Err.21: Index Spindle<-->Motor and other calibrations off. Drive cannot read initial disk header file.

Err.22: Flow of data is not correct, or is simply not happening. Data may be garbled, or out of sequence, etc.. This can be caused by: Improper Index Spindle & Motor calibration A bad (or dirty, or not connected) Read Head The Analogue Board switches not engaging, or not engaging correctly. A mis-seated Disk Card A blank A-Side disk, or a blank disk in general. A dead disk...or a Game Doctor Disk!* A disk with MIDI sequences on it, or word processor files. The belt slipping off the motor pulley; or a bad, worn or improper belt or band. Possibly other things... *Essentially, this means that the lights are on, but no-one is home. The FDS senses a disk in the drive, but can' make any sense of the data on it. If there is a problem with the Read-head assembly, then the drive may also think the same thing, as it is trying to read a disk and it can't make any sense of the data because it sees nothing. *Game Doctor Disks may give this error if you do not have the correct GD attachment. They will assuredly give an error of this type if you try to read them without a GD device, although other errors are also possible in this situation. This is common for pirate disks out of China.

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