TROUBLESHOOTING POST PROBLEMS

POST = Power On Self Test

NOTE: When working on a computer, always maintain proper ESD (Electro Static Discharge) prevention procedures.

There are many things which can prevent a POST. An IDE (or EIDE) device (hard disk, CDROM, etc) gone bad, any plug in card either gone bad or loose/dirty, RAM bad/loose/dirty, power supply failing (delivering below tolerance voltages), etc.

If the machine is getting power to the motherboard, but won’t post, remove everything (including the cmos battery) but the CPU, one stick of RAM (ensure it’s in memory slot 1, inserting it two or three times to help clean oxides from the contacts), and the video card if so equipped (seat this two or three times as well). Remove the floppy and IDE data cables connectors from the motherboard end. Remove power to any disconnected devices.

Insert the cmos battery. Try to boot the machine. If it POSTs, power down and add your next RAM stick(s), one at a time with a power-up/boot between every add. Power down for every item addition.

IMPORTANT: Depending on your bios, you may have to enter the bios setup (http://www.d-a-l.com/faq/faq/23.html) and reset the NVRAM and/or “Update Configuration” switches at each boot.

If it doesn’t POST with the bare minimum components, the problem is one of those components. Depending on the age/use of the machine, the logical place to start would be the power supply (and video card). Testers for PS’s can be obtained for little money. After that, if you don’t have the equipment to test motherboards, CPU’s etc, or, a supply of extra compatable components laying around, it’s best to take it to a reputable repair shop for testing.

Next add the floppy data cable (align red/blue stripe/Pin 1 correctly) and power to the drive. Try to boot with a floppy boot disk. If successful, (power down) and add IDE #1, with master disk only connected to the data cable. Connect drive power cable. Boot without a floppy bootdisk this time. Because the bios was reset to factory defaults (battery removal) the disk should be automatically detected. If everything is OK, power down and add the slave device/cabling to IDE #1. Repeat the boot process.

Connect/test IDE #2 next, in the same manner, one device at a time. Get the IDE devices running first then go on to any plug in cards. Continue this way until you encounter the POST fail again. If you do, the last device is the cause. If you don’t, you’ve successfully cleaned/reseated all your connections and the machine should be OK unless there is an intermittent failing device.

Note: Many people will interchange the terms “bios” and “cmos“. For the purposes of this article, the term “bios” will be used.

BIOS = Basic Input Output System

Brief Overview

The BIOS is a program pre-installed on computers (with the exception of Macs) that the computer uses to start up. The CPU accesses the BIOS before the operating system is loaded. The BIOS then checks all your hardware connections and locates all of your devices. If everything is OK, the BIOS loads the operating system into the computer’s memory and finishes the boot-up process.

Since the BIOS manages the hard drives, it can’t reside on one, and since it has to be available before the computer boots up, it can’t live in the RAM. The bios is located in the ROM (Read-Only Memory) of the computer. It resides in an eraseable programmable read-only memory (EPROM) chip on the computers motherboard. So, as soon as you turn your computer on, the CPU accesses the EPROM and gives control to the BIOS. The BIOS is also used after the computer has booted up. It acts as an intermediary between the CPU and the I/O (input/output) devices. Because of the BIOS, your programs and your operating system don’t have to know exact details (like hardware addresses) about the I/O devices attached to your PC. When device details change, only the BIOS needs to be updated. You can make these changes by entering the BIOS when your system starts up. To access the BIOS, hold down the appropriate key as soon as your computer begins to start up.

On the majority of todays computer systems, the bios is entered by pressing a key or a key sequence on power up. Usually on the first screen display you see will be the instructions for the key sequence required to enter the bios/cmos. The BIOS setup program can normally be entered only during the boot process, either on a cold boot, or a warm boot (after hitting {Ctrl-Alt-Del}). Some setup programs (example; early ACER systems) will let you go into the setup program using a key combination once the system has fully booted/started.

The use of the delete key {Del} to enter the setup program during boot is becoming standard. AMI and Award BIOS, and some others as well now use this. Older BIOSes can use any of strange key combinations, including Esc, F1, F2, F10, Ctrl-Esc, Alt-Esc, Ctrl-Alt-Esc, Ctrl-Alt-Enter, Ins or others. If one of the above key sequences does not enter the bios setup program, you will have to seek out a manual for your system, or go the the manufacturers website for instructions. Phoenix (Hewlett Packard) use F1. The POST (Power On Self Test) screen (or “Diagnostic” screen) will be hidden by default on some systems, such as HP, Dell, and Compaq. Instead you will see a screen bearing the logo of the manufacturer. When this screen first appears, this is when you enter the key sequence for the bios setup. This manufacturers “splash” screen can be set to hidden (allowing you to see the boot process) once you enter the bios.

Once you enter the bios setup, you will (usually) end up in the first basic setup screen for your system. This is where the time and date, floppy drive and hard disk parameters are set. There may be another screen or section for hard disk or IDE auto detection. If utilized, this will set the hard disk parameters in this first Basic setup screen.

The boot sequence for system start up will usually be in the ADVANCED (or BOOT with Phoenix bios) section. This is where you can choose the boot device order. For the average user, the sequence is A: (or floppy drive), CDROM drive, then the first IDE hard disk (labeled 0 or 1, depending on how your system is designed). On todays systems, there is also a choice for booting to “other devices”, such as a Network. (When the bios is reset to factory defaults, this boot sequence is usually used.) On some older systems, the CDROM may show up as NONE. This is normal for these systems. The CDROM is usually identified on the POST screen, such as; “Found - LG CRD-8320B” or similar. So even though it’s not listed in the bios, the system knows it’s there.

One last thing to mention, some bios will not recognize changes, new RAM (and other devices) unless you set the “Reset Configuration Data” option (if it exists in your bios) to YES. Once you save your changes, and the system boots successfully with the new changes, this switch will be automatically reset to NO, until you enter the bios once again and change it.

Getting Started

Before formatting your hard disk you may want to make sure you have a few things covered…

• Formatting will completely wipe your computers hard disk so make sure you have backups of all personal files you wish to keep on the PC
• It is likely your PC came with a number of CD’s and manuals so make sure you have all of those to hand. If you have a CD with SYSTEM RESTORE on it this will be better to use so keep hold of this as it will do a lot of the hard work for you.
• Make sure you have copies of software which you may want to reinstall like Microsoft Office.
• It is a good idea to make a note of what graphics card you have and any specific devices you have installed in device manager.

If you have Win98, ME or XP, create a Startup disk. These disks will load CD-ROM drivers at the boot. If you are using Windows 95, you will need to create a bootable disk and add the CD-ROM drivers for your CD-ROM.

Using FDISK

Before you install your operating system, you must first create a primary partition on the hard disk on your computer, and then format a file system on that partition.

1. Insert your Startup disk in the floppy disk drive and boot the computer.

If you are installing Windows 98, 98SE or ME you need to do the following.

a. At the Startup menu is, select Start computer without CD-ROM support and then press ENTER.

b. At the a: prompt type FDISK, and then press ENTER. If you are at the C: prompt simply type a: to switch to the a: prompt (this is your floppy drive) 2. Your hard disk is most likely larger than 512 MB so you will receive the following message:

Your computer has a disk larger than 512 MB. This version of Windows includes improved support for large disks, resulting in more efficient use of disk space on large drives, and allowing disks over 2 GB to be formatted as a single drive. Do you wish to enable large disk support? NOTE: If you want to use the FAT32 file system, press Y and then press ENTER. If you want to use the FAT16 file system, press N, and then press ENTER. For additional information about the FAT32 and FAT16 file systems see below.

http://www.microsoft.com/windowsxp/using/setup/expert/russel_october01.mspx

3. After you press ENTER, the following FDISK Options menu is displayed:

1. Create DOS partition or Logical DOS Drive 2. Set active partition

3. Delete partition or Logical DOS Drive

4. Display partition information

5. Change current fixed disk drive
Note: Option 5 is available only if you have two physical hard disks in the computer. 4. Press 1 to select the Create DOS partition or Logical DOS Drive menu option, and then press ENTER.

5. Press 1 to select the Create Primary DOS Partition menu option, and then press ENTER.

6. After you press ENTER, you will receive the following message:

Do you wish to use the maximum available size for primary DOS partition?

Note: After you receive this message, use one of the following methods, depending on the file system that you selected.

For a FAT32 File System

If you pressed Y for the FAT32 file system (in step 2) and you want all of the space on the hard disk to be assigned to the c: drive press Y and then press ENTER.

a. Press ESC, and then press ESC to quit the FDISK tool and return to a command prompt. For a FAT16 File System

If you press N for the FAT16 file system (in step 2), you can accept the default 2 GB size for the partition size, or you can customize the size of the partition.

To accept the default partition size: a. If you want the first 2 GB on the hard disk to be assigned to drive C, press Y, and then press ENTER.

b. Press ESC to return to the Options menu, and then continue on with the following “To customize the partition size” section.

To customize the partition size:

a. If you want to customize the size of the partitions (drive letters) on the hard disk, press N, and then press ENTER.

b. A dialog box is displayed in which you can type the size that you want for the primary partition in MB or percent of disk space.

Note: For computers that are running either Windows 98 or Windows Me, Microsoft recommends that you make the primary partition at least 500 MB in size.

c. Type the size of the partition that you want to create, and then press ENTER. d. Press ESC to return to the Options menu.

e. To assign drive letters to the additional space on the hard disk, press 1, and then press ENTER.

f. Press 2 to select the Create Extended DOS Partition menu option, and then press ENTER.

g. You will receive a dialog box that displays the maximum space that is available for the extended partition. You can adjust the size of the partition or use the default size. Note that the default maximum space is recommended, but you can divide the space between multiple drive letters. Type the amount of space that you want, press ENTER, and then press ESC.

h. The Create Logical DOS Drive(s) in the Extended DOS Partition menu is displayed. This is the menu that you can use to assign the remaining hard disk space to the additional drive letters. Type the amount of space that you want to assign to the next drive letter in the Enter logical drive size in Mbytes or percent of disk space (%) box, and then press ENTER.

i. A table that lists the drive letter that you created and the amount of space on that drive is displayed. If there is free space on the hard disk, it is displayed near the bottom of the table. Repeat steps a through i until you receive the following message:

All available space in the Extended DOS Partition is assigned to local drives.

j. After you receive this message, press ESC to return to the Options menu.

k. To activate the partition from which you plan to boot (usually drive C), press 2 to select the Set active partition menu option, and then press ENTER.

l. When you receive the following message, press 1, and then press ENTER:

Enter the number of the partition you want to make active.

m. Press ESC, and then press ESC to quit the FDISK tool and return to a command prompt, now reboot your PC keeping your startup disk in the floppy drive.

In the previous section “Part 2: How to Use the FDISK Tool” the FDISK command was explained how to prepare the drive to be formatted. In this article the focus is on the format command.

Before beginning to format the hard drive check to make sure all the required software and disks are available. Review the “Getting Started” section on “Part 1: Formatting Your Hard Drive”.

Formatting the Hard Disk

BE AWARE THAT THIS COMMAND WILL COMPLETELY WIPE THE DATA FROM YOUR HARD DISK SO ONLY USE THIS COMMAND IF YOU ARE SURE YOU WISH TO ERASE ALL DATA FROM THE HARD DISK.

1. You should have just rebooted the machine after using FDISK so now your PC will be booting once again from the floppy drive. If you are installing Windows 98, Windows 98 Second Edition, or Windows ME:

a. When the Microsoft Windows 98 Startup menu is displayed, select the Start computer without CD-ROM support menu option, and then press ENTER.

b. At a command prompt, type in without quotes, “format c:” and then press ENTER.

NOTE: If you receive a “Bad command or file name” message, you may need to extract the Format.com utility to your Startup disk. To do this, type the following command at a command prompt, and then press ENTER:

extract ebd.cab format.com

After the Format.com utility is extracted to your Startup disk and a command prompt is displayed, type format c:.
c. When you successfully run the Format.com utility, you receive the following prompt:

WARNING, ALL DATA ON NON-REMOVABLE DISK DRIVE C: WILL BE LOST!

Proceed with Format (Y/N)?

Press Y, and then press ENTER to format drive C.

d. After the format procedure is finished, you receive the following prompt:

Volume label (11 characters, ENTER for none)?

This is an optional feature that you can use to type a name for the hard disk. Type an 11-character name for the drive, or leave it blank, and then press ENTER.
e. Repeat steps a through d for any additional drive letters that you created.

INSTALLING THE OPERATING SYSTEM

Now you hard disk is ready to load the operating system.

You may have a bootable CD so try putting this in the CD drive first and reboot the machine. You may have to go into the BIOS and make the CD-ROM drive the first bootable device. If you PC does not recognise the CD the PC will not boot and you will have to boot from your floppy boot disk again.

Reboot with your floppy startup disk.

a. When the Microsoft Windows 98 Startup menu is displayed, select the Start computer with CD-ROM support menu option, and then press ENTER.

Once at the E: or D: drive depending on the drive letter for your CD-ROM drive you need to run the setup.exe on the CD. The setup.exe could be located in a few different folders on the CD so browse the CD using dir command and switch folders using the cd command until you find setup.