I'm not entirely clear about what you mean by "porting".
Are you talking about getting the files and file system across from one
type of device to another? If so, it might depend on the file system in
question, but for the ones I can think of, in general, you can just copy
the content to a larger device and it works just fine. You will not get
access to the extra space though, as the existing file system only knows
about the blocks that existed when it was created.
If you are talking about a bootable system, it's a slightly different
story. The file system parts should still be fine, as mentioned above.
In addition you have the boot block, which contains the boot loader.
This is different for different controllers. In addition, there might be
differences based on disk type, but I think that would be rare.
Moving from an RL01 to an RL02 might work, as it is the same type of
controller. Moving from an RK05 to an RL disk on the other hand most
likely will not result in a bootable system.
Merging several disk images is a very different story, and not something
I would recommend you try. It does not work the way you seem to think.
File systems have very defined ideas about disk content layout.
Appending two file systems does not mean that they suddenly know about
the new bits appended.
Johnny
On 2017-02-05 13:47, B Degnan wrote:
Hi,
I use simH pretty often on my Next Thing Co CHIP, and have documented a
lot about it here and elsewhere on my web site
http://vintagecomputer.net/browse_thread.cfm?id=664
..these are things you all know probably very well already but I like to
document my work so I remember and avoid reinventing the wheel.
I have a question...I have a real PDP 11/40 with RL02 drives. I have been
able to port disk images made for the RL02 using PDPGUI onto the real
drives. I have RT11 running now. I believe I can run RSX11M v 3.2 on my
system if I can find a way to get it from RL01 images to RL02. My question
is ... Has anyone found a way to use simH to port disk images from RK05 or
RL01 to RL02?
Scenario:
1) Set up a 64K PDP 11/40 (like my actual system), attach two RL01's and
one RL02
2) Get the system running using the RL01 image of RSX11/M for example or
RK05 DOS/BATCH
3) Once it's working on simH dump or copy the RL01 disk to RL02, maybe
even merge two RL01's into one RL02.
4) Test in simH using the RL02(s)
5) Port disk to actual RL02 using PDPGUI.
Just curious if this has ever been done, I assume its not as simple as
copying say 5 1/4" disks to 3.5" in DOS, but maybe it's doable if you know
simH and the OS you're porting has flexibility. I would think back in the
DEC days this problem was solved. Maybe some OS's are better than others.
Maybe the trick is somehow copying the drivers to a blank target disk
first, then moving the files from the source minus the drive type drivers.
I am still learning, but I am at the point to ask what I hope is not an
overly uninformed question like this.
Bill Degnan
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Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: [email protected] || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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