6502.org

Can anyone find a schematic of the NMOS 6502 core?

I don't know if you'd ever find such a thing, but there are various VHDL and Verilog listings of it. I'm not prepared to give you a URL, but it shouldn't take long to find. I know there are links to some on this forum.

Well then one thing's for sure: if I take a NMOS 6502 and open up the plastic DIP, I should find the silicon in one. Just how can I open up the casing, anyway?

Don't count on it being useful for reverse engineering and it definately won't work after you do this, but if you just want to take a peek at the die, you should be able to slice at the package with a dremel. The diamond bit will definately work and the carbide or the reinforced cutting disk may work.... depending on if the package is ceramic or plastic. Keep the area you are cutting wet, either with a spray bottle of water or just by working in a dish of water (but keep your dremel very dry) and wear safety glasses and a dust-filtering mask.

It would be a lot faster to learn one of the HDLs and get an already-written 6502 model and figure it out than to draw a schematic of something like 3500 gates and 10,000 transistors. But at least the older NMOS chips have feature sizes that should be big enough to see with a powerful, high-quality optical microscope. That's not the case with the newest chips.

Here's a 6502 that was built with standard logic parts.
http://home.hccnet.nl/g.baltissen/pod6502.htm

But it seems that the link to the schematic doesn't work.

If you would like to see a picture of the die, try this link :

http://micro.magnet.fsu.edu/chipshots/mos/index.html

-Wally

What about
http://www.baltissen.org/htm/ttl6502.htm

I renewed everything and placed a detour in every old page I knew. Must have slipped through the proces.

The pictures of dies for most chips clearly show regular features. E.g., looking at most 8-bit processors, you'll see somewhere in the ALU section eight columns of nearly identical circuitry. What amazes me is that the 6502 shows no such regular structure, implying every transistor was placed and/or optimized by hand. I *so* don't want to be the person responsible for doing that!!

IIRC, it was laid out by hand on somebody's kitchen table. Or maybe that was the WDC version......

I think that was the 816, but may also have applied to the C02. It
seems to me that Mr.Mensch reveals this in an interview or two which
you could probably find elsewhere on the net. ( Maybe Jim Brain's
Interview ? )

-Wally

Yeah, I think I remember that the earlier ones were laid out by hand (to use up die space most efficently) and that the 816 was an abnormal design because it was still being laid out by hand in the age of computer-assisted layouts.

Yeah, sounds like the custom chips used in the Amiga. I wonder if one of the reasons the Terbium will be so "revolutionary" is because it will be a computer-synthesized chip.

Do we know anything about the Terbium yet ? Such as basic arch. ,
backward compatibility, on board resources etc ? Production date ?
Is anyone here a member of the mailing list ?

-Wally