RL02K Pack Reliability/Characteristics

[Paul Koning]

> On Mar 30, 2015, at 7:50 PM, Christopher Parish <christopher.parish at parishcomputers.com> wrote:
> 
> ...
> Second, I've noticed that the drive seems to mis-seek on occasion.  I command the drive to walk forward or back a single track, and the heads move but sometimes land on the same starting track.  This results in duplicate data for the next 10kB or so, and is heavily pack dependent.  Some packs don't exhibit it, others do.  I imagine this is related to the drive/pack runout condition described in the manual.  Until I figure out more, my plan is to add additional verification to the incoming data, checking the track it landed on and re-commanding the difference if necessary.

As I recall, RL01/02 have embedded servo (one of the first DEC drives to do so).  That would suggest you have a marginal servo mechanism.  As for wrong data, isn’t there a track (cylinder) number in the headers?  I would expect there to be one, so a wrong seek should be detectable.

	paul