16 Dec
2003
16 Dec
'03
4:16 a.m.
On Dec 15, 22:42, Jerome H. Fine wrote:
even
So, taking the M8190-AB as baseline, and doing some arithmetic:
M8190-AB M8190-AE
15MHz 18MHz
non-PMI 1.0 1.1
PMI memory 1.3 1.5
18MHz is 1.2 times 15MHz, so it seems other operations on the bus
are reducing the effect of the clock speed increase. Of course, that
might also be due to using memory with a different cycle time. Still,
it's clear that the PMI makes a bigger difference than the clock speed,
going from 15MHz to 18MHz.
--
Pete Peter Turnbull
Network Manager
University of York
Pete Turnbull
wrote:
> Yes, because that's about the only useful distinction -- the speed
> increase brought by PMI memory is more than the clock difference
> between 15MHz and 18MHz -- and of course if placed after the CPU, a PMI-capable
memory board operates as normal Q-Bus memory.
Approximate speed increase from M8190-AB (KDJ11-BB)
with normal DEC memory (obviously below the CPU) vs
M8190-AE (KDJ11-BF) with DEC PMI memory above
the CPU was about 33%. An assembly which took about
4.5 minutes was reduced to about 3 minutes. I can't recall
the exact numbers or exactly what I tried, but the test with
the M8190-AB and the PMI memory above the CPU took
about 23% less time than 4.5 minutes. I then tried the
M8190-AE and normal DEC memory below the CPU
and that took about 10% less time than 4.5 minutes. When
the PMI memory was below the M8190-AE, that also
took about 10% less than the 4.5 minutes. 
16 Dec
16 Dec
3:02 p.m.
Pete Turnbull wrote:
Jerome Fine replies:
YEP!!!
Of course, starting from a base of 1.0 with the M8190-AB, the
percentage is higher, but that is just the aspect of a reciprocal.
The other speed I found is that a PDP-11/93 is only about 10%
faster than the ( M8190-AE / PMI ) pair. So at the time that
the cost of PMI memory fell to its lowest, just switching memory
was the best solution.
But I also like the solution Megan Gentry suggested - change
the crystal on the M8190-AE to 20 MHz and see if it works.
But since that solution is 10 times more difficult for me than
using a 750 MHz Pentium III which has a speed factor of
about 15.0 (OK it is not that great for the CPU which might
be as low as 10.0 or just a 1000% factor, but overall when
the disk I/O is included is still probably 15.0 or 1500%),
I tend to stay with the Pentium III solution which does not
involve a soldering iron. In addition, using a 3.0 GHz P4
should allow for a factor above 50, maybe as high as 100.
I agree I don't hear those fans and disk drives of 250
GigaBytes can be standard (although under RT-11 I have
a hard time using an emulated drive of more than 2 GBytes),
but I guess I will have to grin and bear the difficulty.
Notice that I am not saying that you hardware addicts are
wrong and that me as a software addict is right - we each
have our own niche. In fact, I am beginning to really think
I must be crazy to want to make a Y10K version of RT-11
which I am almost sure no one will ever use - including ME!
But at least I will probably get to do things 100 times faster.
Sincerely yours,
Jerome Fine
--
If you attempted to send a reply and the original e-mail
address has been discontinued due a high volume of junk
e-mail, then the semi-permanent e-mail address can be
obtained by replacing the four characters preceding the
'at' with the four digits of the current year.
On Dec 15,
22:42, Jerome H. Fine wrote:
Approximate speed increase from M8190-AB (KDJ11-BB)
with normal DEC memory (obviously below the CPU) vs
M8190-AE (KDJ11-BF) with DEC PMI memory above
the CPU was about 33%. An assembly which took about
4.5 minutes was reduced to about 3 minutes. I can't recall
the exact numbers or exactly what I tried, but the test with
the M8190-AB and the PMI memory above the CPU took
about 23% less time than 4.5 minutes. I then tried the
M8190-AE and normal DEC memory below the CPU
and that took about 10% less time than 4.5 minutes. When
the PMI memory was below the M8190-AE, that also
took about 10% less than the 4.5 minutes.
So, taking the M8190-AB as baseline, and
doing some arithmetic:
M8190-AB M8190-AE
15MHz 18MHz
non-PMI 1.0 1.1
PMI memory 1.3 1.5
18MHz is 1.2 times 15MHz, so it seems other operations on the bus
are reducing the effect of the clock speed increase. Of course, that
might also be due to using memory with a different cycle time. Still,
it's clear that the PMI makes a bigger difference than the clock speed,
going from 15MHz to 18MHz.
7677
days inactive
7677
days old
1 comments
2 participants
participants (2)
-
jhfinexgs2＠compsys.to -
pete＠dunnington.u-net.com