On a related note, I had always wished we at least got a complete PDF specification for the unreleased 65832, a 32-bit 6502 core. I'd love to implement it just for the novelty, even if nothing used it. http://www.mirkosoft.sk/65832.html
This made me wonder if anyone had designed a 64-but 6502. Came across this http://www.6502.org/users/andre/adv65/index.html which in turn links to many different things including a project that they had started on with making a 64-bit extension to 6502 for fun.
From skimming the datasheet, it looks like a fairly bad product. Sure the A register is extended to 32 bits, but the 8 bit data bus means that it's not going to be much faster than the 65816 and the address bus is still 24 bits. I have no clue why WDC decided to keep the same pinout as the 65816.
> I have no clue why WDC decided to keep the same pinout as the 65816.
The entire market for this new chip would have been 100% of the people with a 65816 and only those people. Companies do this for a couple reasons, last ditch effort to get cash flow or bridge a gap in a delayed product, extend a product line another cycle, etc.
Pinouts are powerful interfaces (semantically), look at the op-amp, what a wonderful design.
*edit, turns out this chip would have gone in last model of the Apple IIGS but it was the 65816 instead.
I find this stuff fascinating, how technologies fold and morph over time. Esp with MIPS pivoting into RISC-V.
Oh, it even has a datasheet! Thanks, that's amazing! The missing SEV instruction could have been aliased to SEP #$40. The only thing missing to produce a working replica today (in hardware or software, just for fun of course,) was indeed the XFE designation. The only place it could have gone was in the WDM prefix, but it could have been any byte after that. We would have to outright guess. He couldn't have reused XCE for it without risking perfect backward-compatibility (though of course he may have decided to do that anyway.)
That's really neat, I missed this on the previous runs I think. One of my very first computers was a KIM-1, I bought it from one of the security guards at a bank where I worked (as mail room sorter and mail runner).
Fond memories. The KIM ('keyboard input monitor') was a quirky little machine, with very little RAM but more general purpose IO than just about every computer today which led to a lot of real-world interface projects. I learned a ton from using it.
It is delightful to see the love of discovery and exploration unfold around an electronic dream: "What if I do X, Y, or Z?"
Where do people go to put their darlings to the test? Is there a place these radical designs compete to satisfy more than a personal curiosity posed as a "what if?" Some sort of Homebrew derby?
Various projects get shown off, plenty of boards built around retro (and quasi-retro) CPUs, some more audacious stuff like rebuilding the Apollo Guidance Computer.
The ultimate homebrew derby is those brave enough to make their designs available for sale, I suppose.
The KimKlone Microcomputer - https://news.ycombinator.com/item?id=26292235 - Feb 2021 (8 comments)
The KK Computer: A Radical 6502 Redesign - https://news.ycombinator.com/item?id=16564257 - March 2018 (8 comments)
Bride of Son of Cheap Video: The KimKlone - https://news.ycombinator.com/item?id=12468937 - Sept 2016 (2 comments)
The KimKlone: a radical 6502 redesign - https://news.ycombinator.com/item?id=3070169 - Oct 2011 (24 comments)