6 Jun
2015
6 Jun
'15
2:39 p.m.
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