[Simh] MOP header specs?

[Johnny Billquist]

On 2018-02-23 14:39, Timothe Litt wrote:
> You're asking for something that doesn't exist.
> 
> .SYS files can be anything.  When downloaded via MOP, can by any 
> architecure - not just the server's.
> 
> .SYS can be a pagefile.  Or a swapfile.  Or a pdp-11 task image.  Or a 
> standalone VAX image.  Or an accounting file.  Or 68000 code.  Or 8080 
> code.  Or Alpha code.  Or a bitmap destined for a graphics adapter.  Or 
> anything else.

Right. A .SYS file can be anything. It's just a name.
That said, the MOP server under RSX as well as VMS understands files 
with a specific format, and I suspect that might be what you actually 
are asking for. I don't know if there are any documentation about the 
file format that those MOP servers can handle. (Except reading the source.)

> There is no MOP header.  What you may be seeing, as I noted previously, 
> is a MOP secondary or tertiary loader.

I don't know what he was looking at, but if it was the beginning of the 
file, then there was nothing MOP about it at all.

> There are specs for each usage; e.g. what Johnny provided is a program 
> that decodes an RSX task image.  But it's not really an RSX image; in 
> his example, the RSX task builder was used to link 68000 code.  So the 
> secondary loader code, to be functional, would be 68000 code.

Right, in that my program decodes RSX task image headers. It just so 
happens that the image files DEC provided for DECservers are in the same 
format. However, I seriously doubt TKB was used to build those files. 
(But I could be wrong of course.)
But the thing is, the task image can be pretty much anything. The header 
only gives some basic information about sizes and addresses for the 
image, as well as some meta information such as name, build date, and 
similar stuff.
You're supposed to just place the rest of the file in memory, at the 
addresses given, and start off at the given start address. The image 
itself could be for any architecture or system. Don't matter for the 
task image itself.

> A VAX download would have a different image header, and VAX code. And so 
> on for ANY architecture.

True. But the file that I gave the output from is a DECserver image, 
which DEC provided, and which could be served from both RSX and VMS. So 
the MOP server on those two systems understand the same image format. It 
might be that the VMS MOP server might understand other file formats as 
well, I don't know.

> All MOP knows is to request a specific program; load bytes to an 
> address; and jump to an address.  Any interpretation of the bytes is up 
> to the code that's loaded - and the client CPU.

Right.

> That's why a MOP load normally consists of asking for a program - which 
> is the secondary loader.  It's the secondary (or tertiary) loader that 
> knows how to unpack an image and make additional requests.

Hum. Well, that might be, but both will be served through MOP, so it 
don't make much difference if it's the primary or secondary boot. They 
are served the same way. The receiving end might be doing more stuff at 
the secondary or tertiary boot loader, but from the serving side it's 
all the same.

> The file that you mentioned is Alpha SRM console code.  The only reason 
> for it to have a MOP loader is so that a firmware update can be done by 
> booting from a network repo.  I don't know if it was supported; the 
> usual path was LFU from a CDROM or disk.  Note that you can't boot (or 
> run a MOP client, or do much or anything) without the SRM console 
> already in FLASH.  (Or the NT ARC console.)  It's the firmware that 
> knows how to negotiate MOP, and it's the firmware that provides the 
> instructions implemented in PALcode.  So that path is not useful for 
> bare hardware.

Yup. The MOP client needs to already be on the system (obviously).

   Johnny

> 
> 
> On 23-Feb-18 07:53, Tim Stark wrote:
>> Johnny,
>>
>> Oh, I now got it.   I mean SYS specs, not MOP specs.  Is that TIN program available?
>>
>> Thanks,
>> Tim
>>
>> -----Original Message-----
>> From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Johnny Billquist
>> Sent: Friday, February 23, 2018 4:31 AM
>> To:simh at trailing-edge.com
>> Subject: Re: [Simh] MOP header specs?
>>
>> On 2018-02-21 04:13, Tim Stark wrote:
>>> Folks,
>>>
>>> Does anyone know any documentation provides some information about MOP
>>> header in SYS files?
>> MOP headers no. But if you are referring to the .SYS files DEC distributed for things like DEC servers, which booted over MOP, those SYS files look like "normal" task files in RSX. Task files linked with no task header, though.
>>
>> Example:
>> .tin sh1601ENG.SYS
>> TIN V1.7
>> Task name: SHAMRO Date: 21-MAY-96 Pri=0. Start=075000. EXTTSK=000000.
>> Label block revision: 0.
>> Task addresses - Low: 051000, W0 high: 177777, High: 177777 Load size: 02161400 Max size: 02161400 # of window blocks: 1.
>> Task flags (040100): -HD -CHK
>> Partition: SYSTEM Offset: 000000
>> System ID: RSX-11M.
>>
>>
>> TIN is a small program I wrote a long time ago to analyze task images under RSX.
>>
>> That file, for example, is for the DS300 (which has a 68000 CPU). And the RSX MOP server can service that file. VMS can serve it too. But this is totally outside the MOP protocol itself.
>>
>> The MOP protocol is documented in various places as well, so if you want that, you can find it. But the .SYS files are images that are served by MOP. They are not verbatim MOP data.
>>
>>     Johnny
>>
>>> 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
>>>
>>>
>>>
>>> _______________________________________________
>>> Simh mailing list
>>> Simh at trailing-edge.com
>>> http://mailman.trailing-edge.com/mailman/listinfo/simh
>>>
>>
> 
> 
> 
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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