From: kanefsky@halcyon.com (Steve Kanefsky)
Subject: Re: Disk Cache size  (was Re: Speeding up graphics on a IIsi)
Organization: The 23:00 News and Mail Service
Date: Mon, 28 Sep 1992 20:32:46 GMT

In article <19qolqINN949@aludra.usc.edu> cokin@aludra.usc.edu (Darren Cokin) writes:
>In article <1992Sep23.184855.3408@u.washington.edu> iho@cac.washington.edu writes:
>
>>Before you spend a penny on anything.  Try setting the disk cache size
>>to about 256K.
>
>
>Will that really help speed up graphics?  Would it increase the frame rate
>in Hellcats, or make scrolling quicker in QuickGif?  I've got an LC, and I
>never changed the cache from the default 128k because I wasn't really sure
>what it would do, and I don't have much ram to spare.  But if increasing it
>will make things faster, let me know, and by how much.  Thanks.

The cache-size trick is only for the IIsi or IIci, which use 
regular DRAM for the built-in video.  The LC and LC II (among
others) use dedicated VRAM.

The idea behind the cache trick is to ensure that the application 
(a game in this case) isn't competing with the built-in video for
RAM access. Different banks of RAM are accessed independently, so
only memory in the 1MB of RAM which is soldered onto the     
motherboard competes with the built-in video (on the IIci, the 1MB    
isn't soldered on, so if you replace the 256K SIMMS you might 
have to use up to 64MB to avoid contention!) Setting the 
disk cache to a sufficiently-high value fills up the 1MB and   
ensures that the application gets loaded into the other bank of
RAM.  Of course, the disk cache itself is then contending with   
video for RAM access, but even slow RAM is a heck of a lot faster
than a hard disk.


Regarding the original poster's question about speeding up his 
IIsi:  If you don't need extra graphics capabilities (i.e. more  
than 8 bits per pixel or a big-screen monitor), don't buy a video
card.  You'd be much better off getting an accelerator card which  
will speed up every aspect of your IIsi's operation -- not just the
video.  At the low end, you could just get a cache card with 32K or
so of fast RAM for a few hundred bucks (at most).  A better choice  
would be a combination cache/accelerator card with a faster CPU and
optionally an FPU as well.  The Daystar PowerCache cards are, IMHO,
the best around.  They're 100% compatible with everything and   
they'll double or triple the speed of your IIsi in all areas.  I
added one to my LC II and it's faster than a IIfx now.  Game   
performance improved tremendously (i.e. they no longer bog down
when there's a lot of action on the screen or a lot of INITs running 
in the background).  I got the 50mhz 68030 PowerCache with no FPU.  
There are also 33mhz and 40mhz versions, ranging in price from around 
$600 (33mhz, no FPU) to $1500 (50mhz with FPU).  A 33mhz 68040 version 
is coming out in the next few months, and a 40mhz 68040 version is in 
the works (as soon as Motorola starts shipping the chips).  The 
PowerCache's are   available in a universal version, which fits every 
mac from a  Classic to a IIci with the appropriate $39 adaptor, and 
there's  also an SE/30-specific version which doesn't take up the PDS slot
(the universal version with the SE/30 adaptor uses the PDS slot).
All the PowerCache's have 32K of RAM cache built-in (which you can
enable/disable with a control panel)

In general, you can trade one PowerCache or adaptor at any time for
another one of equal or greater value.  All you pay is the
difference in price.  For example, you can trade one adaptor for  
another for free (since there's no difference in price), or you
could trade the SE/30-specific PowerCache for a universal
PowerCache (or vice versa) for free.  You could also trade a 33mhz
PowerCache for a 50mhz PowerCache, or a 50mhz 68030 PowerCache for
a 33mhz 68040 PowerCache, for whatever the difference in price is.
As a matter-of-fact, there is an even better deal in this last 
case.  If you buy a 50mhz PowerCache before November 1, you can
upgrade to the 33mhz 68040 PowerCache for $300 less than the normal
upgrade price (which works out to $99 if you upgrade from the 50mhz
with FPU, and $399 if you upgrade from the 50mhz without FPU).


Hope this helps,

--
Steve Kanefsky
Newsgroups: comp.sys.mac.games