At the heart of the design is a 64-bit quad-core RV64GC processor running at 1.2GHz. The CPU powering the SiFive FU740 is an implementation of RISC-V that includes some optional features. However, designs based on the architecture do not have to be open source, and to produce physical CPUs you need a lot more money and resources than one typically thinks of when they hear the term “open source hardware.” Ordering up custom silicon isn’t quite as simple as getting a custom PCB made, at least not yet. It’s not licensed with an upfront costs and ongoing royalty payments in the way that, for example, Arm does things. What is RISC-V?Created by UC Berkeley in 2010, RISC-V is an open source Reduced Instruction Set Computer (RISC) instruction set architecture (ISA) that anyone is free to design a CPU around. The HiFive Unmatched’s claim to fame, its RISC-V CPU, compounded that feeling by pulling the rug of familiar CPU architectures out from under me and presenting a challenge when it came time to run the software I most commonly use on a daily basis. Even down to the little details like sitting on the floor in a basement reading guides that I'd have been helpless without. Seem familiar to any of you? My recent experience installing and running Ubuntu on the HiFive Unmatched development platform from SiFive really did evoke memories of that first taste of Linux. The day's 30 minutes of free dial-up from the local ISP are used to download 'tarballs' with 'Kermit.' Linux is strange and confusing, but I do like penguins. It's installed on a 486DX4 100 PC that lives in their poorly-lit, unfinished basement. I head over to my friend's house after class because a long-awaited CD with something called 'Slackware Linux' on it has arrived. The experience left me feeling a bit nostalgic. Experimenting with SiFive's HiFive Unmatched RISC-V development board over the last few weeks has felt a bit like stepping back in time.

Firefly pcb