From: kanefsky@halcyon.com (Steve Kanefsky)
Subject: Re: Daystar and SE/30
Organization: The 23:00 News and Mail Service
Date: Tue, 13 Oct 1992 19:39:18 GMT

In article <1992Oct13.163046.18478@worldbank.org> Masud Cader <mcader@worldbank.org> writes:
>Could someone please tell me about their experience with the SE/30 Dystar
>card.  If I buy into it, I would use the extra slot for (Passthru slot)
>for a Radius color pivot monitor.  

DayStar doesn't make an SE/30 PowerCache with a pass-through connector.
They make a universal PowerCache which, with an adaptor, you can
use in an SE/30.  It does not, however, have a pass-through connector.
They also make an SE/30-specific PowerCache which bypasses the PDS and
plugs into the CPU socket.  Since very few SE/30's have CPU sockets
(but they do exist), you will most likely have to send your motherboard
in to DayStar to have one installed.  You can then use your PDS for
whatever you like, including a monitor card.  The SE/30-specific
PowerCaches are just beginning to ship, so I doubt you'll find anyone
with first-hand experience yet.

>I am especially interested in specifications, speed experiences, and
>compatibility.  I read the reports at sumex already, and they do not let
>me know enough about the final shipping Daystar card.  

Just about everything you read about the universal PowerCaches should
hold true for the SE/30-specific version.  In general they are very
fast and truly 100% compatable.

>Example, if I disable the init does my Mac SE/30 revert to its factory
>processor?  If I do not buy a math co-processor, will my software which
>requires a co-processor still work at the higher CPU clock speed, or do I
>have to disable the card?  In light of the IIci price drop does it still
>make sense to upgrade with a Daystar (How is the 33 MHz upgrade...similar
>to a Performa 600? Is the 40 MHz similar to the IIfx, and finally is the
>50MHz similar to a Quadra 700?). Note:  Similarity is defined in terms of
>performance. Comments are requested.


Once the PowerCache is installed, it cannot be disabled short of
physically removing it.  The init (actually it's a control panel) simply 
turns the 32K external cache on and off just in case you find a program 
which isn't compatable with the cache (I haven't found one yet, including 
many new and old shareware and commercial games).

If you don't have an FPU installed on your PowerCache, but you do have
one on your motherboard, the PowerCache can use it.  The CPU on the
PowerCache doesn't have to slow down to the speed of the FPU, but there 
is some clock synchronization that needs to take place.  There's a slight
speed penalty but nothing compared to the benefit you get from the FPU
for certain operations (not many programs take advantage of the FPU, but
when they do the FPU speeds things up considerably.  As a comparison, my
50mhz PowerCache running Software FPU ran 30 times slower in an FPU-intensive
benchmark than a 16mhz hardware FPU).  DayStar even includes software
which speeds up some applications that don't make explicit FPU calls (it
reroutes some SANE calls to the FPU while maintaining all the accuracy
of SANE).  

In general, a Mac equipped with a PowerCache is as fast or faster as a
Mac which was designed with an equivalent CPU.  FPU's and built-in video
and 16- vs 32-bit data paths make the situation a little more complex,
but not as much as you'd think. Thus a Mac with a 33mhz PowerCache is faster 
than a IIci, and should be faster than a Performa 600 (because of the cache).
A Mac with a 40 or 50mhz PowerCache is at or beyond the level of a IIfx.
None of the PowerCaches quite reach Quadra levels (until the '040
PowerCache comes out later this year).  The 50mhz is in the ballpark in
CPU speed, but no 68030/68882 combination can match the 68040 for
floating-point operations.  Quadras also have fast SCSI and built-in
video, although you'll be amazed at how much a PowerCache will speed up
your built-in video (actually the Quadras don't have accelerated video
at all -- it's mostly the fast CPU and dedicated VRAM that makes the video 
so fast.  Add a PowerCache to an LC or LCII and now you've got a fast
CPU and dedicated VRAM).

--
Steve Kanefsky