[Simh] RP/RM differences in header commands (for ITS, salvager)

[Johnny Billquist]

On 2019-06-28 00:59, Rob Doyle wrote:
> On 6/26/2019 9:54 PM, Lars Brinkhoff wrote:
>> SALV actually writes data for an entire track all in one go.  I tried
>> something which skips the headers in the middie.  But there must be
>> something else wrong with my code, because when reading back the sector
>> data I just get zeroes.
>>
>> Anway, I agree something like that would go most of the way to make SALV
>> happy.  There's another part of SALV that reads the header information
>> go access the pack number written there, but I'm not sure how that
>> number is used later.
> 
> I think that should work. When executing the "write header plus data"
> command, the state machine in my FPGA's RP06 controller just handles the
> first two 36-bit words (technically four 16-bit words) specially and
> jumps to the "write data only" states to transfer the non-header data.
> Ditto read and write check commands.

Sounds like what I'm advocating.

> This part of the FPGA passes all of the RP06 diagnostics - so I believe
> it is correct.

That is really interesting to hear.

>  From a hardware point of view, sector header "Word 3" and "Word 4" have
> no particular meaning.  Just for completeness, can you point me to a
> reference where "pack number" is defined or used by the software?

Search for DEC standard 144. If nothing else, I think there is a 
description in the RL11 documentation. (Me trusting my memory once more...)

   Johnny

-- 
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