The publication of the initial 1.0 frozen ISA spec was in mid 2019, five years ago. That was enough stuff for embedded devices, including basic Linux support.
A ton of instructions needed for more serious things -- vectors, hypervisor, crypto, cache control operations, more -- were published in December 2021, 2 1/2 years ago. The first chips with that spec (called RVA22) have been hitting the market in the last few months. An early Core i7 level chip with RVA22 will come out late this year, a Pentium III level (but 8 core) one is out now in the BPI-F3 and soon Milk-V Jupiter (MiniITX board).
A lot more almost as important instructions have been published since then. The RVA23 spec is about to be ratified in the next few months. That will be the likely LTS baseline for Android and other mobile and desktop OSes that you will see around 2026 or 2027, just as (hopefully) desktop-class (at least similar to Snapdragon X Elite) chips come out.
How long has RISC-V been around? Very little time. As of right now, it's four years behind Arm, with the gap closing.
Are you counting "real-world usage" as a measure? I can go to Costco or Best Buy right now and come home with a system with an ARM or x86-64 chip. I'd have to go out of my way to find a system with RISC-V at its core. Even if you allow for devices like routers or embedded systems in disk drives and the like, there's a good chance the selection that any given store has won't have a RISC-V.
Maybe you can come back to this comment in five or ten years and laugh at me, but right now it feels like RISC-V is a solution in search of a problem.
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)
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).
A ton of instructions needed for more serious things -- vectors, hypervisor, crypto, cache control operations, more -- were published in December 2021, 2 1/2 years ago. The first chips with that spec (called RVA22) have been hitting the market in the last few months. An early Core i7 level chip with RVA22 will come out late this year, a Pentium III level (but 8 core) one is out now in the BPI-F3 and soon Milk-V Jupiter (MiniITX board).
A lot more almost as important instructions have been published since then. The RVA23 spec is about to be ratified in the next few months. That will be the likely LTS baseline for Android and other mobile and desktop OSes that you will see around 2026 or 2027, just as (hopefully) desktop-class (at least similar to Snapdragon X Elite) chips come out.
How long has RISC-V been around? Very little time. As of right now, it's four years behind Arm, with the gap closing.