[vcf-midatlantic] LSI-11 simulator (looking for the author)

Richard Cini rich.cini at gmail.com
Thu Sep 10 13:50:23 EDT 2020

I re-read the article again and he does make that statement, yes. But, when discussing it a few weeks ago, he didn’t seem to think he did that. So, that’s what let me to finding out a way to modify the simulator to work with an existing disk image rather than writing a custom PF driver and putting it on a disk image – mostly because I have experience in writing emulators and almost zero experience in writing/modifying native PDP code.


The RXV11 manual only has some basic code samples, not the device driver code. I recall seeing it somewhere, but of course, I don’t remember which manual it might have been in…





Rich Cini





On 9/10/20, 1:40 PM, "Kenneth Gober" <kgober at gmail.com> wrote:


On Thu, Sep 10, 2020 at 10:10 AM Richard Cini via vcf-midatlantic <vcf-midatlantic at lists.vcfed.org> wrote:

I was able to locate and correspond with the original author, and he doesn’t recall creating custom disks or disk images. Hmmm.


The original author might not have created a custom disk or disk image, he might instead have created a custom PF device driver, then made a bootable "PF" disk the normal way using PIP or whatever.  I have a vague idea that RT-11 does this by copying a part of the PF device driver to the boot block, then arranging for the rest of the device driver to reside at a particular place on the disk (where the boot block code expects to find it).  The magazine article referred to the need for a custom PF driver, did it not?


Technically the result could be considered a "custom" disk but when you're dealing with decades-old memories the distinction between "custom" and "standard" might apply more to the procedure used rather than the end result.  In other words, I might recall editing a disk image with a hex editor as making a "custom" disk, but if I had produced exactly the same result using standard OS tools I might not.remember this as being "custom" at all.



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