initramfs
3 hours ago
"What is this processor? The SuperH processor is a Japanese design developed by Hitachi in the late 1990's. As a second generation hybrid RISC design it was easier for compilers to generate good code for than earlier RISC chips, and it recaptured much of the code density of earlier CISC designs by using fixed length 16 bit instructions (with 32 bit register size and address space), using microcoding to allow some instructions to perform multiple clock cycles of work. (Earlier pure risc designs used one instruction per clock cycle even when that served no purpose but to make the code bigger and exhaust the encoding space.)
Hitachi developed 4 generations of SuperH. SH2 made it to the United states in the Sega Saturn game console, and SH4 powered the Sega Dreamcast. They were also widely used in areas outside the US cosumer market, such as the japanese automative industry.
But during the height of SuperH's development, the 1997 asian economic crisis caused Hitachi to tighten its belt, eventually partnering with Mitsubishi to spin off its microprocessor division into a new company called "Renesas". This new company did not inherit the Hitachi engineers who had designed SuperH, and Renesas' own attempts at further development on SuperH didn't even interest enough customers for the result to go ito production. Eventually Renesas moved on to new designs it had developed entirely in-house, and SuperH receded in importance to them... until the patents expired."
mikepurvis
2 hours ago
Interesting point of history— the H8 processor is the MCU that powers the original Lego Mindstorms RCX. In high school I wrote some assembly language for it when making a robot that ran on BrickOS:
kn100
an hour ago
a slightly different (but close enough) Hitachi CPU also powered the Cybiko - a wacky games console few have heard of. I tried writing a disassembler for that particular cpu a while back. Was an interesting platform and oh man the documentation at least to me was gorgeous: github.com/kn100/cybemu/