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Motorola 68881 & 68882 math co-processors...


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#1 Lynxpro OFFLINE  

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Posted Mon Jan 9, 2012 1:22 AM

I'm getting an itch to dig out my Falcon and upgrade it with a Motorola 68882 math co-processor after all of these years. Prior to my conversion to PC in 96 [which I later switched to Macs], I had my Falcon upgraded to 14MB of RAM but I never added the co-processor.

What's the consensus...is it worth it? Unless I'm mistaken, Cubase can use the co-processor, as can Mark Williams C and some DTP programs. But do any games [whether for STe or Falcon] actually use it?

I'm a little alarmed at some of the descriptions from some eBay sellers trying to sell these chips based upon their worth in gold. What a bunch of heathens. Just out of general principle, that makes me want to buy one to keep at least one of them out of a goldbug's hands. Maybe all of us with capable systems [whether Ataris, Amigas, and pre- OS X Macs] should do that...

But anyway... What other STs without upgrade boards can use such co-processors?

If I'm not mistaken, the MegaST has a slot for a 68881 [not sure if a 68882 will work even though it is the same pin configuration]. The same goes for a MegaSTe. [And the TT comes standard with a co-processor]. But what about the 520STe and the 1040STe? And if they do, can they also use a 68882 or simply a 68881?

I'm actually tempted to try to find an STe out there since they tend to be a bit more backwards compatible than the Falcon. I also retrieved my old 1040ST but it'll need a replacement keyboard and all the upgrades require additional boards.

As for the users on here that also use Amigas, can any of the Amigas [besides the 2000] simply pop in a 68882? I was reading up on the specs for the 600 and the 1200 but couldn't find any info on whether they have sockets or if an upgrade board is required...

Thanks in advance for any info...

#2 DarkLord OFFLINE  

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Posted Mon Jan 9, 2012 1:29 AM

The Mega STe, TT, and Falcon all have sockets for the FPUs. I don't think the Mega ST or 1040 STe does...not without some
kind of adaptor board.

I had a 1200 once - it didn't have a socket for a FPU either.

HTHs.

#3 Rybags OFFLINE  

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Posted Mon Jan 9, 2012 1:38 AM

None of the standard form ST/e has provision for it AFAIK.

I'd guess that there's probably accelerator or dedicated expansion boards out there with provision for it.

What benefit you'd get... that's the big question. In similar fashion that graphics functions use "A-line", maths uses "F-line" but it's up to the software in use whether to use those instructions or do the work itself with the native instructions available.

#4 moulinaie OFFLINE  

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Posted Wed Jan 11, 2012 6:07 AM

I don't think that any game will use the FPU. So you won't get any extra power with it.
Most compilers can use it (they detect its presence and use the correct maths routines with our without maths FPU).

If you are a programmer, that can be useful for you.
If you use some software with heavy maths computations (POV for example), this can help too.

For more infos, you can visit my page about the Kronos benchmark software, you'll find there a link to FPU tests:

http://gtello.pagesp...e.fr/kronos.htm

Guillaume.

#5 Ato OFFLINE  

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Posted Wed Jan 11, 2012 6:08 PM

Neither the ST models nor the plain STE models nor the Mega ST - caveat: not the Mega STE models! - would come with a plain socket for any of the MC68881/2. In order to provide hardware FPU support to hose models, they would have to be upgraded with the Atari FPU card. - Or whatever its name is. - Anyway, the Atari FPU upgrade card has one major disadvantage. It cannot be programmed directly, i.e. by using proper FPU mnemonics, but one has to program it by writing all the commands and data into memory mapped registers which obviously sucks big time due to the timing (ROM port!) and the usability constraints. But since an MC68882@32 MHz is available for just US$10 or max. US$15 on "YouKnowWhere", there is no reason to not get one. And the general assumption is correct, that most Atari software does not make use of it, since, at the time of the development of most of the software, those FPUs were just (expletive omitted) expensive and hence not available to the developers.

Hth. Cheers,
T.

#6 amiman99 OFFLINE  

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Posted Wed Jan 11, 2012 10:18 PM

On Amiga side (A1000, A500, A2000, A1200), the only way to upgrade to coprocessor is using accelerator cards. Most of accelerators or CPU cards have socket for one. The Amiga 3000 has 68882 built in and Amiga 4000 uses 68040 with coprocessor built in.
Most 3D rendering software would utilize one, as for games probably few.
My accelerator in A1200 has a space for 68882 50Mhz, but like you said, the Ebay prices are insane, I would love to get one.

#7 Lynxpro OFFLINE  

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Posted Wed Jan 11, 2012 10:29 PM

The Mega STe, TT, and Falcon all have sockets for the FPUs. I don't think the Mega ST or 1040 STe does...not without some
kind of adaptor board.
I had a 1200 once - it didn't have a socket for a FPU either.
HTHs.


That sucks. The STe line should've had it...then again...some might say they should've had a 68020 too! :)

What about the STacy, DarkLord?

And it is disappointing the A1200 doesn't have such a slot especially since it's a contemporary of the Falcon. I've been looking at boards for the A500 [since A500s go for cheap in MegWhitmanLand] but all the CPU upgrade boards so far haven't had FPU sockets.

Separately, it seems like Kickstart switcher boards in Amigaville are more common than TOS switchers ever were in Atariland. I can't remember anyone from my rather large Atari user's group having any TOS switchers back in the day. Then again, only a few people ever bothered upgrading to Rainbow TOS or TOS 2.6...they seemed far more amazed with NeoDesk which didn't really appeal to me back then...had it on the Falcon but GEM/TOS 4.0x was decent enough...


None of the standard form ST/e has provision for it AFAIK.


And I thought for sure the MegaST had a slot for the 68881 because I thought I'd remembered much talk about it and the ads for Mark Williams C certainly hyped how it supported it. Even some summaries I read on the net prior to creating this thread say the MegaST does have a slot.


I don't think that any game will use the FPU. So you won't get any extra power with it.
Most compilers can use it (they detect its presence and use the correct maths routines with our without maths FPU).
If you are a programmer, that can be useful for you.
If you use some software with heavy maths computations (POV for example), this can help too.
For more infos, you can visit my page about the Kronos benchmark software, you'll find there a link to FPU tests:



Nice web page.

I think I noticed that a multimedia player for the Falcon supports the 68882. I would've figured the MP3 portion would mainly use the Motorola DSP in the Falcon instead. Funny how a chip that was a contributing factor to the NeXT Cube's expense - a few years before the Falcon debuted - could now be implemented in Apple's cheap iPod Shuffles...


Neither the ST models nor the plain STE models nor the Mega ST - caveat: not the Mega STE models! - would come with a plain socket for any of the MC68881/2. In order to provide hardware FPU support to hose models, they would have to be upgraded with the Atari FPU card. - Or whatever its name is. - Anyway, the Atari FPU upgrade card has one major disadvantage. It cannot be programmed directly, i.e. by using proper FPU mnemonics, but one has to program it by writing all the commands and data into memory mapped registers which obviously sucks big time due to the timing (ROM port!) and the usability constraints. But since an MC68882@32 MHz is available for just US$10 or max. US$15 on "YouKnowWhere", there is no reason to not get one. And the general assumption is correct, that most Atari software does not make use of it, since, at the time of the development of most of the software, those FPUs were just (expletive omitted) expensive and hence not available to the developers.
Hth. Cheers,
T.



Did Atari actually market such a card themselves? In the US or Europe only? If they had, it would've been nice had they included a provision for the BLiTTER on it back in 87...

Such a shame those co-processors were so expensive back then [$300 plus if I recall correctly]. I guess a lot of publishers looked at it from the chicken-and-the-egg proposition. Gaming certainly could've been helped with them, then again, I don't recall PC gaming really taking advantage of FPU until the 386DX era...

I've seen a *new* 68882 for $15 at "YouKnowWhere" but I haven't seen any for $10. I'd definitely like a PM if you know of a place...

As I posted before, this is now a case of general principle too since I don't like the idea of gold hoarders buying up these uncommon FPUs for their gold value. They can do that to ultra-common Intel chips all they want to but don't touch these chips that Atarians, Amigans, and Classic Mac fans can actually use to this day...

One thing I did see on Amiga boards is some fascination with crystal oscillators. Not much explanation on them; I take it they may be used for overclocking...

Edited by Lynxpro, Wed Jan 11, 2012 10:34 PM.


#8 DarkLord OFFLINE  

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Posted Thu Jan 12, 2012 1:42 AM

Nope, the STacy doesn't have a FPU socket standard either.

#9 moulinaie OFFLINE  

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Posted Thu Jan 12, 2012 2:26 AM

Anyway, the Atari FPU upgrade card has one major disadvantage. It cannot be programmed directly, i.e. by using proper FPU mnemonics, but one has to program it by writing all the commands and data into memory mapped registers which obviously sucks big time due to the timing (ROM port!) and the usability constraints.

Hth. Cheers,
T.


Hello,

You're right about programmation, it's not so easy! I have written a FORTH interpreter/compiler and added recently the FPU support (because I found a 68882 for my MegaSTE). I have made a set of benchmarks that you can read on my page:

1) The paragraph "FPU Installation" shows the hardware part
2) A bit under, you'll find a paragraph about the FORTH benchmarks with and without the FPU. Even if there is a loss of time, the speed is really great!

http://gtello.pagesp...e.fr/mste_e.htm (english)
http://gtello.pagesp...e.fr/mste_f.htm (français)

Guillaume.

PS: don't read the paragraph "benchmark" that was an early test with Kronos and without the FPU. I couldn't change this as the FPU test in Kronos expects a 68030 and is not made for the couple 68000+68882.

Edited by moulinaie, Thu Jan 12, 2012 2:28 AM.


#10 Ato OFFLINE  

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Posted Thu Jan 12, 2012 2:34 PM

The name of the extension card is Atari SFP004. Installation manual: http://www.atarimani...o-processor.pdf and some pictures: http://www.maedicke....ware/sfp004.htm

And I have to apalogise because I was wrong. It was not a ROM-port card but one for the Mega-ST internal 68000 expansion bus. Sorry again for the wrong information.


You're right about programmation, it's not so easy! I have written a FORTH interpreter/compiler and added recently the FPU support (because I found a 68882 for my MegaSTE). I have made a set of benchmarks that you can read on my page:

1) The paragraph "FPU Installation" shows the hardware part
2) A bit under, you'll find a paragraph about the FORTH benchmarks with and without the FPU. Even if there is a loss of time, the speed is really great!


Whoopsy Daisy! Quite some improvement. Would be really nice if you could add support for the FPU-on-a-card for later comparison if we find somebody who has got one. :-)

Cheers,
T.

#11 Lynxpro OFFLINE  

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Posted Thu Jan 12, 2012 10:17 PM

The name of the extension card is Atari SFP004. Installation manual: http://www.atarimani...o-processor.pdf and some pictures: http://www.maedicke....ware/sfp004.htm
And I have to apalogise because I was wrong. It was not a ROM-port card but one for the Mega-ST internal 68000 expansion bus. Sorry again for the wrong information.



Impressive. I'm surprised it was 16Mhz; maybe Motorola didn't produce an 8Mhz version. Still, kinda a mismatch. Atari probably should've brought out a 16Mhz MegaST to match it in 1988 when this was apparently produced.

Considering how the MegaST was marketed for DTP, I'm surprised more DTP software didn't support the co-processor if this was available... [or did they?].

#12 guus.assmann OFFLINE  

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Posted Fri Jan 13, 2012 6:57 AM

IMHO there's not much use for a Co-Pro in DTP.
Please have a good look at what it does and also consider the cost.
For DTP, addition, substraction, multiplication and devision may be usefull calculations.
And single precision is enough (mostly)
Using a Co-Pro, dual precission is mandatory.
This means (relatively) big amounts of data to transfer, compared to single precision.
And a single precission calculation including the data transfer is faster when done by the processor itsself.

For trigoniometric calculations like Sine, Cosine etc the Co-Pro is much faster.

All of this should also read: Beware of benchmarks.
Do they really compare the correct and USED things for the application that I need.

Just my 2 cents.

BR/
Guus

P.S. I do have a SPF004 card and also a 68882 in my Mega-STE. I've clocked that one at 25Mhz....

Edited by guus.assmann, Fri Jan 13, 2012 7:00 AM.


#13 Lynxpro OFFLINE  

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Posted Fri Jan 13, 2012 7:57 AM

Neither the ST models nor the plain STE models nor the Mega ST - caveat: not the Mega STE models! - would come with a plain socket for any of the MC68881/2. In order to provide hardware FPU support to hose models, they would have to be upgraded with the Atari FPU card. - Or whatever its name is. - Anyway, the Atari FPU upgrade card has one major disadvantage. It cannot be programmed directly, i.e. by using proper FPU mnemonics, but one has to program it by writing all the commands and data into memory mapped registers which obviously sucks big time due to the timing (ROM port!) and the usability constraints. But since an MC68882@32 MHz is available for just US$10 or max. US$15 on "YouKnowWhere", there is no reason to not get one. And the general assumption is correct, that most Atari software does not make use of it, since, at the time of the development of most of the software, those FPUs were just (expletive omitted) expensive and hence not available to the developers.

Hth. Cheers,
T.



Ato, can you either post here or in PM where you've found $10 68882s @ 32Mhz? Thanks... The auction, ahem, that I'm "watching" ends in a couple of days and their price is $15...

#14 Shredder11 OFFLINE  

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Posted Sat Jan 14, 2012 8:23 AM

Some 3D CAD software uses it I believe and also quite a few demos do too. Other audio software like the Zero-X editor have a specific Falcon version that uses the FPU as well.

#15 Ato OFFLINE  

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Posted Sun Jan 15, 2012 7:32 AM

Ato, can you either post here or in PM where you've found $10 68882s @ 32Mhz? Thanks... The auction, ahem, that I'm "watching" ends in a couple of days and their price is $15...



Currently on "YouKnowWhereToBid":
140677848981
290656172263
220846013303 w. price suggestion
Simply look for "68882" and you'll always find cheap FPUs. Sometimes they are defect, sometimes they are only 16MHz. Sometimes you'll find 40MHz gems.

#16 Lynxpro OFFLINE  

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Posted Sun Jan 15, 2012 11:31 PM


Ato, can you either post here or in PM where you've found $10 68882s @ 32Mhz? Thanks... The auction, ahem, that I'm "watching" ends in a couple of days and their price is $15...



Currently on "YouKnowWhereToBid":
140677848981
290656172263
220846013303 w. price suggestion
Simply look for "68882" and you'll always find cheap FPUs. Sometimes they are defect, sometimes they are only 16MHz. Sometimes you'll find 40MHz gems.



Someone sniped me at the last second out of a brand new 32Mhz 68882 for $15.50. I should've set a max bid or just "bought now" for $18 with free shipping.

Thanks. I'll check those out!

#17 Lynxpro OFFLINE  

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Posted Sun Jan 29, 2012 9:16 PM

Just bought a "new" 32Mhz 68882 for $19. Now to get my Falcon out of storage. I'm assuming its just a plug-in process from the motherboard pic I just viewed off Google... It doesn't have a gold cover to it like some I've seen... [that might've been a 68881, actually].

#18 guus.assmann OFFLINE  

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Posted Mon Jan 30, 2012 3:53 AM

Hello Lynxpro,

For the Falcon, it is just a plugin and no other stuff needed.
And you can also isolate the clock input and have it running at a higher (or lower) speed than the CPU.
But there's one thing to know and your remark about gold makes me fear the worst.
These parts come in two different housings.
There's the PGA, with pins below the housing and the ceramic version may have a gold top.
This one will not fit in any original Atari computer.
For the Falcon you need the PLCC version, that has the pins along the four sides of the chip.

BR/
Guus

#19 Lynxpro OFFLINE  

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Posted Mon Jan 30, 2012 10:34 PM

Hello Lynxpro,

For the Falcon, it is just a plugin and no other stuff needed.
And you can also isolate the clock input and have it running at a higher (or lower) speed than the CPU.
But there's one thing to know and your remark about gold makes me fear the worst.
These parts come in two different housings.
There's the PGA, with pins below the housing and the ceramic version may have a gold top.
This one will not fit in any original Atari computer.
For the Falcon you need the PLCC version, that has the pins along the four sides of the chip.

BR/
Guus



Sonofa!

Thanks, Guus. I'll take a pic of it in the next couple of days.

Let me guess, Amiga add-on cards and old Macs could use the PGA versions...

The version I bought is listed as an MC68882FN33A...

Maybe I misread what you posted. I didn't get one with gold on it; looks like black plastic. From a Google Search, I found a link on an Amiga site describing the black version I got - with the same model number - as the PLCC version. Maybe I lucked out after all.

Edited by Lynxpro, Mon Jan 30, 2012 10:42 PM.


#20 guus.assmann OFFLINE  

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Posted Tue Jan 31, 2012 1:48 AM

Hello Lynxpro,

Yes, it sure looks like you scored.
Still it's better to be well aware of what to look for. (Sorry if I startled you)

The FPU and CPU don't need to be run at the same clock speed.
And on the Falcon it's not too difficult to increase the clock to the FPU. (And leave the rest as it is)
The 32Mhz will most likely run well at 40Mhz as well. And often 50Mhz or more is also possible.
So if you need even more speed, it's often very possible. (Justcut one trace , check if it's not going anywhere elas and add one oscillator block)
BR/
Guus

#21 DarkLord OFFLINE  

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Posted Tue Jan 31, 2012 3:23 AM

If I were gonna do that, I'd go ahead and do, or have done the other motherboard mods as well. Increase bus speed, DSP, etc, etc,...

I think mine is pretty well running at 40mhz across the system. It wouldn't take 50mhz though, became unstable. Oh well. :)

#22 Lynxpro OFFLINE  

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Posted Tue Jan 31, 2012 10:26 PM

Hello Lynxpro,

Yes, it sure looks like you scored.
Still it's better to be well aware of what to look for. (Sorry if I startled you)

The FPU and CPU don't need to be run at the same clock speed.
And on the Falcon it's not too difficult to increase the clock to the FPU. (And leave the rest as it is)
The 32Mhz will most likely run well at 40Mhz as well. And often 50Mhz or more is also possible.
So if you need even more speed, it's often very possible. (Justcut one trace , check if it's not going anywhere elas and add one oscillator block)
BR/
Guus



Thanks, Guus, for all your info.

If all of us with MegaST [assuming one has the 68881 co-processor add-on board installed], Mega STe, and Falcon owners took advantage of the dirt-cheap prices on these co-processors, maybe there'd be an incentive to enable FPU support in software amongst us retro enthusiasts.

I don't think I'm going to "overclock" this FPU by getting a different crystal. 32Mhz is probably good enough considering my Falcon is only a stock 16Mhz model. The only upgrade I have in it is the 14MB board that was installed circa 1994. I know one thing, I'm going to vacuum the interior before installing the 68882!

#23 guus.assmann OFFLINE  

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Posted Wed Feb 1, 2012 8:44 AM

Hello Lynxpro,

This is one of the things a forum is there for.
On the Falcon I would advise to buy a (very cheap at www.DX.com) converter from IDE to CF or SD.
And if you use FDDriver than two disks / cartridges is also possible.

The Mega STE may require one GAL to be replaced in order to get the FPU working. (I've had to do that on one -early- machine)
Technically, the 68882 will do but is not recognised by all programs. The 68881 is a bit slower with some things but is recognised by all applicable programs.

BR/
Guus

#24 DarkLord OFFLINE  

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Posted Wed Feb 1, 2012 12:53 PM

Just out of curiosity, what programs are known for working with the 68881 but not the 68882?

Thanks.

#25 guus.assmann OFFLINE  

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Posted Thu Feb 2, 2012 3:00 AM

@Darklord,

Please don't hang me if I'm wrong on this... ;)
There's a version of GFA Basic (Or is it assembler? I have it at home and I'm at work right now) that does support the 68881 and not the 68882.
Also some benchmarks do see the 68881 and not the 68882. But these do use the 68882 as the results are fast calculation results.
And if memory serves right, the Atari FPU card will only work with the 68881 due to the way it's accessed. Though I'm not 100% about this last one.

BR/
Guus




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