Data Systems Design DSD-880 8" floppy and hard drive?

From: Jerome H. Fine <jhfinexgs2_at_compsys.to>
Date: Tue Jul 22 21:30:00 2003

>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.

> 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
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Received on Tue Jul 22 2003 - 21:30:00 BST

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