27 Oct
2015
27 Oct
'15
2:11 p.m.
From: Ben Sinclair
I'm trying to get my RLV11 working
Oh, I was going to mention this about the RLV11 - it's a Q18 device. So it
_probably_ won't work in a system with more than 256KB of memory (which you
don't, at this point, have, though). It would all depend on the OS, whether
it understood that it couldn't DMA to anywhere above 256KB. (The controller
should work OK in a Q22 system - it just won't drive the high address lines,
so they will go to 0 - but it just won't be able to DMA to high memory.)
I have a PDP-11/23 in an H9273 backplane. I just got
it working
reliably without the RLV11 boards installed ...
Here's my configuration:
Down the left side: M8186, M8044, M8044, M8043, M8013, M8014, and
M8012 (the BDV11) on the bottom.
Here's something to try (to make sure the 8013 is passing grants OK); put the
M8013/14 _before_ the M8043, and see if a test which uses interrupts on the
DLV11J works.
I also looked at myself and get 005737, though
I'm not sure what
it should be.
I take it "17440" is a typo for '174400'? Anyway, neither would work:
in
11/23 ODT, '174400' is the address of a word of memory, up near the 64K
boundary. To get to the device registers, you need to type '774400'. If that
doesn't work, the addressing on the RL11 board-set is wrong somehow.
Noel
PS: Speaking of typing addresses to ODT - My favourite pet 11/23 peeve: there
is no way, from ODT, to read/write memory above 256KB! That can only by done
by a program! (The 11/73 does not suffer this issue.)
28 Oct
28 Oct
9:29 a.m.
Noel Chiappa wrote:
From: Ben
Sinclair
I'm trying to get my RLV11 working
Oh, I was going to mention this about the RLV11 - it's a Q18 device. So it
_probably_ won't work in a system with more than 256KB of memory (which you
don't, at this point, have, though). It would all depend on the OS, whether
it understood that it couldn't DMA to anywhere above 256KB. (The controller
should work OK in a Q22 system - it just won't drive the high address lines,
so they will go to 0 - but it just won't be able to DMA to high memory.)
9:15 a.m.
Hi Jerome, thanks for the info!
According to the Microcomputer Interfaces Handbook, my H9273 backplane
should be all ABCD. Am I correct in that I shouldn't have any problem
using the RLV11 in that backplane?
On Wed, Oct 28, 2015 at 11:29 AM, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
The rest of Noel's reply agrees with my information, so
I will not comment.
However, just to place another option on the table, here
is that option which I observed around 20 years ago.
I was looking at some PDP-11 hardware in a BA23 box
and I noticed it had an RLV11 in slots 2 and 3. For those
of you who don't know the details, the first 3 slots are
ABCD and the other 5 slots are ABAB. Of course, all
of the slots in a BA23 box are Q22.
The key point is that an RLV11 MUST be placed into
a pair of ABCD slots, probably adjacent. Since the
CPU board in this example was in slot 1 in the BA23
box, there were only 2 ABCD slots available in any
case. NOTE that placing an RLV11 in two ABAB
slots will probably ALWAYS result in a release of the
magic smoke which activates all computer boards (at
least it did when I performed the experiment).
One key point to understand is that although the RLV11
can't perform DMA to memory above 256 KB, that
does not mean that the system can't have more than
256 KB of physical memory.
If there is anything that I have omitted by way of a
full explanation, please ask.
Jerome Fine
--
Ben Sinclair
ben at bensinclair.com
Noel Chiappa
wrote:
From: Ben
Sinclair
I'm trying to get my RLV11 working
Oh, I was going to mention this about the RLV11 - it's a Q18 device. So it
_probably_ won't work in a system with more than 256KB of memory (which
you
don't, at this point, have, though). It would all depend on the OS,
whether
it understood that it couldn't DMA to anywhere above 256KB. (The
controller
should work OK in a Q22 system - it just won't drive the high address
lines,
so they will go to 0 - but it just won't be able to DMA to high memory.)
3126
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ben＠bensinclair.com -
jhfinedp3k＠compsys.to -
jnc＠mercury.lcs.mit.edu