20 Dec
2013
20 Dec
'13
11:51 a.m.
On Fri, Dec 20, 2013 at 03:58:48PM +0100, Pontus Pihlgren wrote:
There are pci to unibus bridges. I think they sre made
for
use with some emulator. Perhaps it was qbus.. i'm not sure
now.
Both exist, but unfortunately they're quite expensive ($3500 a pop).
I've got some other USB projects in the works and have given quite a bit
of thought to Unibus -- a general-purpose, emulator-compatible NPR-capable
interface would be impossible because of the slow 1-msec response time
(NPR masters time out if the PDP-11 memory doesn't respond within ~10 usec),
but some sort of oddball doodad that has its own on-board memory and isn't
compatible with anything (and so would need its own drivers for every possible
disk/tape) could be done.
An EPP parallel port might work a lot better as the host (they're still
available as PCIe cards which may be better anyway since ISA-like timing
would be too slow), although the interrupt response still might not be
fast enough to handle NPRs.
A direct USB-to-RL01/02 interface is on my to-do list but there's a bunch
of stuff higher up on the list. Eventually I'd like to build USB interfaces
for all the basic DEC disks, to make them look like USB flash disks, so that
they'll work with any OS or emulator or utility or just the Weenix "dd"
command. That way you can easily deal with foreign disks whether or not you
like the software "nest" that's been built for that interface (I'm
looking at
you, Catweasel!). Bunch of other stuff to finish debugging first though.
John Wilson
D Bit