Faster/wider CPU...

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Dave
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Faster/wider CPU...

Postby Dave » Sat Jan 21, 2012 4:29 pm

I know that Gold Cards, etc use much trickery to make a 68020or 68040 forget who they are and pretend to be a 68000.However, there are faster 68000 and 68008 processors that should easily interface with the existing design without the great trickery of the Gold Card designs...

Does anyone have any thoughts or knowledge on this?


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Re: Faster/wider CPU...

Postby Dave » Sat Jan 21, 2012 5:20 pm

To clarify, I'm looking at the 68EC000. I like the idea of a 16MB QL, and there's a faster 10 MHz part as well as the 8 MHz part. Can of worms, I know, I know... :)


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Re: Faster/wider CPU...

Postby Zerover » Sun Jan 22, 2012 12:53 pm

I think the one you want is the MC68HC001, which is 8-bit compatible. It can address 16MiB and runs up to 16MHz.


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Re: Faster/wider CPU...

Postby Dave » Sun Jan 22, 2012 6:04 pm

The EC and HC variants both do that. I can, however, obtain EC variants for less than half the cost of a similarly clocked HC.

I'm curious if there's a simple way to have a faster CPU than the 7.5MHz of the 68008, and/or if there's a simple way to have wider memory accesses, and still use the onboard facilities, like the gold cards do, but without lots of heavyweight custom logic.

I am looking at whatever comes out of this thread being an open-source design.


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Re: Faster/wider CPU...

Postby Dave » Tue Jan 24, 2012 10:03 pm

A few people (okay, two!) have asked me what I'm doing...

I have a 68EC000 chip accessing 2MB of RAM, booting JS ROMS and producing the corrupted output of an otherwise successful boot. I'm working on resolving the video issue, and getting the keyboard side up (hello 8049 and friends!)... but I have no plans to get microdrives, serial or joystick ports working at this time. I do want it to take standard expansions so I can use a floppy disk interface, etc.

It's just personal exploring at this stage, but if anything comes of it, I'll share.

Photos to come.


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Re: Faster/wider CPU...

Postby Brane2 » Wed Jan 25, 2012 12:53 pm

68K chips are outrageously expensive, even simple ones, like 68/S/EC000 etc and higher model prices ( 68030/40/60) are totally crazy.

It seems as a much more worthwile path to go for a good modern-but-cheap FPGA ( like Xilinx Artix or Spartan-6) and synthesize it there.


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Re: Faster/wider CPU...

Postby Dave » Thu Jan 26, 2012 5:29 am

I can get 68EC000FN16 for $4 each.


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Re: Faster/wider CPU...

Postby twellys » Thu Jan 26, 2012 1:50 pm

Now I'm a contractor, I'm starting a FPGA that interfaces to a 68020...

... and yes, their service life is 30 years.

Now, how old is the QL? ;)


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Re: Faster/wider CPU...

Postby Dave » Thu Jan 26, 2012 5:12 pm

Here's my thing: I want to "do something" and I don't know how to work with FPGAs. I'll sit here and play with what I 'sort of' know. It is only playing, after all...

If I could team up with people (even given my limited skills) and contribute towards some kind of new machine, I'd be ecstatic, but it doesn't seem very likely to happen...

I'm very open-minded.


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Re: Faster/wider CPU...

Postby Brane2 » Thu Jan 26, 2012 6:10 pm

Mother nature created playing as a learning tool.

So, while you are playing, you can use that to learn something new.

Xilinx has good chips and totally useable tools.

Why not ?

It's just a suggestion.

WRT to that 68EC000 for $4, I can get PIC16F1527 with shitload of periphery and 28K of FLASH onboard for about half that money. In the terms of logic on chip PIC wins hands down.
Heck, cheap Microchips MIPS-based 32-bit models are not much more expensive. And they come with boatloads of stuff onboard. And mountain of FLASH.

I don't see any other good alternative that could even come close to pay back for invested time. FPGA has no alternatives. And it's not that expensive. Smallest Spartan6 chips are less than €20 and for €60 you can get very decent one and use it for more than just a very decent 68K-like CPU...

EDIT: And BTW you can get cheap development board that already contains most of what you need, so it's unlikely that you'd have to solder as much as program... ;o)


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