RL02K Pack Reliability/Characteristics

Johnny Billquist bqt at update.uu.se
Mon Mar 30 04:26:43 CDT 2015

On 2015-03-30 08:46, Paul Anderson wrote:
> Were all of the packs written on systems with the same word length? If come
> were written on a PDP8-A, You might get garbage reading them on a PDP11.

For some definition of garbage, sure. But it would be the same garbage 
every time.
The RL02 pack will use the same physical format no matter if used on a 
PDP-8 or PDP-11.


> On Mon, Mar 30, 2015 at 12:47 AM, Christopher Parish <
> christopher.parish at parishcomputers.com> wrote:
>> I've gotten my RL-02 -> USB Mass Storage controller mostly working with a
>> few residual gremlins.  Specifically, I've noticed from my testing that I
>> have good packs, ones that read out almost the same every time, and bad
>> packs, ones where half the bits seem to be in different states every time I
>> read them.  I've left write support untested until I can solve this problem.
>> Right now, my working theory is that different controllers had slightly
>> different timing characteristics, and I may need to adjust more of my DPLL
>> parameters dynamically to deal with that (something I'd rather avoid).  Of
>> course, most of these packs haven't been put into a drive since the
>> mid-80s, and there could be some bit rot going on.
>> As many of you have much more experience dealing with these drives than I
>> do, my questions are:
>> - What type of long term reliability have people noticed from their RL02K
>> packs?
>> - Is garbage data sometimes normal for certain packs until they are
>> rewritten with “fresh” data?
>> - Has anyone noticed pack compatibility problems between various
>> computers/RL-02 controllers?
>> Thanks,
>> Christopher

Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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