Some PDP11 related Questions.. - test-drb@ccmp.vtda.org

25 Jan 2012

On 2012-01-25 19:00, Holm Tiffe<holm at freibergnet.de> wrote:
...
  allison wrote:

  >  On 01/25/2012 06:40 AM, Holm Tiffe wrote:
> >  >Hi,
> >  >
> >  >I have A M8186 (KDF11-A Rev D) and an M8047-CA (MXV11-AC) currently in
> >  >an H9275 Backplane.
> >  >I've fiddeled around an wondering why I can't access the ROMs on
the M8047
> >  >at 173000. Finally found it, they get active ad 773000 in the ODT, since
> >  >the M8047 is using the BBS7 Signal from the CPU to decode the ROM Address.
> >  >My question is now regarding the Bootstrap setting, the Manual says that
in
> >  >ODT mode the BDAL16 and BDAL17 are enabled to get access to the higher
> >  >memory contents. How is this handeled while bootstrapping? I can't set
a
> >  >bootstrap address of 773000 on the KDF11, it boots now in ODT Mode and
> >  >displays 173000 after Reset, thati's the jumpered address.
> >  >How is this (BBS7) handeled while bootstrapping? Is the BBS7 low while
> >  >bootstrap at 173000 or is the M8047 incompatible with this processor?
> >  >(I've not tested to bootstrap since I don't know what is in the
ROMs and I
> >  >don't have an RX02 nor TU58 to connect, want to put in a M7555 so I
have to
> >  >change the ROMs for sure). As far as I know this KDF11 should be able to
> >  >handle 22 bits (420HD0 on the Handle, 5013326 D-P4 on the Board) is that
> >  >the case?
 >
 >  Most all KDf11s are Q22 make sure both of the hybrid chips are there the
 >  second
 >  one has the MMU for the 22 bit mapping!
 >
 >  Also make sure the backplane is Q22.
 >
 >  Lastly the M8047 make sure its jumpered correctly.  If the boot in it
 >  fails due to lack of device I think the report is 173003?.
 >
 >  ODT only knows 16bit octal.  And BBS-7 is activated when the upper three
 >  address bits are active for addresses greater than 160000 which is IO
 >  and boot address space.  Yes, but I mean the difference between 773000 vs
173000.
 I see the ROMs in ODT at 773000 but not at 173000!
 Anyway, I'll jumpering the CPU to bootstrap and will look what happens. 
Here is how it actually works:
When the CPU is addressing anything in memory, it goes through the MMU. 
Always. However, the MMU can act in three different modes.
16-bit
18-bit
22-bit

In 22-bit mode, all CPU accesses are virtual addresses, and they get 
translated by the MMU into other 22-bit addresses. Pretty straight forward.
In 18-bit mode, all CPU accesses are also virtual addresses, and they 
get translated by the MMU into 22-bit addresses. Only part of the PAR 
registers are used. However, memory access to addresses in the high 4kW 
are mapped to the high end of the 22-bit address range, even though you 
only have 18-bit addresses.
In 16-bit mode, all CPU accesses are physical addresses. However, the 
MMU recognize addresses in the high 4kW of the address space, and move 
those accesses to the high 4kW of the 22-bit address space.

Next is the BBS-7 signal, which is active if the physical address then 
is above 17760000. Anything in the I/O page should never decode the 
A21-A13. BBS-7 will be the logical AND of A21-A13.
In fact, it might be that BBS-7 is shortcircuited inside the MMU, and 
the MMU don't even drive A21-A13 when you are in 16-bit or 18-bit mode.

Anyway, the ROMs are *not* at 173000, if you talk about 22-bit or 18-bit 
addresses. They are at 173000 if you talk about 16-bit addresses only. 
In short, they are at address 13000 in the I/O page. Wherever your I/O 
page is. If you enable 22-bit addressing, and put the I/O page at page 
0, the ROM memory will appear at virtual address 13000, really.

I hope this makes things clear. Otherwise feel free to ask. It's really 
not that complicated.

...
  > > 
>Next question about RAMs: I do have some QBUS Memory boards with PMI
> >  >connectors (M6708, NatSemi NS638, Chrislin CI-MV8 to be concrete) does
> >  >anyone know if I can use one of them with the KDF11 (or at least the
> >  >KDJ11?) I hve a KA630 too, but I need PDP11 RAM, the 16KW on the M8047
> >  >is really a bit small....
> >  >
 >  PMI can be used with KDJ11 if its the right PMI.  KA630 is not PDP11 but it
 >  is microVAX.  Yes, know this. But what's the right PMI for the KDJ11?
 I have soldered an additional Megabyte to the KDJ11 and it has now 1,5MB,
 which is enough tu run 2.11BSD, therefore I don't have tried to use one of
 the memory Boards additionally until now. 
No. It is not compatible.
The PMI memory for VAXen does not work the same way as PMI memory for 
PDP-11s (even those that do have PMI memory).
VAX PMI uses a flat cable between the CPU and the memory boards. PDP-11 
PMI memory uses signals in the CD slots to communicate with PMI memory.
In addition, for VAXen, PMI is used to be able to address more than 4 MB 
as well as speed, while on the PDP-11 PMI memory only have PMI for the 
speed gains, as a PDP-11 cannot address more than 4 MB anyway.

Also, the PDP-11 PMI memories works just fine as any normal Qbus memory. 
It only acts as PMI memory under some specific circumstances, else it's 
just normal Qbus memory. VAX PMI memory does not work as normal Qbus 
memory under any circumstances, as far as I know.

If you want the designation for the KDJ11 PMI memories, just search 
through the field guide that is on the internet.

	Johnny

-- 
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