RL02 Spinup fails

Jerry Weiss jsw at ieee.org
Sat Nov 11 13:05:24 CST 2017

> On Nov 11, 2017, at 10:58 AM, Aaron Jackson via cctalk <cctalk at classiccmp.org> wrote:
> ……...
> The RL02 technical manual says to figure out why a drive error occurred,
> I can execute a get status command (?) and then perform an MPR read
> (?). So while I don't know how to do that, the error could be one of the
> following (apparently)
> - spin error. I assume it's not this because the ready light is on?
> - seek time out. Maybe this?
> - write lock. Only set when the drive is write protected.
> - current head error. Set when write current is detected while reading.
> - write data error. Set when no transitions are detected during writing.
> So, pretty confused.
> Thanks,
> Aaron.
> ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
>>> Well, some progress.
>>> It seems that a terminator is not required so long as the cable is VERY
>>> short. The controller RLV12 controller appears to have a few termination
>>> resistors on it anyway. There is no fault light appearing and the drives
>>> spin up fine. Mine cable is less than 20cm and the PDP is sitting just
>>> on top of the drive.
>>> I can see that the drive is communicating because the lsb of the csr
>>> changes flips between 0 and 1 when I load and unload the drive.
>>> I wanted to try and dump the disks using vtserver, but when I run the
>>> copy program I end up with the following
>>> ]] Enter name of input record/device: rl(0,0,0)
>>> ]]
>>> ]] Can't get rl(0,0,0) sts
>>> ]] rl(0,0,0) err cy=0, hd=0, sc=2, rlcs=142205, rlmp=0
>>> ]] rl(0,0,0) error reading labelsector
>>> ]] Enter name of input record/device:
>>> The same happened on both packs - they have both been cleaned and look
>>> as though they are in good condition. The heads have been cleaned too.
>>> Given that the drive appears to be communicating with the PDP-11, where
>>> might this problem come from?
>>> Thanks,
>>> Aaron.


Do not underestimate the need for termination, even with a very short external cable.
When you factor in the internal cables runs,  crosstalk or signal reflections which interfere 
with operation may still be present, especially when data transfers start.    

If you have access to another bootable drive (8inch floppy?), suggest you load the
XXDP+ diagnostics for RL Drives.  


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