Well, yesterday they posted a second video on matters involving formatting disks. (16½ minutes) This time they went over a routine written, for the same drives, that can format a disk in 15 seconds.

So, how can this new formatting method be more than four times faster? In a few ways. The drive’s normal format routine writes 1 bits throughout each entire track; the 15 second formatter doesn’t do anything like that. The stock routine attempts to size the between-sector zones differently depending on how far from the center the track is, and to make that work better it performs a measurement of how fast the drive motor runs. The quick format just uses a same-sized gap throughout the disk. It still reads okay because the drive uses the sync marks to find sectors, it doesn’t try to time the length of gaps when reading, it just looks for a sequence of 10 1 bits in a row. And Commodore’s format routine verifies each track as it’s recorded to the drive; the 15 second format simply moves on, assuming everything worked out.

The result is, the quick formatter does a worse job of setting up the disk, skipping some of the niceties of Commodore’s routine. I wonder if there are some cases where the quick format produces a non-working disk? The video notes that, because there could have been data on the disk before, it could result in cases where the drive gets confused when that leftover data resembles a sync mark or other essential drive structure. Commodore History mentioned at the end of the video that they tried to create such a disk, to see if it caused issues, but was unable to make it happen.

rodneylives