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Comment by algorithm314 | Hacker News Reader

The ISA is epiphany or risc-v?

It's backward compatible with Epiphany-III...so it's still Epiphany ISA with new instructions.

I have read it but in the past he wrote a blog post that risc-v will be used as isa in future products.So maybe 64 bit risc-v with backwards compatibility with epiphane?(it sounds a bit strange)

I think a heterogeneous product was implied in that post, but I don't blame you for the confusion. The Epiphany-V is still homogeneous because of the time/funding constraints.

The Epiphany core is a co-processor, and the "main" processor is a couple of ARM cores to run Linux/other.

Maybe in the future they will offer boards with Risc-V main processors, and Epiphany co-processors.

I'm not sure how feasible 1024 Risc-V cores would be (although it sounds awesome). Epiphany cores were designed for this sort of thing.

Agree, but people have all kinds of pre-conceived notions about co-processors so let's clarify some things: e5 can't self-boot, doesn't have virtual memory management, and doesn't have hardware caching, but otherwise they are "real" cores. Each RISC core can run a lightweight runtime/scheduler/OS and be a host.

Jan Gray stuffed 400 RISC-V cores into a Xilinx Kintex UltraScale KU040 FPGA (and the KU115 is three times larger, not to mention the Virtex UltraScale range).

http://fpga.org/grvi-phalanx/

I have two excuses for why RISC-V didn't make it it. My February RISC-V post stated that we will use RISC-V in our next chip. We were already under contract for this chip so I was referring to the next chip from now. I had hopes of sneaking it into this chip, but ran out of time. Both lame excuses, I know. I am firmly committed to RISC-V in some form in the future. For clarity, I am not talking about replacing the Epiphany ISA with a RISC-V ISA.

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