[baybal2]

> Is that possible? I haven't crunched the numbers and I don't have enough information or context to do so accurately. But my gut says that it might depend on how many billionaires you're on good terms with.

130nm is quite ancient, but there are digital parts from early nineties still on the market. They are way bigger than 130nm.

Right now I have an ongoing project with a company making aircons. Their kit supplier uses a really, really ancient, and rare Hitachi MCU made on 600nm, and they are paying few dollars for it — more than some modern ARM SoCs.

They really want to change their kit supplier, or compel the chip supplier to cut cost, 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..

[pbourke]

> 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]

Yes, 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]

I wonder if you could run the firmware in emulation on a more recent CPU.

[baybal2]

I don't think one can even fund assembler docs for a chip so old, rare, and obscure as first SH-1,2,3 families.

[AlotOfReading]

This 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]

I'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.

[pbourke]

I 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

[baybal2]

That 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.