Thanks for the reply!
BigEd wrote:
Welcome! Yes, the various microphotographs of original 6502 die will tell you something about the process size.
Previous calculations suggest 5 micron for the 6502 captured for the visual6502 project.
Segher has said:
Quote:
Quote:
There's a good image of the die still in the package on slide 20 of 65
http://visual6502.org/docs/6502_in_action_14_web.pdfFrom that, i get a north-south dimension of 3.5mm; and that leads
to a minimum gate length of 4.75um, so maybe it is 5um? I thought
it was supposed to be 8um. I get metal track pitch of 17.5um fwiw.
and Peter Monta replied:
Quote:
Yes, I get pretty much the same numbers: overall chip size of 3.7 by 3.3 mm
(12 square millimeters) and about 5 micron transistors.
(The track pitch of 17.5u might well imply a metal width of 8u, which someone might have taken to be the process node. But the transistor gate length, usually as the as-drawn width of polysilicon, was the usual measure in my day.)
Oh, that's interesting! So the issue here is that the version of the 6502 used on visual6502.org is revision D. (see slide 24 as well as
http://www.visual6502.org/images/6502/index.html)
The original 1975 chip (rev A? not sure) was 168 x 183 mils (=4.27mm x 4.65 mm), according to
EDN's article in September 1975, which mentioned that it "will be shrunk 10% to 153x168 mils soon". (=3.89mm x 4.27mm)
I can't remember exactly where I read it, but I seem to remember that the 10% shrink was an engineering design improvement rather than a process change. (I will edit this comment if I find the source again)
At any rate, I wouldn't be surprised if the rev D used in visual6502.org was 5um.
Just to crunch some ratios assuming a pure die shrink without any redesign: (4.27 mm x 3.89 mm of the 10% die shrink mentioned in EDN)/(3.7mm x 3.3mm mentioned in your quoted excerpt) = something in the 1.15 - 1.18 range, which would more likely imply that the original 6502 was around 6um rather than 8um. But that's just me with a quick off-the-cuff extrapolation.
I really wish the people who take the time to create these amazing die shots would include a reference gauge in their photos
![Sad :-(](./images/smilies/icon_sad.gif)
so it is possible to determine the die size. (and document which date code they used)
Pauli Rautakorpi aka birdman86 has a ton of die shots on Wikipedia (does anyone have his contact information?) including a
Rev A 6502 but what are the exact die dimensions? ¯\_(ツ)_/¯