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 Robotics / RCX / 350
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Subject: 
Re: Speed of RCX interpreting bytecodes: slow
Newsgroups: 
lugnet.robotics.rcx
Date: 
Wed, 5 Jan 2000 00:03:11 GMT
Viewed: 
1441 times
  
In lugnet.robotics.rcx, Kekoa Proudfoot writes:
Ben Jackson <ben@ben.com> wrote:
While working on the barcode scanner I decided to see just how fast the
RCX could loop.  A simple NQC program can do about 1000 counter loop
iterations in about 100 ticks, or 1 iteration/ms.  This is shockingly
slow.  The native H8/329 is clocked at 16Mhz and claims to do simple adds
in 2 clocks...

What is in a "counter loop iteration" ?  Please share the NQC program you
used to measure this with us.  I fail to believe that a simple loop runs
this slow.  16000 cycles per loop iteration does not sound right to me.

From memory, the NQC was:

int count;

task main()
{
count = 0;
CreateDatalog(100);
ClearTimer(Timer(0));
while (count <= 1024) {
if (count & 0xff == 0)
AddToDatalog(Timer(0));
count += 1;
}
}

The downloaded datalog will show the last log entry at around 100.  You could
simplify this (just log one timer entry) but no matter how you slice it it's
VERY slow.

--Ben



Message is in Reply To:
  Re: Speed of RCX interpreting bytecodes: slow
 
(...) What is in a "counter loop iteration" ? Please share the NQC program you used to measure this with us. I fail to believe that a simple loop runs this slow. 16000 cycles per loop iteration does not sound right to me. -Kekoa (25 years ago, 4-Jan-00, to lugnet.robotics.rcx)

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