Because they aren’t as open in reality as they sounded when announced.
The advantages of those two (and of ARM) is that there actual Implementations with decades of development behind them, Yes, some technical debt but also many painfully-learned good decisions.
RISC V, which I’m really excited about, you can think of as a PRD (customer’s perspective product requirements document). That’s what an ISA is. Each team builds to meet that using their own iomplemetation, none of which is more than a few years old yet. But the teams incorporate decades of learning , and have largely a blank sheet to start with. I think it will be great....but isn’t yet.
The advantages of those two (and of ARM) is that there actual Implementations with decades of development behind them, Yes, some technical debt but also many painfully-learned good decisions.
RISC V, which I’m really excited about, you can think of as a PRD (customer’s perspective product requirements document). That’s what an ISA is. Each team builds to meet that using their own iomplemetation, none of which is more than a few years old yet. But the teams incorporate decades of learning , and have largely a blank sheet to start with. I think it will be great....but isn’t yet.