Rescue update: DEC RC-25s + / was Re: DEC cartridge ID

[joseph lang]

it's true very little LESI documentation escaped...But the klesi schematic
did. and it's well commented. lots of descriptive signal names. The
hardware to interface to it is almost trivial. I took a couple of hours
looking over the schematic and have written a couple of pages describing
how to make it work. Happy to send to anyone who wants it.
Writing  MSCP emulation is beyond my skill level. But i can read a
schematic.

joe

On Thu, Jun 4, 2015 at 11:56 PM, Robert Armstrong <bob at jfcl.com> wrote:

> >Ethan Dicks [ethan.dicks at gmail.com] wrote:
> >did not come with a removable cartridge so I've not been able to spin it
> up
>
>   Yes, one of the annoyances of the RC25 is that you can't spin it up w/o
> the removable platter in place.  I have only one cartridge myself, and it's
> probably bad.  Somebody needs to come up with a hack to spin up the
> Winchester part alone (hint, hint :-)
>
> >One I've seen is to nibble a chunk out of the rim of the cover skin (to
> prevent pinching) and run a BC-11-A
> > Unibus ribbon cable out to a BA-11 and stick any number of controllers
> in that
>
>   Doesn't the 725 have one of the regular bulkhead connector panels on the
> back?  The one with the modular screw in plates?  If so, ISTR that there's
> a cable clamp one that will clear a BC11 cable.
>
>   In any case, I have no need for such foolishness :-)  I have a perfectly
> good 730 too, with a BA11-K expander in the next rack.  It works great, and
> that configuration (with the 730 instead of the 725) was even supported
> although uncommon.  I should go out in the garage and check how the UNIBUS
> cable is routed for you.
>
>   Besides, the cool thing (for me, at least) about the 725 was the
> packaging.  Any replacement drive would have to fit inside the original box
> to suit my taste.
>
>   The best option I've come up with is an SMD UNIBUS controller (I have
> just exactly one!) and a small SMD drive.  There were some small SMD drives
> that I think would fit inside the 725 case.  The front panel wouldn't be
> right, but it's better than nothing.  As you said, SCSI would be better,
> but I don't have a UNIBUS controller.
>
>   What I'd really like is to build a "LESI disk emulator" that could just
> plug into the AZTEC controller, but as far as I've ever been able to
> determine, DEC never documented LESI.  Or at least none of the
> documentation ever escaped.
>
>   BTW, my 725 is missing the outer sheet metal skin.  The previous owner
> apparently didn't think it was important and discarded it.  If anybody
> happens to have an extra VAX-11/725 skin, I'd love to know.
>
> Bob
>
>
>