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If there is a duplicate copy of
master boot sector found before location of volume boot sector, then it is possible that a boot virus has infected hard drive in system. The Rebuild Master Boot feature of Micro-Scope will eliminate any boot sector virus. Be sure to boot system to Micro-Scope diskette and immediately do a cold reboot of system after using Rebuild Master Boot feature.
If volume boot sector is found in a location other than cylinder 0, head 1, sector 1, count actual number of sectors before volume boot sector, and compare that value to value for sectors per track displayed in partition table described in step 2. If values match, most likely cause of system failure is an incorrect CMOS setup. In this case CMOS needs to be reset to values indicated by partition table described in step 2, remembering to use formula described in step 2 when doing so. If values do not match, set CMOS Sectors Per track to number of sectors counted before volume boot sector and continue to next step.
Step Five: Check partition tables to make sure they are correct
Reboot system to Micro-Scope and go to System Configuration, Partition Tables. Check information displayed in master boot record to see if there is any obvious corruption (that is, excessively large numbers, all partitions non-bootable, etc.) If there is no obvious corruption in master boot record, then perform step 2 again. If information matches at this point, go to step 6. If information does not match, then set sectors per track in Master Boot Record to number of sectors per track currently set in CMOS, set starting head to 1, starting sector to 1, and starting cylinder to 0, and write information to drive.
Step Six: Verify Master Boot Sector information
Display Volume Boot Sector and use values for heads and sectors per track (on right half of screen) to perform step 2 again.
If values match, then volume boot sector is probably okay. If any values in Master Boot Record do not match table to right, reset values to match values in table, and write to drive.
If values still do not match, both Master Boot Record and Volume Boot Record are probably corrupt. At this point, e-mail Technical Support for help in this situation. Future articles will provide more insight into repair procedure.
Step Seven: Check FATs
Check to see if first FAT starts on sector just beyond volume boot sector. Use find feature in Fixed Disk Editor to search for F8 FF FF in first three bytes of each sector. The first occurrence should be on sector two of head one. Continue to search until second FAT is found, indicated by second occurrence of F8 FF FF. Note location of cylinder, head and sector of second FAT.
Based on start of second FAT, and start of first FAT, calculate how many sectors are in first FAT. If necessary, read each sector starting at first sector of first FAT, keeping a count of sectors that have been read until F8 FF FF is seen in upper left of HEX display, which would indicate start of second FAT. After calculating sectors per FAT, compare this value to value in volume boot sector. If values match, drive should be accessible through DOS at this point.
Step Eight: Attempt to access drive
Boot to a DOS-bootable floppy diskette and attempt to access drive. If root directory and sub-directories on hard drive are readable at this point, then attempt to boot to drive. If drive boots at this point, problem has been corrected. If drive is still not bootable, e-mail Micro 2000 Technical Support department for help.
Disclaimer - The Micro 2000 Tech Tip is a free service providing information only. While we use reasonable care to see that this information is correct, we do not guarantee it for accuracy, completeness or fitness for a particular purpose. Micro 2000, Inc. shall not be liable for damages of any kind in connection with use or misuse of this information.
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