| It is extremely important not to make or | | | | for MSDOS (in DOS based systems) or MSWIN (in |
| write any changes to data on the hard drive | | | | Windows95 systems).If there is a duplicate |
| without first verifying the hard drive | | | | copy of the master boot sector found before |
| configuration. Therefore, the first priority | | | | the location of the volume boot sector, then |
| when unable to access information on a hard | | | | it is possible that a boot virus has infected |
| drive is to verify all of the configuration | | | | the hard drive in the system. The Rebuild |
| information dealing with the suspect hard | | | | Master Boot feature of Micro-Scope will |
| drive.Partition Parameter | | | | eliminate any boot sector virus. Be sure to |
| | | | boot the system to the Micro-Scope diskette |
| Value or EquationPartition Status | | | | and immediately do a cold reboot of the |
| | | | system after using the Rebuild Master Boot |
| BootableStarting Head | | | | feature.If the volume boot sector is found in |
| | | | a location other than cylinder 0, head 1, |
| 1Starting Sector | | | | sector 1, count the actual number of sectors |
| | | | before the volume boot sector, and compare |
| 1Starting Cylinder | | | | that value to the value for the sectors per |
| | | | track displayed in the partition table |
| 0Partition Type | | | | described in step 2. If the values match, the |
| | | | most likely cause of the system failure is an |
| Bigdos (drives greater than 30 MB), | | | | incorrect CMOS setup. In this case the CMOS |
| otherwise DOS 12Ending Head | | | | needs to be reset to the values indicated by |
| | | | the partition table described in step 2, |
| Total Number of Heads -1Ending Sector | | | | remembering to use the formula described in |
| | | | step 2 when doing so. If the values do not |
| Sectors per Track displayed in Volume Boot | | | | match, set the CMOS Sectors Per track to the |
| SectorEnding Cylinder | | | | number of sectors counted before the volume |
| | | | boot sector and continue to the next |
| Number of Cylinders set in CMOS - 2Total # | | | | step.Step Five: Check the partition tables to |
| of Sectors | | | | make sure they are correctReboot the system |
| | | | to Micro-Scope and go to System |
| Number of Sectors displayed in Volume Boot | | | | Configuration, Partition Tables. Check the |
| SectorStart Absolute Sector | | | | information displayed in the master boot |
| | | | record to see if there is any obvious |
| Number of Sectors per Track in Volume Boot | | | | corruption (that is, excessively large |
| SectorBoot Signature | | | | numbers, all partitions non-bootable, etc.) |
| | | | If there is no obvious corruption in the |
| 55AAStep One: Make sure that Micro-Scope | | | | master boot record, then perform step 2 |
| detects the hard driveIn Micro-Scope, System | | | | again. If the information matches at this |
| Configuration, Compare Settings - check to | | | | point, go to step 6. If the information does |
| make sure that there is not an asterisk | | | | not match, then set the sectors per track in |
| beside the number of hard drives detected | | | | the Master Boot Record to the number of |
| value. If there is an asterisk, either the | | | | sectors per track currently set in CMOS, set |
| CMOS is set incorrectly, or there is an | | | | the starting head to 1, starting sector to 1, |
| electronic problem (controller, cable, | | | | and starting cylinder to 0, and write the |
| drive).Step Two: Compare the BIOS parameters | | | | information to the drive.Step Six: Verify the |
| against the drive partition information.In | | | | Master Boot Sector informationDisplay the |
| Micro-Scope, System Configuration, System | | | | Volume Boot Sector and use the values for |
| Information - note the information displayed | | | | heads and sectors per track (on the right |
| for the hard drive, specifically the | | | | half of the screen) to perform step 2 |
| parameters for the drive in question. Compare | | | | again.If the values match, then the volume |
| these parameters to the parameters in the MBR | | | | boot sector is probably okay. If any values |
| display under Micro-Scope, System | | | | in the Master Boot Record do not match the |
| Configuration, Partition Display using the | | | | table to the right, reset the values to match |
| following formula:System Information | | | | the values in the table, and write to the |
| | | | drive.If the values still do not match, both |
| Master Boot RecordCylinders | | | | the Master Boot Record and the Volume Boot |
| | | | Record are probably corrupt. At this point, |
| Ending Cylinder + 2Heads | | | | e-mail Technical Support for help in this |
| | | | situation. Future articles will provide more |
| Ending Head + 1Sectors | | | | insight into the repair procedure.Step Seven: |
| | | | Check the FATsCheck to see if the first FAT |
| Sectors Per TrackIf the information does not | | | | starts on the sector just beyond the volume |
| match, either the partition information is | | | | boot sector. Use the find feature in the |
| corrupt, or the CMOS setup or controller BIOS | | | | Fixed Disk Editor to search for F8 FF FF in |
| setup (if one exists) is incorrect, or there | | | | the first three bytes of each sector. The |
| is a problem communicating with the | | | | first occurrence should be on sector two of |
| drive.Step Three: Check the drive | | | | head one. Continue to search until the second |
| functionalityIn Micro-Scope, Diagnostics, | | | | FAT is found, indicated by the second |
| Fixed Disk Tests - check the information in | | | | occurrence of F8 FF FF. Note the location of |
| the Fixed Disk Selected window. Make sure | | | | the cylinder, head and sector of the second |
| that the proper drive type, model, and native | | | | FAT.Based on the start of the second FAT, and |
| parameters are showing in this window. If any | | | | the start of the first FAT, calculate how |
| of the information is incorrect, there is an | | | | many sectors are in the first FAT. If |
| electronic problem. Check the cable, | | | | necessary, read each sector starting at the |
| controller and drive, re-seating all | | | | first sector of the first FAT, keeping a |
| connections, and repeat the above procedure. | | | | count of the sectors that have been read |
| After correcting the electronic problem, | | | | until F8 FF FF is seen in the upper left of |
| perform a read test on the first 10 cylinders | | | | the HEX display, which would indicate the |
| of the drive. If any errors occur, then this | | | | start of the second FAT. After calculating |
| is the most likely cause of the drive | | | | the sectors per FAT, compare this value to |
| failure. Perform a read of the entire drive | | | | the value in the volume boot sector. If the |
| to determine if the errors are electronic in | | | | values match, the drive should be accessible |
| nature, or physical in nature. Electronic | | | | through DOS at this point.Step Eight: Attempt |
| problems will result in the errors displayed | | | | to access the driveBoot to a DOS-bootable |
| not always being the same type or in the same | | | | floppy diskette and attempt to access the |
| location on the drive. If the problem is | | | | drive. If the root directory and |
| electronic, replace the cable, controller, | | | | sub-directories on the hard drive are |
| and finally drive electronics and repeat the | | | | readable at this point, then attempt to boot |
| read test until no errors occur. If the error | | | | to the drive. If the drive boots at this |
| is physical, use an INT 13 type editor (such | | | | point, the problem has been corrected. If |
| as Norton Advanced Editor), to block the | | | | the drive is still not bootable, e-mail the |
| entire drive and write the information to a | | | | Micro 2000 Technical Support department for |
| daisy chained drive set to the same | | | | help.Disclaimer - The Micro 2000 Tech Tip is |
| parameters as the faulty drive.The next step, | | | | a free service providing information only. |
| after the drive passes the read test on the | | | | While we use reasonable care to see that this |
| first 10 cylinders, is to check the original | | | | information is correct, we do not guarantee |
| partition setup of the drive.Step Four: Check | | | | it for accuracy, completeness or fitness for |
| for the physical location of the master boot | | | | a particular purpose. Micro 2000, Inc. shall |
| sector and the volume boot sector.In | | | | not be liable for damages of any kind in |
| Micro-Scope, Utilities, Fixed Disk Editor - | | | | connection with the use or misuse of this |
| use the FIND feature to search the last two | | | | information.Micro 2000 Inc has been helping |
| bytes of each cylinder for a boot signature | | | | to solve the day-to-day challenges that IT |
| (55 AA). The first location where a boot | | | | departments face in order to keep their |
| signature should be found would be at | | | | businesses operational as well as profitable |
| cylinder 0, head 0, sector 1 (the master boot | | | | for over 14 years. The company's primary goal |
| sector). The second location where a boot | | | | is to put the customer first - through |
| signature should be found is at cylinder 0, | | | | feature-rich, simple-to-use IT tools that can |
| head 1, sector 1 (the volume boot sector). It | | | | help IT administrators manage their jobs more |
| is also possible to use the FIND feature to | | | | effectively. |
| locate the volume boot sector by searching | | | | |