[Simh] porting RL01 images to RL02

[Johnny Billquist]

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: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol