RL02K Pack Reliability/Characteristics

[Paul Koning]

> On Mar 31, 2015, at 11:41 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
> 
> On Tue, Mar 31, 2015 at 11:26 PM, Christopher Parish
> <christopher.parish at parishcomputers.com> wrote:
>> Thanks for your help everyone.  I finally figured out what was happening.  Something is wrong with my (everyone's?) drives.
>> ...this could be totally normal, and the controllers/software drivers hide it.
> 
> I'd have to dig out driver code (perhaps rl.c from 2BSD would be the
> quickest to read and digest if you already know C) but IIRC, yes...
> all the drivers "hide this" because that's what the drives do.  I
> don't know chapter and verse about how they handle multiple 1-track
> seek fails (the OS/8 RL8A driver probably has the least room for fancy
> footwork), but they should all handle this to one degree or another.

The general rule of device drivers is to assume that the hardware is misbehaving, and double check everything.  If it looks like the seek didn’t work right, reissue it, or tell the drive to recalibrate and then reissue it, or whatever it takes to beat the device into conformance.  In the case of the RL01/02, the details are a bit different because seek is by delta rather than absolute cylinder number, but the basic principle carries over.

	paul