[Simh] vax780 bare metal - rq addresses --> rq registers

[Johnny Billquist]

It's a little complicated, because the controller is on the Unibus, and 
the Unibus only have an 18-bit address space.
So the SBI Unibus adapter contains a mapping between the VAX address 
space, and the Unibus address space, and the UBA also contains mapping 
for DMA, which must be set up before playing around. So there are layers 
you need to go through.

Also, the MSCP controllers only actually have two registers on the bus, 
and they are only really used for anything more advanced than just 
getting the attention of the controller at initialization. After that, 
all communication happens through buffers.

   Johnny

On 2020-05-14 02:14, Mike Stramba wrote:
> What is the relationship / mapping between the addresses displayed
> for the SHOW RQ  (disk controller) command and the listed registers in the
> vax780 manual ?
> 
> E.g  SA, S1DAT, CQBA etc ?
> 
> i.e. Does the SA register appear  /  is accessed at 2013F468 ?
> 
> S1DAT at 2013F46A  .... etc ?
> 
> If so, are those addresses not accessible with EXamine / Deposit ?
> 
> sim> ex 2013F468
> Address space exceeded
> 
> Only from an instruction ?  :
> 
> e.g.
> 
> MOVW R0,2013F468
> 
> sh rq
> RQ	address=2013F468-2013F46B, vector=1FC*, BR5, UDA50, 4 units
> .....
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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