>They are made by (apparently) USDC, model number 1101, revisions "01" and
>"BG". The chips are marked circa 1982. They have a Z80, som EPROM, a
>couple of PALs, and a 40 pin IDC header. They are half-height boards (
>i.e. two sets of fingers). "LSI-11 Host Interface" is silk screened onto
>the board under the part number.
>
>Can anyone tell me what these are? They came out of an 11/23 box badged
>11-DM4, althought the box is in the truck and I may have the DM$ slightly
>incorrect.
USDC= U.S. Design Corporation. They're based in Maryland, not too far
from where I now live. They sold (among other things) disk subsystems.
The one you have emulates RK06/RK07 drives, and hooked (via the 40
pin connector) to an external box that had a hard drive (either a 5.25" MFM
or a 8" non-MFM) with electronics that converted the native
drive interface to the 40-pin interface. You might have seen the
appropriate drive boxes in my storage space in Surrey, if you remember
our trip there :-). They're 5.25" rack-width boxes, have black fronts with
a row of bar LED's that blink in a cylon patterm when running, and are about
25" deep - you ought to head back out to UBC and see if there are any
USDC boxes meeting this description there. I still have the drives and
the interfaces, but it's been years since I've powered them up.
The controller is 22-bit-Qbus capable, but the PDP-11 OS's only know of
Unibus RK06's/07's, so machines with more than 256kbytes of memory
generally had USDC patches made to the OS drivers so they knew how to
do DMA to high memory.
--
Tim Shoppa Email: shoppa_at_trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Received on Wed Apr 21 1999 - 16:03:43 BST