It’a hard to make sense of these numbers.
For example, the article says $30 million to develop a 28nm chip.
First, surely it depends on how complex and how large the chip is. A chip consisting mostly of a Rocket core is going to be a very different cost to a Core i7, and a chip consisting almost entirely of SRAM different again.
Second, public press releases show that, as of about a year ago, SiFive has had $8.5m of funding, and yet has produced two chips, including a quad core 1.5 GHz one comparable to something like ARM A53 at 28nm.
Obviously, something doesn’t line up here.
Maybe one big factor is the difference between automatic and hand layout of the chip.
I noted a year ago that 320 MHz for the HiFive1’s FE310-G000 in 180nm is pretty good compared to most ARM chips topping out at 180 MHz in that process. However, back when Intel and Motorola were using 180nm for their flagship chips, they had both Pentium 3 and PowerPC G4 at 1.0 - 1.2 GHz. No doubt they spent an absolute fortune on manual layout and optimising pipeline stages in achieving that.