Re: ZipGS strange slow-down

[rubywand@aol.com (RUBYWAND)]

In article <6JUL199604225960@vax2.concordia.ca>, spec@vax2.concordia.ca
(Mitchell Spector) writes:

>
>   I found this rather odd, with my ZipGS active (set to highest speed)
>I watched the animated introduction for Silpheed. Once it finished, I
>quit and loaded it a second time, but it ran noticably _slower_. I tried
>again and again, it continues to go much slower than it did the first 
>time. If power-down the IIgs, then launch the game, the intro returns
>to the speed it should, although the above repeats itself where loading
>it a second time slows it considerably.
>

     The slow-down may indicate that, somehow, the Speed register at $C036
is getting set to "Normal" speed (bit 7 is going to "0")  upon game exit.

     Another possibility is that, upon exit, Zip-GS Control Panel or Zip
CDA code is being accessed and diddling the Zip speed or ON/OFF setting.
Perhaps the game does an incorrect Quit.

     Anyway, after exiting, you might try going to the Control Panel after
the slow-down and setting Speed to "Fast" (even if it claims to be set at
"Fast").  You can also try accessing the Zip Control Panel and setting
Speed, etc..


>   My guess is the cache is not getting flushed, powering down the GS
>of course clears whatever was in there. Still, I find this occurance
>rather unusual. Is this _normal_ or is it just some oddity caused by
>Silpheed? I'm using a 15/64 ZipGS btw (I doubt this is another problem
>caused by a weak powersupply, though in any case that will be fixed
>in a matter of days).

     If your Zip-GS runs the game at full speed, it does not seem likely
that there is a problem with marking and accessing cache.

     Glitching is very common when running a fast Zip-GS (i.e speed is
above 9MHz) on a power supply with standard pissant leads. The PS may have
the capacity to deliver the needed current; but, the voltage drops in the
leads, the connector, and the Slot bus combine to reduce voltages,
decrease noise margins, and increase level of noise spikes on the +5 and
+12 rails.

     It may be that, upon exiting the game, the Zip-GS does a normal
slow-down when checking some Slots after starting the Finder. If one of
the Slot checks turns ON a device (like a diskette drive), the resulting
power spike could mess up Zip's return to full speed.