[Simh] MOP header specs?

[Timothe Litt]

On 21-Feb-18 09:32, Paul Koning wrote:
> MOP is a protocol, not a storage spec.  The protocol is defined in
> detail, in the MOP architecture spec, which can be found in various
> collections of DECnet architecture specs.
>
Yes
> I assume a SYS file is a file meant to be downloaded by a MOP server
> on some host.  What the file contents means depends on what the sender
> and/or receiver do with that data; the MOP protocol spec has no
> opinion about it.  So the question actually becomes: what do the MOP
> server on OS x, and/or the MOP client on hardware or OS y, expect to
> see in the header of the file used for MOP request z?
>
Yes.
.SYS is a common extension for files loaded by MOP, though it has other
uses in the DEC multiverse.  I've seen it used for PDP-11 code; for
68000 code (used in terminal servers); for VAX code.

MOP load often gets you a secondary loader, which is capable of
multi-block loads.  And that usually loads a tertiary loader, which can
interpret an image file format.  But this is all architecture specific. 
The server knows nothing about it - it serves bits.  The bits are
specified with NML (NCP) in the MOP load database. The PDP-11 boot
architecture is an appendix in the MOP spec.  But it's not mandatory,
and other clients can (and do) vary.

The client gets whatever bits are sent & executes them.  Well, it's
expected to.  MOP could be used to load a bitmap into a graphics buffer
- it takes bits and puts them into memory.  After that, it's up to the
client.

Tim would do better to tell us the full filename, where he found it, and
what he's trying to do.

A8 might be an offset in a VAX image header, and the rest look like the
IDENT and other fields of a header, but I don't have a reference handy. 
Analyze/Image should confirm that.  And 'file' on *ix is pretty good at
identifying a file format. 

It's not a PDP11 boot block, which usually begins with 0240 (NOP).

Beyond that, I'm not inclined to play a guessing game. 

> paul
>
>> On Feb 20, 2018, at 10:13 PM, Tim Stark <fsword007 at gmail.com
>> <mailto:fsword007 at gmail.com>> wrote:
>>
>> Folks,
>>  
>> Does anyone know any documentation provides some information about
>> MOP header in SYS files?
>>  
>> Look at first 256 bytes of SYS files:
>>  
>> 00000000: A8 00 30 00 44 00 58 00-00 00 00 00 30 32 30 35 
>> |..0.D.X.....0205|
>> 00000010: 01 01 00 00 FF FF FF FF-FF FF FF FF 00 00 00 00 
>> |................|
>> 00000020: 20 00 00 01 00 00 00 00-00 00 00 00 00 00 00 00  |
>> ...............|
>> 00000030: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 
>> |................|
>> 00000040: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 
>> |................|
>> 00000050: 00 00 00 00 00 00 00 00-03 4D 4F 50 00 00 00 00 
>> |.........MOP....|
>> 00000060: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 
>> |................|
>> 00000070: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 
>> |................|
>> 00000080: 04 56 31 2E 30 00 00 00-00 00 00 00 00 00 00 00 
>> |.V1.0...........|
>> 00000090: 00 00 00 00 00 00 00 00-05 30 35 2D 30 35 00 00 
>> |.........05-05..|
>> 000000A0: 00 00 00 00 00 00 00 00-10 00 87 15 00 00 00 00 
>> |................|
>> 000000B0: 80 00 00 00 02 00 00 00-00 00 FF FF FF FF FF FF 
>> |................|
>> 000000C0: FF FF FF FF FF FF FF FF-FF FF FF FF FF FF FF FF 
>> |................|
>> 000000D0: FF FF FF FF FF FF FF FF-FF FF FF FF FF FF FF FF 
>> |................|
>> 000000E0: FF FF FF FF FF FF FF FF-FF FF FF FF FF FF FF FF 
>> |................|
>> 000000F0: FF FF FF FF FF FF FF FF-FF FF FF FF FF FF FF FF 
>> |................|
>>  
>> Thanks,
>> Tim
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>
>
>
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