Phison PS2303 (PS2251-03) framework
Here's one with a 250MHz 8051: https://github.com/flowswitch/phison/wiki/PS2303
They don't need anything as powerful as ARM (and thus avoid the licensing fees), and it's a very price-sensitive market, so a fast 8051 + accelerator hardware is enough.
No doubt some of the more expensive ones may be ARM-based, but I think the 8051-based ones far outsell them in volume.
PicoRV32 - A Size-Optimized RISC-V CPU
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.
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SERV - The SErial RISC-V CPU
Ted Fried's MicroCore Labs Projects which include microsequencer-based FPGA cores and emulators for the 8088, 8086, 8051, 6502, 68000, Z80, Risc-V, and also Typewriter and EPROM Emulator projects. MCL51, MCL64, MCL65, MCL65+, MCL68, MCL86, MCL86+, MCL86jr, MCLR5, MCLZ8 (by MicroCoreLabs)
There is a difference, but not much!
How many LUT for an 8 bit CPU?
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Minimax: a Compressed-First, Microcoded RISC-V CPU
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I have created a Reddit community about PicoBlaze soft processor...
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Efinix and Xyloni Board - Heard a lot of clients mention them, so took a look.
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