Debug GC 8005
| Field | Computer Repair |
| Went Obsolete | +10 years ago |
| Made Obsolete By | IDE Hard Disk |
| Knowledge Assumed | MFM Hard disk head/sector/cylinder count and DOS debug |
| When useful | When MFM stepper motor needed realignment |
When a MFM hard disk was hopelessly corrupted, and / or head to track alignment was out of whack due to stepper motor stretching or wearing, causing play, a low level would usually correct this.
In these cases, exact knowledge of the drive geometry was required, which was rarely found on the disk itself.
After invoking debug at the dos prompt, and assuming your computer had a Western Digital MFM controller, you could invoke the low level by typing “g=c800:5” at the debug prompt.
addendum: actually, this command would invoke the burned-into-ROM formatting and other utilities present in the disk controller board and was used (by me, many times) to prepare a new hard disk drive by first entering the (often lengthly) list of defects that was printed on a sheet of paper that would accompany the drive, or were either dot-matrix printed or even handwritten on a permanent label on the drive, then executing the low-level format command. it had little to do with stepper motor realignment.
