HDR Drive verification

[Jondav1120]

Hello All,

I have been investigating the Mackie Drive performance verification routine recently using a hex editor to work out what changes are made to the disk when the verification is run. This change is what the OS looks for when determining if the external drive is backup only, or can be used as a recording drive.
The OS looks at bytes 0x09-0x0A within the MBR (first sector on the disk) to determine whether the drive has passed. Passing the verification routine changes the bytes from 0x4F 53 to 0x52 54. Manually changing these bytes on a disk that had been formatted in the recorder but NOT verified, resulted in the disk being recognised as suitable for recording. I have yet to try this on a disk that has actually failed the verification.

These are the two bytes to change...

Bytes to change

2021-06-13.png (Array KiB) Viewed 1283 times

Bytes changed and ready to save back to disk...

Bytes changed...ready to save back to disk

2021-06-13 (1).png (Array KiB) Viewed 1283 times

I will look out a disk that has failed verification in the past and test further, it will be interesting to see if the verification routine really is rejecting disks that are too slow...will try it on a CF card that I know fails the verification as well.

Regards

John

[Jondav1120]

Further experiments show that the performance verification routine is about right. I changed the bytes on a disc that failed and has been used for backup ever since...It then recorded for about 15minutes. Usually it would come up with a performance error, but occasionally it would just hang.
Just for fun, I also tried using a cf card that was known to be too slow as the boot drive, as the HDR seems to assume that the internal drive will always be fast enough. Although it would quite happily boot from this card and record several hours of 44.1kHz/16bit/24tracks, trying it with 48kHz/24bit/24tracks would result in a hang just about every time.

Regards

John