25 Jan
2012
25 Jan
'12
1:43 p.m.
On 25/01/2012 19:03, Holm Tiffe wrote:
Aha. So it is haindled differently under program control as in the ODT Mode.
That was my question.
In a way, yes, but in a way, no. The CPU always asserts BBS7 when
addressing the topmost 8KB of memory space; it's just that the 16-bit
CPU has a 64KB logical memory space whereas the MMU-equipped device has
a larger logical space. And then to complicate matters, but only for
that F11 processor, ODT is hardwired to 18 bits (other 22-bit CPUs also
have 22-bit ODT).
I know that is a "real" serpentine QBUS
Backplane.
Yes, but the downside is that being serpentine means certain quad-wide
cards can't be used. Anything that uses CD as CD interconnect, or that
puts unusual connections on those connectors.
I have a H9278 too, currently the KDJ11 is in there.
Maybe I should use it
for the KA630 VAX in conjunction with the memory Boards since it has 3 CD
private Slots.
That backplane is meant for a BA23 box, the type used for small
microPDP-11 and microVAX systems. Which makes sense if you have an
M7554, which is the CPU for a microPDP-11/53 -- one of the smallest and
the slowest J11-based microPDP-11 systems ever made.
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.
Not quiet, on a KDF11-A ODT is 18-bit. Under program control, the CPU
uses BBS7 to address the I/O page regardless of high-order address bits. Yes. I've asked primarly since I have those 3 CPU
Boards, The VAX, The
KDJ11 (later version with onboard RAM) and the KDF11 with 2 Hybrids and
the MMU. (one socket free).
What about the RAM Boards and the KDJ11? I found no documentation for the
7608 ant nothing again for the other Boards (Crislin and NS).
Is one of them usable for the KDJ11 or is this VAX RAM different to the PMI
RAM for the KDJ11?
As others have already explained, the microVAX memory is completely
incompatible with a PDP-11. The NS638 is definitely microVAX memory,
ditto M7608 (it's an MS630), but I don't know about the Crislin. If it
has the connector on the end for the ribbon cable to connect memory to a
microVAX CPU, it's microVAX memory; if it doesn't have that, it isn't :-)
It was quite unusual to have additional memory cards in a
microPDP-11/53, because it was designed to be a low-cost all-in-one
processor/SLU/memory/bootstrap/clock board.
--
Pete