Amps <- & -> Embedded
RISC-V has no I/O instructions. Memory mapped I/O on the soft core: the address map, a UART, and a boot menu driven by loads and stores.
The RISC-V core was Harvard by accident. Moving to a single von Neumann memory, and the store that ran the old instruction word once.
How to trust a CPU you wrote: tests you have seen fail, a single instruction encoder checked against the GNU assembler, and a RAM that was never there.
Building a tiny CPU from a program counter, memory, register file, ALU and control unit, until LEDs sweep along a row, and a double beat that was not a pipeline.
Why a firmware engineer went back to Mano's 1988 hardware design book and decided to build a RISC-V processor from scratch on an FPGA.