[userbinator]

Despite how simple and limited the 6502 is, it's always interesting to see this almost 50-year-old architecture being stretched to new limits. 6502 cores are still found in some SoCs aimed at the ultra-low-cost high-volume market.

[dailykoder]

> 6502 cores are still found in some SoCs aimed at the ultra-low-cost high-volume market.

What's the reason behind that? Probably just keeping existing, working designs and thus saving R&D costs? Sounds like beating a 10 cent risc-v core would be hard.

Edit: When I first read your comment I had to chuckle a bit, because I got the image of a multicore SoC with 6502 6502 cores. That would be a fun project for my FPGA hmmmmmmmm ...

[themoonisachees]

10c per part is incredibly high depending on how low-cost we're talking.

If your chip needs very basic processing, and you're going to sell it for less than a cent per chip, you need your core to be basically free.

Sure RISC-V is very inexpensive, but for parts like these risc is massive overkill and as a modern core, you'll be spending a lot of die area on a core that should really be an ASIC, but designing an ASIC is expensive so you can just slap a 6502 in that bad boy and call it a day.

On the other end of the scale, you'd be surprised to learn that many chips you don't ever interface with as a user contain even ARM cores. These are usually ASICs in high-end products.

[snvzz]

>but for parts like these risc is massive overkill

You seem to underestimate how small a RISC-V core can be.

Take a look at SERV.

[monocasa]

The area of just the register file (even for rv32e) is higher area than the survivors of the 8 bit ucontrollers.

[userbinator]

16 registers * 32 bits * 4 transistors / cell = 2k transistors just for storing the bits alone, and that's not including the decoding and read/write circuitry.

[snvzz]

There is no need to do weird math, as we know the actual numbers.

6502 has 3510 transistors. SERV at CMOS occupies 2.1kGE.

SERV is smaller than 6502.

[snvzz]

Not true for SERV vs 6502.

SERV is smaller.

[irdc]

There’s also the cost of rewriting (yes, from assembler) all the existing code. And don’t forget QA.

[jeffgreco]

Go on!

[utensil4778]

A lot of cheap USB1/2 widgets are actually a 6800 core. It's crazy how these old CPUs have stuck around for so long

[ddingus]

There is a ton of code out there for pretty much any task you want.

I have the 16 bit successor, the 65816, on a variable speed expansion card in my Apple 2. I run it in 8 bit mode most of the time mostly because it works and most library code is 8 bit.

At those speeds, the chip is fast! Especially when one considers the simple model: ram clocked 1:1 with the cpu. In my case, I can run code over the 1Mhz bus, essentially turning most multi cycle ops into a single bus cycle per memory fetch.

Or, the card has a megabyte of RAM and that runs at CPU speed. (0.15 to 16 Mhz) When doing that, it is fast enough to run large programs, written in higher level languages, at a useful speed. Of course Assembly language is crazy fast.

It is a pretty fun environment to hack around in.