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68000 Chip?

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Hey guys,

 

This just occured to me. As I understand it, the Jaguar uses a 68000 chip as it's "control" processor, and also handles stuff like I/O and whatnot. As I understand it, also... a lot of games, (ports in particular) use this processor almost exclusively and take almost no advantage whatsoever of the Tom & Jerry processors (please correct me if I'm wrong).

 

Now, I know that this is a very basic processor that Motorola has made that many computers have come with (including Apples and some early Macs, right?). I know that with Intel Processors, they usually make different speeds of chips.

 

Is it possible to swap out the 68000 chip with say a 68020 or 68010 (??) and would some of the games go slightly faster... like for example Fight for Life?

 

Has anyone tried this?

 

 

Thanks!

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Switching the 68000 for a more powerfull/faster version I doubt that it would make any difference for these reasons...

 

a) Even assuming that the necessary pins are compatible with the current PCB layout unless you create a new PCB you wont have any extra address/data lines available so it can process any more information per clock period

 

b) As the processing speed is limited by the clock so you would have to increase the clock speed, probably by increasing the speed of the master clock which in turn may case timing issues with some accesories and software.

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You could increase the speed of the Mc68000 or replace it with a faster processor, however i doubt it will enhance 3d graphical abilities. For a start fight for life definetely does not use the Mc68000 for its core mathematical number crunching. If a standard Mc68000 could throw around that many polygons, then we'd all be using them.

 

Your best bet at upgrading the jaguar, would be to add some Level 2 cache and overclock Tom and Jerry! Good luck.

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Hi!

 

Hey guys,

 

    This just occured to me. As I understand it, the Jaguar uses a 68000 chip as it's "control" processor, and also handles stuff like I/O and whatnot. As I understand it, also... a lot of games, (ports in particular) use this processor almost exclusively and take almost no advantage whatsoever of the Tom & Jerry processors (please correct me if I'm wrong).

 

Now, I know that this is a very basic processor that Motorola has made that many computers have come with (including Apples and some early Macs, right?). I know that with Intel Processors, they usually make different speeds of chips.

 

Is it possible to swap out the 68000 chip with say a 68020 or 68010 (??)  and would some of the games go slightly faster... like for example Fight for Life?

 

Has anyone tried this?

 

 

Thanks!

912059[/snapback]

 

You are wrong, that ports do just use the 68k.

First of all, you need to understand that any full game needs the following processors. There is no way around it:

-68000

-OP (graphics display)

-DSP (sound)

 

Optional would be GPU or Blitter. But I can tell you, that there probably is not a single official jag game out there that doesn't use those as well.

 

So the question is not if they are used or not, but how well they are used.

Besides, most ports work just fine. Almost all (if not all) of them were 2D titles anyway and run just fine on the Jag.

 

Also you can't exchange the 68k without doing a new main board design and even that would be useless, because no software would probably run on it unless it's custom written.

 

Regards, Lars.

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When you read official doc, the Jag has been designed for some differents processors, example, one bit indicate if it's a 32bit processor or not, some registers allows you to select big endian or little endian (for use with intel processor (Bad idea !)).

 

Perhaps you can put a 68020 without any modification but unsoldering and soldering the processor can be dangerous (Cms !) and you will be the only one with this proc !!

 

SCPCD has said that overcloking will be hard coz some problems will appear.

 

GT Turbo (Jagware) ;)

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When you read official doc, the Jag has been designed for some differents processors, example, one bit indicate if it's a 32bit processor or not, some registers allows you to select big endian or little endian (for use with intel processor (Bad idea !)).

 

Perhaps you can put a 68020 without any modification but unsoldering and soldering the processor can be dangerous (Cms !) and you will be the only one with this proc !!

 

SCPCD has said that overcloking will be hard coz some problems will appear.

 

GT Turbo (Jagware)  ;)

912993[/snapback]

 

 

Would there be any risk of damaging the cartridges if I did such a swap?

 

I mean, assuming that it did or did not work, when I first power it up with a cartridge in, is there a potential to damage it?

 

 

I'm not so concerned for the Jaguar, although I wouldn't want to needlessly ruin a system, I think it would be an interesting thing to try, if someone had a really beat up jaguar maybe....

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When you read official doc, the Jag has been designed for some differents processors, example, one bit indicate if it's a 32bit processor or not, some registers allows you to select big endian or little endian (for use with intel processor (Bad idea !)).

GT Turbo (Jagware)  ;)

912993[/snapback]

No no no, read the docs again.

 

The Jaguar chipset was designed to be able to work with other co-processors, so you could, for example, have an intel workstation with Tom running its graphics and Jerry running its sound. The Jaguar console was quite specifically designed to have a 68000 in it.

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Hi !

 

Tyrant is right.

 

One thing that is often confusing people is, in the development console they talk about the "Jaguar" architecture. i.e. Tom, Jerry and the "co-processor" (68k in this case) But not exactly "Jaguar" the finished game console...

So some things they talk about don't always apply to the finished system.

 

This is also what many confuse when they talk about the CoJag systems...

They are not modified Jaguars.

They are new systems based on the Jaguar architecture, with completely new board design and a lot of other differences, such as a better 68k replacement, harddisc, more ram and so on...

What many also don't know is, that the TOM and JERRY units on those boards are slightly different...

I once helped somebody finding a replacement of those for his CoJag board and in the end we found out, that he couldn't use the normal ones of a Jag board.

I don't remember exactly if the CoJag ones read version 1.2 or even 1.3...

in Jags I have only seen 1.0 and I think 1.1 in some models...

Then again we will probably never know if anything was actually improved or fixed or if it was for example just a version that is cheaper to manufacture with slightly different pinout or so...

 

About potential damage to carts, I don't think you need to be afraid.

The only damage I could imagine would be caused for example by shorting contacts or feeding a wrong power level to them. As long as your modifications don't do anything like that, you should be on the safe side...

 

And in the worst case, you can still try it with Trevor McFur or Supercross 3D carts.

If you fry those, it's not like anybody would miss them ;)

 

Although I can't see much of an advantage to replace the 68k with a 68020.

I mean, think about it. Even if the pinout is the same and you could replace them, and the 68020 is fully backward compatible. It would still run at the same speed, due to the crystals inside the Jag. And replacing those would end up with messed up timing, video and audio signals. And if you don't write a custom program to use the 68020 commands, you will probably not see any improvement in speed.

 

Regards, Lars.

Edited by Starcat
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Interesting, I've long been curious about the CoJag boards, specifically, how they manage to get a second lightgun input, when Tom only has one gun input pin (documented, at least, I think the pin next to it is unused).

 

How did you work out that the chips are different? are they a different size/shape/package? more/less pins? Details man, details :).

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Anyone familiar with the 68000 knows that it takes a relatively high number of cycles to execute a single instruction. A 68020 or above would in fact run significantly faster, even with the same 16-bit data bus and the same clock speed, because of certain kinds of instructions taking fewer cycles (and also because of on-chip cache!)

 

Is the 68K in the Jaguar a 64-pin DIP? A 68010 (the speed increase is probably negligable) should work in there, but maybe even one of the many Amiga accelerators that plugged into the CPU socket...

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At least once a year someone comes up with this idea to overclock and speed up the Jaguar. It was actually tried and from what I've read the audio/video sync gets too screwed up, and both Tom and Jerry chips overheat. And you get all that for the measly speed boost from 26mhz to 33mhz!

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Hi Tyrant!

 

Interesting, I've long been curious about the CoJag boards, specifically, how they manage to get a second lightgun input, when Tom only has one gun input pin (documented, at least, I think the pin next to it is unused).

 

How did you work out that the chips are different? are they a different size/shape/package? more/less pins? Details man, details :).

915003[/snapback]

 

It was all done with e-mails, so I can just repeat what he told me.

He said that he tried replacing the processors and with the jaguar ones, even though he said they would "fit" (which I assume means, same pin count, same size etc) but they didn't run.

He then mentioned that the original ones on the board which were broken had a different version number printed on them. If I recall correctly he said something like version 1.2 or 1.3.

Acutually the Jag lightpen/lightgun abilities aren't working very well in the Jaguar itself. From what Matthias said in the past, I understood, that it works somehow, but not relieable enough for a game.

So maybe you are right and that was one of the changes. Or they added additional lightgun hardware to the boards...

 

About the 68020, you could be right that it has lower execution times.

I just figured, because the Jaguar 2 prototype used a 68020 too and it just supported compatibility mode to Jag at the same speed. That this would be the same if you just replaced the 68020 without changing the chrystals of the Jaguar.

 

Regards, Lars.

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Acutually the Jag lightpen/lightgun abilities aren't working very well in the Jaguar itself. From what Matthias said in the past, I understood, that it works somehow, but not relieable enough for a game.

915120[/snapback]

If you're refering to the horrizontal flickering nature of the input, its not really a big issue. All guns on all systems flicker like that, its just part of their nature, but with a little buffer and an averaging of recent positions you can get it stable enough to be accurate, so thats not really an issue, just a trade off between pin point accuracy and fast reflexes (the more accurate you want it, the more sluggish things become, due to the averaging of a number of recent positions).

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Hi!

 

I haven't played around with lightguns on the Jag myself, I just know what Matthias found out when he experimented with lightguns and I think the result was, that it only worked acceptable when there was a huge difference in contrast between the objects you wanted to hit. Or something like that.

 

Regards, Lars.

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Hi!

 

I haven't played around with lightguns on the Jag myself, I just know what Matthias found out when he experimented with lightguns and I think the result was, that it only worked acceptable when there was a huge difference in contrast between the objects you wanted to hit. Or something like that.

 

Regards, Lars.

916125[/snapback]

Difference in contrast? oh, you mean doing it that way? wow, thats low tech... but anyway this thread is getting very off topic now hehe. Suffice it to say that guns can be made to work just fine on the Jag.

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You can read in Atari docs that :

 

Jaguar has been designed to work with any 16 or 32 bit microprocessors with (up to) 24 address lines.

 

Software reference manual version 2.4 page 5

 

and the sheet after :

 

This allows the system to boot whether the microprocessor is a 680x0, an 80x86 or a transputer.

 

Page 6

 

So, using a 68020 is allowed.

 

 

GT Turbo (Jagware) ;)

Edited by GT Turbo

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Once again you fail to understand that they are talking about "Jaguar" (the chipset) and not "Jaguar" (the console). Read the docs more closely.

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Hi Lars,

OK, nearly 13 years later I want to add useful information thanks to Clint Thompson's collection and video!
Again, for the regulars here, no need for this information, but I think it is a common enquiry, unanswered.

They are new systems based on the Jaguar architecture, with completely new board design and a lot of other differences, such as a better 68k replacement, harddisc, more ram and so on...
What many also don't know is, that the TOM and JERRY units on those boards are slightly different...
I once helped somebody finding a replacement of those for his CoJag board and in the end we found out, that he couldn't use the normal ones of a Jag board.
I don't remember exactly if the CoJag ones read version 1.2 or even 1.3...
in Jags I have only seen 1.0 and I think 1.1 in some models...
Then again we will probably never know if anything was actually improved or fixed or if it was for example just a version that is cheaper to manufacture with slightly different pinout or so...

This is a nice video of one of several Cojag motherboards, and it clearly shows the version numbers. "Mmm Donuts!"



Of course, I did not go through all the Cojag motherboard photos, but based on Area51 board, no change, and at 26Mhz.

Cheers, JustClaws.
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It´s so funny .... I was thinking today. "Hmmm ... could a 68010 or 68020 make the Jag faster?" :D

Seems, I am only 13 years to late for the idea itself. :D

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The 68020 would be better... The internal cache would've been a wonderful addition especially keeping the 68K off of the bus even for but a short time. At least if someone does an fpga copy of the Jaguar hardware they could possibly use a 68020 or higher model chip.

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Hi Lars,

 

OK, nearly 13 years later I want to add useful information thanks to Clint Thompson's collection and video!

Again, for the regulars here, no need for this information, but I think it is a common enquiry, unanswered.

 

This is a nice video of one of several Cojag motherboards, and it clearly shows the version numbers. "Mmm Donuts!"

 

Of course, I did not go through all the Cojag motherboard photos, but based on Area51 board, no change, and at 26Mhz.

 

Cheers, JustClaws.

 

This adds a question... if Area 51 could essentially run on what was Jaguar architecture... could they then also run on an actual Atari Jaguar?

 

I realize you said the chips are slightly different... but I'm just curious if anyone has tried?

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I heard that the bus that the DSP sits on is full 32bit instead of 16bit like the game console...

Edited by philipj

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I wonder how much more the parts for the arcade board cost to manufacture over the regular Jag.

 

Forget the HD, just the 322bit DSP bus, 68010 and 4 meg RAM.

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