Reading RX01/02 disks on a PC

From: Jerome H. Fine <>
Date: Sun Jan 30 15:48:27 2005

>Vintage Computer Festival wrote:

>So I'm in the process of pulling a bunch of files off of some RX02 disks
>to get them onto a PC.
>So far (thanks to help from Howard Harte) I've got an 11/44 with an RX02
>drive running RSTS that has the DD module loaded. I'm running the serial
>tape drive simulator on a PC (I forget what it's called or who wrote it).
>So I can do:
>COPY DY1:*.* DD0:
>Which then copies all the files off of the disk into an image file on my
>PC. Works very nicely, albeit slowly (only 9600bps transfer rate).
>Is there a better way to do this? I've seen various postings of people
>getting RX02 drives connected to Linux boxen. How so? Has anyone done
>I also found this:
>This is very cool. It's an RX02 simluator (hardware/software) that makes
>your PDP11 think your PC is an RX02 drive. It would be great if I could
>read the files from a real RX02 and then dump them into the emulated RX02.
Jerome Fine replies:

I am fortunate enough to have a SCSI host adapter connected to
a Sony SMO S-501 on the real DEC PDP-11. On the PC,
I have an Adaptec AHA-2940AU host adapter with a separate
Sony SMO S-501. Thus, any files on either system can be copied
to the SMO media and then read on the other system.

Once the media is on the PC, then the PUTR program from
John Wilson is easily able to read the file on the SMO media
and transfer the file to the directory on the PC, although I admit
that I have used PUTR only under Windows 95 and 98 SE.

Of course, I doubt this really answers your question since it
seems like you really want to easily be able to read RX02 media
directly on the PC.

>Can a PDP11 have two sets of RX02 drives installed at once? If so, do the
>second set of drives become DY2: and DY3:?
Under RT-11, it is trivial to perform a SYSGEN
which allows DY2: and DY3:, although you also
must realize that the RX02 controller ONLY supports
18 bit addresses. Of course, the RT-11 operating
system can support the full 4 MByte address space
if there is extra code to support a bounce buffer
within the DYX.SYS device driver.

In addition, it is possible for both a real PDP-11
and an emulator to easily support up to 4 RX02
controllers for a total of 8 DY drives (DY0: => DY7:).
But I don't think that I have ever seen a real PDP-11
system with more than 2 dual RX02 drives. AND as far
as I know, neither emulator for the PDP-11 allows
more than 2 RX02 controllers. BUT, if it was
really important, I am sure that could easily
be changed.

There were also a few third party controllers
that supported hardware 22-bit addresses, but DEC
never bothered to allow this hardware. DECUS
has RT-11 device drivers for RT-11 to support
many of the third party RX02 controllers for
RT-11 which have 22-bit hardware. In addition,
I know where it is possible to find a version
of DYX.SYS which supports a bounce buffer so
that 22 bit user buffers are allowed under RT-11
with only 18 bit hardware for the RX02 controller,
both real DEC RX02 and emulated.

Sincerely yours,

Jerome Fine
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Received on Sun Jan 30 2005 - 15:48:27 GMT

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