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> but the kit supplier itself can't migrate from Hitachi MCU because they don't have firmware sources as they themselves only copypasted the firmware as a binar
by pbourke 5y ago
> but the kit supplier itself can't migrate from Hitachi MCU because they don't have firmware sources as they themselves only copypasted the firmware as a binary for decades..
That’s seems like a rather existential problem. If I’m understanding correctly, the kit supplier makes the control board and the manufacturer does final assembly?
- baybal2 5y agoYes, and the Chinese kit supplier seemingly got the tech from a Japanese aircon maker somewhere in nineties, and then copied the board verbatim ever since.
- pbourke 5y agoI wonder if you could run the firmware in emulation on a more recent CPU.
- baybal2 5y agoI don't think one can even fund assembler docs for a chip so old, rare, and obscure as first SH-1,2,3 families.
- pbourke 5y agoI don’t know anything about these, but found it interesting that people have ported Linux to these chips as they’ve come off patent: https://en.m.wikipedia.org/wiki/SuperH#J_Core https://en.m.wikipedia.org/wiki/SuperH#J_Core
- baybal2 5y agoThat is for much more recent, and bigger cores. The one I talk about has a kilobyte of ROM, and is an original SuperH from early nineties.
- AlotOfReading 5y agoThis is a weird comment. One of the key features of the SuperH ISA is that it's more or less backwards compatible. I worked on them in the 00s/10s, but I can't imagine they had an entirely different ISA in the 90s. I also know that commercial SH3 emulators exist because I've used them. Heck, Renesas used to ship one with the toolchain.
- baybal2 5y agoI'm surprised to hear this, maybe trying to salvage the old binary might have had some sense, but the client already went for a complete re-engineering, recognising the low availability of this rare chip as a great threat.
- AlotOfReading 5y agoYeah, they definitely got rare in the normal supply chain. I'd be surprised to see one in anything other than a japanese design today.