Conference hydra::amiga_v1

dir a dir/tit=cpu and check out the note on cpu accelerators.

I started a thread and there was a fairly long reply regarding
the products you are interested in.

Mike

    Hi,
    
    I've already read the related notes.
    
    From what I've seen, I've deduced the following:
    
    .	The A2620 and A2630 are official boards. Very fast in their class
        they are also the expensive options. It fits in the CPU slot.
    
    .	The Mega Midget Racer is a "piggy back" board with 68000 fallback.
        Originally '020 based it is now '030 based. Good compatibility.
        Moderately expensive.
    
    .	The A5000 had initial teething problems. It is the cheapest entry
        level board in the UK. Based on a 16MHz '020, it is compatible with
        the production sw. It also suports 68000 fallback.
    
    . 	The B5000. A 25MHz '030 board. No info.....
    
    
    I primarily want an accelerator for DTP and Ray Tracing. I was advised
    that given a choice between 32 bit memory and a FPU I should get the
    memory. Is this correct? 
    
    Are the above deductions correct. (Sorry about the duplication of info,
    but as a student, I'm kissing my grant goodbye with this! - I don't
    want to make any mistokes :-))
    
    Dave
     

For most things, you do indeed want 32 bit memory more than you want
an FPU. However, for anything that's FP intensive (i.e. - ray tracing),
an FPU sans 32-bit memory is more cost effective than a system with
32-bit memory sans FPU (haven't checked in a while; price changes may
have changed that).

Unless you don't feel the DTP needs accellerating, this won't change things.
The DTP software shouldn't need the FPU at all, so a board with no 32-bit
memory will be pretty much wasted on it. On the other hand, an FPU-less
board that gets your ray tracer in 32-bit memory should show a noticable
performance gain. So buy a board with enough 32-bit memory to support your
applications, and a socket for a 6888[12].

	<mike

Re .3:

I have to disagree slightly with the use/nonuse of an FPU by DTP software.

Graphics software usually (though not always) makes free use of floating-point
arithmetic. It is possible to optimize for non-FPU processors by sticking with
integer arithmetic from "wherever practical" to "virtually always," depending
on how strongly this goal is pursued by the programmer. I'd hesitate, however,
to make the blanket prediction that all DTP software sticks to integer
arithmetic for transformation operations- I'd guess, FWIW, that the reverse is
more often true.

If you have the option, of course, try out your *specific* DTP package with and
without an FPU and compare the results.

Cheers,
	Bob

re .4

I said "shouldn't." I did consider that some DTP operations use FP, but
I don't think it's important. There are things that pretty much require it,
but I suspect that those are relatively uncommon operations. This is
compared to ray-tracing, which is pretty much all FP. How many DTP packages
have versions of the program available with the 88[12] wired in?

All FPU is about the only case where having an FPU without 32-bit memory is
a real win; an accellerator without a CPU running async run anywhere from 90
to 130% the speed of an unaccellerated Amiga (again, these figures are
based on old hardware; newer hardware may do better), and up to about
150% with well-designed sync. With the extra memory, those same boards get
from 300 to 1000% the speed of a stock system.

The advice about trying *your* DTP package is excellent though. That way,
you can try the things you do, which may be heavy on what I consider
"uncommon".

	<mike

    Hi,
    
    Well, I phoned SSL yesterday and had a lengthy talk with them. They
    seem nice people, admitted that there were problems with the products
    and described roughly what the problems were.
    
    As a guide I've included some info on their products. All prices are in
    sterling.....
    
    
    				A5000		B5000		B5000-40
    --------------------------------------------------------------------
    Processor			'020		'030		'030
    Clock Speed			16MHz		25MHz		????
    
    FPU Support			Optional	Optional   	????
    
    32 bit memory (supplied)	1 Mb		1 Mb 		4 Mb
    Memory speed		80 ns		70 ns		70 ns
    Expandable to...		4 Mb		4 Mb		32 Mb
    Memory price:  /Mb 		65		69		69
    		   /2 Mb	63 (?)		65		65
    
    Solder method		Hand		Hand		Machine
    Fit Method			------------- Piggy Back ------------
    Price			295		595		1149
    
    
    
    The choice of FPU is either a 68881 or 68882. The 68881 comes in 20MHz
    or 25MHz; the 68882 in 20, 25 and 33MHz
    
    The reason for hand soldering the smaller boards is that they have a
    50/50 split between soldering and construction. The B5000-40 has a
    80/20 split. 
    
    
    I think I'll plump for the A5000 with 2 Mb of memory......
    
    One question. If I were to run PageStream on this and 2 Mb of 32 bit
    memory was enough, would it run on a combination of 32 and 16 bit
    memory?
    
    
    Cheers dave...
    
    As it's my last day, I'ld just like to say thanks to everyone who has
    asked questions and answered mine. It's amazing just how much you learn
    when enjoying yourself......  See you in 8 months!!!!