Need explanation of the CPU and FPU technology on turbo boards

[kidkoala]

i'm not telling you to stop posting, i'm telling you to post things that benefit the thread more, and not things that already are said, that's all. please don't feel affended, it's just positive criticism..

ofcourse i can't make you stop posting other stuff, but then everybody else has to scroll like mad to get to the interesting parts

[AmiDude]

@kidkoala wrote:

ofcourse i can't make you stop posting other stuff, but then everybody else has to scroll like mad to get to the interesting parts

Then don't respond to my posts anymore...It's because of
you that people has to scroll like mad...It's got nothing
to do with FPU's anymore.

[kidkoala]

please, let the next post be an informative topic-related one and i'll scroll right down to it and maybe respond as well!

[AmiDude]

OK, I've got various FPU's on my Amiga's,
(25Mhz, 40Mhz and 50Mhz) and they don't do
any s**t! How do you like that...
:lol:

[kidkoala]

hehe i guess that sums you up..

[AmiDude]

@kidkoala

Don't be so offensive dude...If you got nothing
interesting to say, then get the f**k outahere.

[Hammer]

Too many to mention. GPU's are not usually measured in FLOPS (FLoating point Operations Per Second) but in pixels/texels per clock, or more commonly now in the number of pipelines and shaders.

Just google AMD "Stream Processor" and GFlops.

For fragment/shader programs, AMD "Stream Processor" (Radeon R580 core) has peak performance of 375 GFlops.

[derringer3]

@amidude

About a few month ago I played Oblivion game on pc, its got about 25-30fps avarage on the highest settings. Then I accelerate a little more my pc (ddr2 800MHz/Core2 CPU etc.)
I didn't notice the difference in most way, but fraps program show: now its about 35-40 fps.)

In amiga I try many fpu, with differend oscillators. I learnt that some programs wich use "3d" effect often speed up. (Try ambermoon, I tried with an 68000, 68010, 68030 with different MHz FPU-s. 20MHZ-24MHz-27MHz-32MHz Now its clocked at 40MHz, but my 68030 still 14MHz. You will see the difference.

That's true, that running assyncronously from the CPU, you got to checked, it's worth the effort. I think its depends mainly, which turbo board you use.

Anyway If You don't use any 3d game, or 3d rendering, sound converting application, you will not notice the difference, because its only 1-2%

[kidkoala]

@derringer3

great, one who has thoroughly tested this and has proof of performance, hehe what kind of miggy and turbo board are those chips mounted on? cause my previous opinion is that when you have a big difference from the cpu to the fpu, the fpu needs to wait for the cpu to feed it all the time, you seem to have the opposite experience..
i'm going to try the same thing with my sx32@40mhz and fpu@33 w/oscillator@33mhz, here the cpu is faster in hertz, but if the fpu can finish it's job in less cycles cause it has more calculation-power, it will speed up the process (given there's something 3d-related calculations to do ofcourse).

@hammer

is it the same (or similar) with the gpu's now, and memory, as it is with the linear increase of cpu-performance; doubled every 2. year or something? i've always been fascinated with that, but i guess it's about to change because the new architecture with low-power, multi-core etc. breaks the linear curve?

[Karlos]

@Thread

Well at least there are no PPC powered amigas that don't have FPUs in them so at least you know your PPC applications probably make use of it if they do any floating point at all ;-)

That said, not that many have a SIMD vector unit.... ;-)

[derringer3]

@kidkoala

I've got an a500 with m-tec 68030/68882 board
By "factory" default it contains a 68030/16Mhz which is clocked at 14,2MHz and a 68882/16MHz which have got a separet oscillator. This is clocked at 20MHz
So about the performance:
 
68882 at 20Mhz: 0.48Mflops
68882 at 24Mhz: 0.51Mflops
68882 at 27Mhz: 0.58Mflops
68882 at 32Mhz: 0.68Mflops
68882 at 40Mhz: 0.79Mflops

You should look at, that sometime you got smaller advantage, when the estimated performance at higher MHz is indicated that. So there is no linear advantage compared to MHz. The best output of course is that the two proccessor  working syncronously. (For example in my system 42MHz would be more effective than 40MHz, and maybe 43-44-45MHz. But a 50MHz 68882 will be faster than an optimalised syncronouly 42MHz.

Anyway a guy told that, in an other forum post, that his A1200 with Blizzard 1230-IV got an 50MHz FPU, and its got 1,33 MFlops.
If I'am able to overclock my 68882 to 50Mhz, I don't think its got 1,33 Mflops, probably 0,9Mflops.

Of course the bandwith of A500 bus and A1200 bus different a little bit.

[Hyperspeed]

stop aRgUiNg!


:laughing:

[DonnyEMU]

Please I was an Amiga developer, I am not an average user. My point is simply this, even with a 16 mhz upgrade and an FPU and a Crystal on an A500 the upgrade is hardly worth any noticeable increase, especially with a motherboard that internally runs on a rate that is compatible with NTSC/PAL clock rates.

The point simply that I was making is most people buy an FPU to see a speed increase.. I had the special IEEE libraries and into the 90s I kept that machine and tried software that supported them as well too..

The point I am making is it's more worthwhile to get an accelerator that combines the FPU and CPU with memory. That's where you'll get your speed increase and programs that really take advantage of the special math operations..

Many later Amiga's didn't come with FPUs like the 030 machines and above which had the EC030 chips. Some had them built right into the cpu.

The response I was talking about was specifically the people with FPU accelerators on the 68000 chips. I probably have an old A/C guide from like 91 which lists programs that support FPUs and my point is you have to differentiate programs that just support using the mathieee libraries and those that are code compiled for an 20/881 030/882 etc. from the others because they work differently and support the CPU differently. Some programs for a while didn't run when the EC030 chips showed up..

A nice database and list out on the internet would be cool if someone would make it..

[Hammer]

is it the same (or similar) with the gpu's now, and memory, as it is with the linear increase of cpu-performance; doubled every 2. year or something? i've always been fascinated with that, but i guess it's about to change because the new architecture with low-power, multi-core etc. breaks the linear curve?

Moore's Law refers to transistor count. Refer to http://en.wikipedia.org/wiki/Moore's_law

[Vulture]

@Piru

of the apps I listed, the only one that requires an fpu to run is actually Lightwave 5.

[shoggoth]

rkauer wrote:
Just a memo: you could NOT use a faster FPU than your CPU. If you bought a faster FPU, simply put a cristal the same clock of CPU.

kidkoala wrote:
I think it's like this: if you have a cpu@30mhz and a fpu@50mhz, then the fpu would have to wait for the cpu all the time, because it's so much faster.
it's better if they have about the same Mhz to cooperate better, meaning there's no point in having a really fast fpu if the cpu is lagging behind.

Dudes, no offence, but you have it all wrong. The FPU is faster at floating point calculations (naturally), but it still uses a lot of cycles to perform it's calculations. The CPU waits for the FPU, not the other way around. Speed up the FPU, and the CPU spends less time waiting.

This has been tested and verified on other architectures.

-- Peter