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From: rico@oscvax.UUCP
Newsgroups: net.micro.amiga
Subject: Re: Fraud And Deceit (I'm mad as hell)
Message-ID: <435@oscvax.UUCP>
Date: Sun, 13-Jul-86 15:32:36 EDT
Article-I.D.: oscvax.435
Posted: Sun Jul 13 15:32:36 1986
Date-Received: Sun, 13-Jul-86 19:18:59 EDT
References: <1353@well.UUCP> <1811@shark.UUCP> <567@3comvax.UUCP> <1400@well.UUCP> <1391@amiga.amiga.UUCP> <737@Navajo.ARPA>
Reply-To: rico@oscvax.UUCP (Rico Mariani)
Organization: Ontario Science Centre, Toronto
Lines: 61
Keywords: Comspec, Dhrystone,  Memory
Summary: 'Fast' ram is only 1% slower

In article <737@Navajo.ARPA> rokicki@Navajo.UUCP writes:
>
>I've got one of those CardCo boards, and yes, it does slow the machine
>down something awful.  Here are the stats:
>
>	512K machine, 1.1		988 dhrystones
>	1536K machine, 1.1		674 dhrystones
>		Loss			 31.8%
>	512K machine, 1.2 beta II	983 dhrystones
>	1536K machine, 1.2 beta II	664 dhrystones
>		Loss			 32.5%
>
>Which means I just paid so many hundreds of dollars to SLOW DOWN MY
>MACHINE!  Now, I've designed memory boards before; it's not that
>difficult to make the RAM run with no wait states on a 7.2 MHz
>machine.  To slow it down so much seems to indicate that two wait
>states are being introduced for EVERY MEMORY REFERENCE!  This
>is inexcusable.

FYI, I ran the same tests on my Amiga with a Comspec memory board and
the results were much more encouraging.  I only ran the tests once
each (OK so I'm lazy... gimme a break) so there is some variance
compared to the above figures on an unexpanded Amiga.  I used 50000
cycles with no registers on Manx Aztec C with 16 bit integers.  The
times were collected with my little brother's watch in stopwatch mode.
The numbers below have lots of digits after the decimal but I wouldn't
really trust them too much.  I've also included the actual time that I
measured for 50000 cycles.


    512K machine, 1.1		975.04 dhrys/sec = 51.28 secs for 50000 cycles
    2.5M machine, 1.1		967.49 dhrys/sec = 51.68 secs for 50000 cycles
    Comparison:  99.23% of top speed = 0.77% Loss

    512K machine, 1.2 Beta II	976.56 dhrys/sec = 51.20 secs for 50000 cycles
    2.5M machine, 1.2 Beta II	963.58 dhrys/sec = 51.89 secs for 50000 cycles
    Comparison:  98.67% of top speed = 1.33% Loss

As you can see, the times are close enough to each other that the stopwatch
method really isn't accurate enough to get a  good figure for the difference.
This should be good enough for the purpose of this experiment though.

Another FYI, the Comspec board uses 500mA in typical (not idle) operation.
Remember that's a 2 meg board...  I can't tell you too much about the
ground plane and such but it passes the "I can't see thru the PC board"
test.  Then again, maybe the light I was using wasn't bright enough :-)


DISCLAIMER: a) The Science Centre doesn't have anything to do with any of this.
	       Leave them alone!

	    b) I've enjoyed a healthy relationship with Comspec for a long
	       time now so my views may or may not be biased because of this.

	    c) I don't know what I'm talking about at the best of times :-)


	That's all
	  -Rico

		...{allegra|ihnp4|decvax|watmath|linus}!utzoo!oscvax!rico