[Simh] VAX 8200

[Mark Pizzolato]

The programmatic method Rick provided (and Tim suggested enhancements to) is perfect when you’ve got a working system that has the necessary pieces to run VMS.

Meanwhile, there may be systems which no longer have enough working pieces to actually run any program to extract the ROM contents, or the only OS they have access to on local storage isn’t VMS.

As long as the system runs well enough to get to the >>> prompt on the system console, the console itself can be used to extract the ROM contents.  For example, the MicroVAX 3900’s ROM is at 20040000 and is 128Kb (0x20000) in length (which is 0x8000 Longwords).

To display the whole ROM contents from the console prompt:

          >>> E /N:7FFF 20040000
             P 20040000 FE112211
             P 20040004 01530302
             P 20040008 00038931
           […]
             P 2005FFF8 00000000
             P 2005FFFC 00000000
          >>>

Capturing the console session’s content and manipulating the captured text into a binary ROM image is left as a programming exercise.

Some systems may not have the /N:nnn option in the console command language.   Those would be reduced to explicit E commands for each longword of the ROM:

          >>>E 20040000
             P 20040000 FE112211
          >>>e
             P 20040004 01530302
          >>>e
             P 20040008 00038931
   Etc…




-          Mark

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Timothe Litt
Sent: Sunday, March 19, 2017 4:39 AM
To: simh at trailing-edge.com
Subject: Re: [Simh] VAX 8200


Don't be discouraged from posting.  Nothing wrong with a quick hack.  They do tend to have a longer than intended life, and considering the range of experience on the list, I thought it worth taking a couple of minutes to suggest a more robust implementation.

I did restrain myself and did not point out how to provide command line arguments (foreign or DCL command table), create a VMS help file, internationalize messages or build a VMSINSTAL (or PCSI) kit :-) It is, after all, a QUICK hack...

Later hardware uses FLASH parts, which aren't socketed (well, very rarely), so even for people who have the hardware skills to remove ROMs, there's a future use for a utility.  Plus, it works in simulation :-)


On 18-Mar-17 21:01, Rick Murphy wrote:

On 3/18/2017 12:23 PM, Timothe Litt wrote:


Even though someone found a utility for the 8200, a program like this is handy for other machines (and device roms).

A good outline of the essentials of PFN (and file) mapping, but for general use...
Timothe, well spotted (I actually noticed the lack of $close when posted, and said, oh well... it does the job.)
However, remind me to never post any quick hack here ever again. :)

This was used to pull an image of the ROM, initially to probe the code with VMS PATCH, eventually to dupe the ROM. In the end, it was easier to just pull the ROMs and duplicate them.
    -Rick

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