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Thread: PDP-11 under Simh. Trying to create empty disk image.

  1. #1
    Join Date
    Mar 2007
    Location
    Leicester, UK
    Posts
    189

    Default PDP-11 under Simh. Trying to create empty disk image.

    Hi Folks,

    I have RT-11 on a simulated PDP-11 under Simh.
    I would like to create another disk image (perhaps an RD54) that is empty and full sized on the native OS (Linux) so that I can copy it to an SD card to pop into an SCSI2SD interface.

    I can't for the life of me see how to create an empty, full sized image (i.e. one that already occupies its full size on the native system rather.

    Please can someone help?


    Thanks,

    Andy.

  2. #2

    Default

    I don't know what kind of pdp-11 you have. But what I did was use the Linux dd command to create a new file from the simh file.

    Here is a link to someone doing the same thing. I also don't know what you're using as your SCSI interface on the 11. I have a UC17.

    http://www.vcfed.org/forum/showthrea...-card-PDP11-83

  3. #3
    Join Date
    Nov 2014
    Location
    Chicagoland
    Posts
    161

    Default

    If you add an "attach rl3 empty.fil" in the SIMH .ini file, SIMH will report "RL3: creating new file" and zero fill it the next time it starts. If you try a "DIR DL3:" it will report ?DIR-F-Invalid directory, but that's not a surprise since its an completely un-initialized disk. Just go ahead and "INIT DL3:" and proceed.

    For MSCP (RDnn) drives, you have to fiddle a bit with the "SET DU" command to get unit N to match the device RQn - see http://avitech.com.au/?page_id=934. MSCP drives can be a variety of sizes, see the "SET RQn Rxxx" for types of drives to emulate. Also check out the "SET {dev}n AUTOSIZE" command to use on images whose sizes are not standard.

    Jerry

  4. #4
    Join Date
    Mar 2007
    Location
    Leicester, UK
    Posts
    189

    Default

    Thank you both very much.

    That's the information I needed.

    I am using an MSCP controller and as I said running RT-11 and so the avitech article is very useful as it explains the 32MB limit which I wasn't aware of.

    I found this interesting table of disk geometry http://www.ultimate.com/phil/pdp10/dec.disks, which, in connection with tradde's suggestion would mean you could create any of DEC's disks if for any reason simh couldn't so it or you didn't want to use simh but go straight to an image to drop on an SD card and onto real hardware.

    Thanks again Folks, I'm off to experiment.


    Cheers,

    Andy.

  5. #5
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,152

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    Hi Andy,

    Got bored of Pacman and Space Invaders now?! Onto something else...

    Dave

  6. #6
    Join Date
    Mar 2007
    Location
    Leicester, UK
    Posts
    189

    Default

    Hehehe How could I?

    I was given an SD card image with those bits on but I need to be able make other partitions to properly "Set up my stall" and reclaim the unused space on my SD card.

    I'm well on the the way now.


    Andy.

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