23 Jul
2003
23 Jul
'03
5:39 p.m.
Jerome H. Fine wrote:
Oh no, there is a unibus DSD controller, I'm absolutley positive about
this. I've owned two, and serviced
a great many back in the Eli Heffron days.
Bob Shannon
wrote:
The DSD boxes I used do not emulate DEC drives,
and made the 45 meg hard
drive
available as a single device.
Jerome Fine replies:
As far as I know, the DSD 880/8 and the DSD 880/30 all used
only a Qbus controller. And they accepted the standard DEC
device drivers in RT-11.
There may have been other DSD boxes in addition the the DSD 880
and DSD 440, but I had not heard about them, let alone the details.
All my DSD experiance is unibus based. Qbus machines have no
blinkenlights, and are in my eyes,
unworthy.
I have, err, well, Jay West has a DSD floppy-only
(RX-02) emulation in
his 11/34a out
in my garage, and that does use the standard driver.
That was the DSD 440 which emulated the RX02. For this drive,
I used BOTH a Unibus controller on a PDP-11/34 and a Qbus
controller on an LSI-11 within a VT103. What I found MOST
amazing at the time (1979) was that the same RX02 floppy would
BOOT on BOTH the Unibus and the Qbus systems even though
the hardware was so different - especially the CPUs. RT-11
was able to self-configure on the fly to whichever hardware was
present during the boot phase.
I guess DSD had many varients, and we must be
talking about different
products.
Seems like it. BUT the header stated DSD 880, so I went along
with it. Any idea what the actual hardware was?
But the unibus version of the DSD interface for
the floppy-hard drive
combo's I've
worked with all needed a DSD driver for RT-11.
Again, was that a DSD 880/8? If so, DSD did provide a driver
for the RL02 interface which normally used 10 MBytes to allow
for the 8 MByte hard drive. I don't feel that this was a special
DSD driver that was essential since the standard DL(X).SYS
could be used with the DSD 880/8 to give a 5 MByte usage
of the hard drive as an RL01 drive. That meant that 3 MBytes
were lost to the user, but it would still work with the standard
distributed DEC RT-11 device driver.
Sincerely yours,
Jerome Fine