10 Feb
2016
10 Feb
'16
12:05 p.m.
Richard Cini wrote:
Jerome -- good point about the IOPAGE. Maybe I'll
get an 8kw and 16kw board -- that gives me 28kw with the included 4kw. I have no specific
software so I don't need to tinker with reducing IOPAGE.
Rich
>>On Feb 9, 2016, at 10:47 PM, Jerome H. Fine <jhfinedp3k at compsys.to>
wrote:
>
>>Thanks guys. This is really helpful. I was getting confused between the M8044 and
M7944 boards. Max memory for the LSI-11 is 32kw, right?
>>
>>
>Correct, the maximum memory on a board is 32kw.
>
>For an LSI-11 (aka PDP-11/03) without any MMU hardware,
>the actual maximum memory that can be accessed must also allow
>for the IOPAGE registers. Usually, the IOPAGE address range
>is 4 kw which leaves 28kw for everything else, including RT-11
>(assuming that is what you are running). There is one option
>available with some hardware to reduce the address range
>set aside for the IOPAGE to just 2kw which then leaves
>30kw for everything else. Unless you are running a specific
>program which requires the extra 2kw, it is probably not
>worth the extra effort.
>
I hope that my version of arithmetic is for 8kw + 16kw = 24kw,
so somewhere I don't understand where the other 4kw comes
from.
Then, since you are missing only 4kw out of the maximum of
28kw (which is the normal maximum), you will not likely have
a problem unless you have really memory rich programs.
RT-11 runs fairly well in just 16kw (or 32 KB), so it should not be a
problem. For my own work in which I need to run MACRO.SAV
as fast as possible, I run the program in 64 KB of extended memory
under a Mapped Monitor - which a PDP-11/03 (or an LSI-11)
can't do since there is no MMU chip.
Of course, my actual CPU is a Pentium III which I use to run Ersatz-11
so that RT-11 is running 15 times as fast as a PDP-11/93. And the
disk I/O is also a bit faster. I can copy a 32 MB RT-11 partition to
a second 32 MB RT-11 partition in under 2 seconds. Even with two
ESDI hard drives on a PDP-11/93, that takes over 4 minutes.
Jerome Fine
10 Feb
10 Feb
12:24 p.m.
Jerome -- it's "new math" :-)
Seriously though, I guess I could have been a bit clearer in my description, but think I
had mentioned somewhere along the way that the unit already had 4kw of memory, so I was
trying to get to 28kw to leave IOPAGE open. I also just realized that the boards have a
"page 7 disable" which operated like the S100 "phantom" signal which
is why a 32kw board would work. Learning lots during this process. Everything I forgot
about my 11/34a is starting to come back.
Sent from my iPhone
On Feb 10, 2016, at 3:05 PM, Jerome H. Fine
<jhfinedp3k at compsys.to> wrote:
Richard Cini wrote:
Jerome -- good point about the IOPAGE. Maybe
I'll get an 8kw and 16kw board -- that gives me 28kw with the included 4kw. I have no
specific software so I don't need to tinker with reducing IOPAGE.
Rich
>>> On Feb 9, 2016, at 10:47 PM, Jerome H. Fine <jhfinedp3k at compsys.to>
wrote:
>>
>> Thanks guys. This is really helpful. I was getting confused between the M8044 and
M7944 boards. Max memory for the LSI-11 is 32kw, right?
> Correct, the maximum memory on a board is 32kw.
>
> For an LSI-11 (aka PDP-11/03) without any MMU hardware,
> the actual maximum memory that can be accessed must also allow
> for the IOPAGE registers. Usually, the IOPAGE address range
> is 4 kw which leaves 28kw for everything else, including RT-11
> (assuming that is what you are running). There is one option
> available with some hardware to reduce the address range
> set aside for the IOPAGE to just 2kw which then leaves
> 30kw for everything else. Unless you are running a specific
> program which requires the extra 2kw, it is probably not
> worth the extra effort.
I hope that my version of arithmetic is for 8kw + 16kw
= 24kw,
so somewhere I don't understand where the other 4kw comes
from.
Then, since you are missing only 4kw out of the maximum of
28kw (which is the normal maximum), you will not likely have
a problem unless you have really memory rich programs.
RT-11 runs fairly well in just 16kw (or 32 KB), so it should not be a
problem. For my own work in which I need to run MACRO.SAV
as fast as possible, I run the program in 64 KB of extended memory
under a Mapped Monitor - which a PDP-11/03 (or an LSI-11)
can't do since there is no MMU chip.
Of course, my actual CPU is a Pentium III which I use to run Ersatz-11
so that RT-11 is running 15 times as fast as a PDP-11/93. And the
disk I/O is also a bit faster. I can copy a 32 MB RT-11 partition to
a second 32 MB RT-11 partition in under 2 seconds. Even with two
ESDI hard drives on a PDP-11/93, that takes over 4 minutes.
Jerome Fine
3190
days inactive
3190
days old
1 comments
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jhfinedp3k＠compsys.to -
rich.cini＠verizon.net