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0 pointsuserbinator3y ago0 comments

I highly doubt it. As "reduced" as RISC-V is, 8051 is still tiny in comparison.

8051s are used in applications where a 4-bit MCU (yes, they do exist and are still in widespread use) is not quite enough, or they'd have chosen one of those instead.

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jpfr3y ago

There's a community doing "fpga golf". That is, reducing the number of LUT required to implement a CPU of a given ISA.

A basic RV32 CPU is down to 500-700 LUT.

    https://github.com/YosysHQ/picorv32
    https://github.com/olofk/serv

A minimal 8051 requires about 300 LUT.

    https://github.com/MicroCoreLabs/Projects/tree/master/MCL51

Not sure how this translates from an FPGA to a transistor count. But RV32 and 8051 should be within a factor of 2-3.

Taniwha3y ago

If all you're doing is making a core with a little ROM, a USB interface and a flash interface chances are your design is pad limited - it probably doesn't matter which CPU you use provided it's tinyish

(oh and 8051 are a pain to work with, they've taken far too much of my lifetime, they need the stake thru the heart thing)

snvzz3y ago

>If all you're doing is making a core with a little ROM, a USB interface and a flash interface

An interesting observation is that RV32 has excellent code density. Meaning, in this sort of scenario, the ROM could be much smaller, or fit way more code at the same size.

userbinatorOP3y ago

within a factor of 2-3

That's still a huge difference, and as I mentioned above, the 8051 is found in applications which are very sensitive to cost. In terms of gate count, the lowest numbers I could find for a RISC-V core are in the 10-20k range, while an 8051 goes down to 2.7k:

https://www.electronicsweekly.com/news/design/eda-and-ip/805...

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