth of time to get the a sector's data taken
- care of before the next sector arrives. It shows which logical sector goes in
- each physical sector.
-
- Anyway, an n:1 interleave restricts the transfer rate to 1/n the speed of a
- 1:1 interleave (which is better than 1 revolution per sector if the interleave
- is too tight!). No modern PC should require interleaving. Only MFM and RLL
- (maybe also ESDI) and floppy drives which are capable of it (you could format
- a 1.44 meg floppy to 21 sectors/track, which would require a 2:1 interleave to
- not exceed the 500 mbps speed of the controller...but why?).
-
- 9.4 Media Analysis.
- ------------------------------
- Scan the hard disk for bad blocks. It is performing a LOW LEVEL FORMAT on the
- track where bad sector is encountered to mark that sector as a bad. It could
- cause damage on user data, even if scanning itself is non-destructive (also on
- MFM, RLL disks). Therefore, DON'T USE this option to on AT-Bus (IDE), SCSI or
- ESDI drives. These drives store the bad block data themselves, so you don't
- have to tell them or scan the media! Recommendation: use a media analysis
- program provided by an utility package or your hard drive manufacturer.
-
- 10.0 WRITE TO CMOS AND EXIT
- ==================================
- Save the changes you made in the CMOS. You must do that to permanently keep
- your configuration.
-
- 11.0 DO NOT WRITE TO CMOS AND EXIT
- ==================================
- If you are not sure of the changes you made in the CMOS settings, use this
- option to exit safely.
-
- 12.0 FREQUENTLY ASKED QUESTIONS (FAQ)
- ==================================
-
- 1) How do I clear the BIOS memory?
-
- a) Disconnect battery.b) Insert appropiate jumper (see mainboard
- documentation, near battery). Sometimes this is possible with DIP switches on
- the motherboard. Sometimes (if not), you will have to remove the battery. And
- sometimes (if no DIP's and no removable battery, and not willing to desolder
- the battery), you can short the battery with a resistor to lower the current
- available for the CMOS.
-
- This is only recommendable as a very last option. The NiCad cells often
- employed have a very low internal resistance, so that the resistor will have
- to be of very low value for the voltage to drop significantly. The
- corresponding current would be quite high, which is not very good for battery
- life. A better option would be to use a resistor to discharge the battery.
- Obviously, this only makes sense when you have a NiCad cell (which will be
- recharged every time you turn the computer on) as opposed to a lithium cell
- (which cannot be recharged). In the former case, a resistor of 39 Ohm will
- discharge the battery in under half an hour relatively safely.
-
- Another good way to discharge the NiCad is to put a 6 volt lantern lamp across
- it, and let it discharge completely. Not only does it provide an effective
- load, it also gives a visual indication of the charge state. It's a good way
- to prevent "ghost memory" that's so common to NiCads. Metal Nickel Hydride
- batteries are now being seen in some systems. They don't have this problem
- and they are more $$.
-
- 2) Can I upgrade my BIOS?
-
- Most BIOSes are specifically designed for a motherboard and its chipset.
- Therefore, on rare occasions you can upgrade your BIOS for a newer version. It
- is often less troublesome to buy a new motherboard that comes with its own
- BIOS and transfer your CPU (memory, cache memory and adaptor cards...) than
- start hunting around for a new BIOS chip. I know very few computer stores who
- sell BIOS chips separately. However, it is possible to upgrade your BIOS so
- it may support new hardware. By browsing in computer magazines (like Computer
- Shopper, PC Magazine, etc...) you will find adds on companies that specialize
- on that sort of thing. The information they need is the Serial Number for the
- BIOS chip. It is the *long* number that prints out when you boot up. It
- includes the BIOS date, the chipset, etc. (see section 2.0). The price tag
- can vary greatly (from $10 to $80), so are the BIOS upgrades offered. (Does
- anyone have supplementary information on this, like good-bad experiences with
- BIOS upgrade? I already had 2 feedbacks on this, and they all aggree it is a
- little tricky, but it works).
-