[prezk]

apparently all Western Digital drives have a RISC-V controller, as well as NVIDIA graphic cards https://riscv.org/wp-content/uploads/2016/07/Tue1100_Nvidia_...

WCH makes a microcontroller that sells for around 10 cents; it's cheaper than a 7400 quad gate, so it's bound to end up in a ton of things. It occurred to me that they are like electric motors: unglamorous but ubiquitous (there are several dozen electric motors, mostly small ones, in the room I am sitting in right now)

[brucehoult]

Yeah. To get that 12.4c CH32V003 price (for an 8 pin package) you need to spend $6.21 on 50 of them. If you want to replace a 7400 quad 2-input NAND then you'll need to buy the 16 pin package which is 16.3c each for 50 ($8.30 in total)

On Digikey the cheapest I can find SOIC14 7400s is 20c each, but you have to buy 1480 of them to get that. If you want just a few they're $1.60 each, and if you want DIP14 they're $2.

The propagation delay of using a microcontroller to implement a quad NAND gate will be a lot higher than the 7400's 14ns of course. At a wild guess I'd say 200ns or greater. Could be 1us. I don't think more than that. That's still fine for many uses.

For those who don't know, a CH32V003 is a 32 bit RISC-V CPU implementing the RV32EC instruction set (basic integer instructions, 16 registers, 2-byte instructions available for the most common operations, as well as the standard 4-byte instructions, to save 25%-30% program space. It has 2048 bytes of RAM and 16k of flash memory to hold your program. A program to emulate a 7400 would use 0 of the RAM and maybe 100 bytes of the flash (most of it would be init code, run once at power-on).