On 05/04/11 15:47, Dalby, Jeremy R (GE Power & Water) wrote:
I am trying to figure out how to slow down the SIMH PDP-8 simulator such
that the instructions are executed with similar timing to that of a real
PDP-8. I have found that that even with throttling set very low, the
PDP-8 simulator executes much, much faster than a real PDP-8.
From what I have read, I believe the execution of a single PDP-8
instruction can take anywhere from 1.2 - 4.6 microseconds, depending on
the type of instruction and I/O device to which the instruction applies.
I am running the PDP-8 simulator on a Windows XP host, which I
unfortunately cannot change to a real-time environment.
Some things I have considered:
1. Inserting a sleep() function after execution of each PDP-8
instruction, but this won't work since the minimum sleep time is 1
millisecond, and even a 1 ms sleep request is not likely to return for
at least 20 ms due to Windows non-real-time scheduling.
Do you have to use a Windows host ? We use usleep() on Linux and its
normally accurate to 10% of the specified sleep interval. Thats on both
x86 workstations (Dell T3400 etc) and ARM (i.MX25) SOC's.
regards
---
Matthew J Fletcher
amimjf(at)sky.com
www.amimjf.org
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