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potatohead

Dual 6502 chip?

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Sometime around '84, I ended up with some data books. 6502, 6809, 6800.

 

Still have the 6809 one, but have lost the others. These were entire catalogs, coupla three hundred pages or so.

 

The one with the 6502 in it had lots of different chips in there. One in particular kind of stuck with me, and I wonder whether or not it was ever produced.

 

So this 6502 was like ordinary 6502 chips, only there were two of them! They ran on alternating clock cycles! There were some extra interrupt and reset vectors and such too. I don't recall what was done with the stack, whether another page was used, or it was shared, or what.

 

A recent discussion about multi-core devices sparked this memory, and I'm just kind of curious today as to whether or not the documentation can still be found. The idea of two 6502 chips running interleaved like that is kind of interesting.

 

Did you see that part? Do you have the old data books from about that time?

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This sparked a interest to look around the net, so far i have ran into this old topic http://forum.6502.org/viewtopic.php?t=217

 

Didn't the Franklin ACE 1200 have twin/dual 6502s

 

or check here http://www.cpu-world.com/info/id/Rockwell-identification.html

 

are you sure it wasn't a Microcontroller based off the 6502

Edited by madmax2069

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Well, that thread identified the part!

 

I have a Rockwell databook from 1984 or so that has advance information on a part (6529?) with two '02 cores operating out of phase. That would have been a fun part. Anybody know if these saw the light of day?

 

That's the one! Thanks. Looks like it is a micro-controller.

Edited by potatohead

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Well, that thread identified the part!

 

I have a Rockwell databook from 1984 or so that has advance information on a part (6529?) with two '02 cores operating out of phase. That would have been a fun part. Anybody know if these saw the light of day?

 

That's the one! Thanks. Looks like it is a micro-controller.

 

No problem, i hate it when you remember something and it sticks in your head until you can recall it or find info about it. it can get rather annoying at times.

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You'd need different Stacks for sure.

 

It'd also need some sort of "Test and Set/Clear" instruction although the 65C02 does have TSB/TRB. Additionally you'd probably want the initiation of that instruction to temporarily halt the other processor.

That way you could serialize resources.

 

Some sort of signalling mechanism as well would be helpful, such as generating an IRQ for the other core.

And a means to start/stop the other core. In a powerup situation you'd only really want one core going until the OS could do some initialisation.

 

Although you could get around the signalling issue using a flag that'd have to be polled periodically. Similar with the start/stop thing, seperate vector sets and flags could handle that.

 

In the case you couldn't be bothered with a full-blown OS that handles multiprocessing, the second core could just be used as a workhorse - e.g. doing FP chores and looking after the Interrupt handling.

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Didn't the Franklin ACE 1200 have twin/dual 6502s

It had two processors a built in Z-80 to support CP/M, along with the 6502, but not dual 6502s.

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