This is not directly 6502 related, and not really programmable logic. But it might interest a few people here, and this feels the right place for it.

TintTapeout https://tinytapeout.com/ is a relatively new service that drastically reduces the cost of producing ASICs. They coordinate your design sharing a chip with a bunch of others, spreading the cost. So instead of the tens of thousands it usually costs, you can get your own silicon for $300.

Don't expect to be able to build a drop-in 6502 replacement with it: you only get 24 I/O pins (8 input, 8 output, 8 bidirectional, all 3.3V), and the area you have to work with is very small. Sharing a chip with a few hundred other people has a down-side.

Still, people have done some fairly impressive things with it. The latest run has a Wolf3D-like renderer, a few simple CPUs, and a re-implementation of the AY-3-8913 sound chip.

I haven't done anything with it yet - my plans are too ambitious and will take a lot of preparation.

I looked there, but I could not found this:
Suppose, that I will make design (with 24 I/O pins etc, etc) and submit it there, then
- I will have to pay $300 and I will get (maybe year later) one black chip soldered on green PCB?
- what if I want just the chip, no PCB?
- what if I would like 2 (or 10) same chips, have I pay 2x (or 10x) the $300 and (maybe) submit my desing 2x (or 10x)?

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http://micro-corner.gilhad.cz/, http://8bit.gilhad.cz/6809/Expanduino/Expanduino_I.html, http://comp24.gilhad.cz/Comp24-specification.html, and many others

Must be a way around the IO and voltage limitations because the new replacement Z80 is on Tiny tapeout7, and Z80 is 5V and 40 pins.
https://github.com/rejunity/z80-open-silicon
Bill

For Z80 pin count, see the slide deck as linked in the README: three sets of 8 pins are multiplexed down to 8 I/Os.

Also addresses price: Three price levels: 100 QFN parts for $10k, 300 WSCP parts for $10k, or 1000 parts for $20k

Core voltage is 1.8v - perhaps the I/Os are 5V tolerant, but sounds like external regulation and level shifting might be needed.

A carrier board and demultiplexor will be needed for a 40 DIP replacement, but it's a fine idea for a project.

I'd love to get my hands on a simple sound chip like that...

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Glenn-in-France

Wasn't there a low pin-count version of the 6502?

There are a few 28 pin variants. The most popular being the 6507 - as used on about 30 million Atari 2600 video game consoles...

I built a little SBC out of one recently -

Picture here, but I've yet to do a proper write-up on it:

https://unicorn.drogon.net/IMG_20231220_193620_DRO.jpg

-Gordon

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Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/