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Your examples are all instruction sets that were developed with the idea in mind that they run together with the other instruction sets. What I meant with unrel

Your examples are all instruction sets that were developed with the idea in mind that they run together with the other instruction sets. What I meant with unrelated is instruction sets that have been developed independently and were not meant to run on the same cpu from the beginning. For instance a cpu that supports both the Risc-V and the Power architecture.

umanwizard 10y ago
Look again -- he mentioned Jazelle, does that fit the bill?
wolfgke 10y ago
> What I meant with unrelated is instruction sets that have been developed independently and were not meant to run on the same cpu from the beginning. Beside umanwizard's comment: What do you consider as "same CPU" here? As I wrote there exist SoCs that can execute multiple instruction sets (for example some DSP at the side of an ARM core, where both instruction sets were developed independently). Do you consider this as "the same CPU" or not and what is the reason why you say "yes" or "no" here?
spc476 10y ago
There was the V20/V30. It was a drop-in replacement for the 8088 that could also execute 8080 (or Z80---it's been awhile since I used one) code (it was also faster at executing 8088 code, which is why a lot of people used it). While the 8088 is descended from the 8080, it's not binary compatible (completely different opcodes) and probably fits your criteria.
- wolfgke 10y ago
  It was the Intel 8080 not the Z80 for which the V20/V30 had an emulation mode (just looked it up). To do some nitpicking on this great example: The Intel 8086/8088 was designed to be assembly source compatible (up to search & replace) to the Intel 8080 (source: https://en.wikipedia.org/w/index.php?title=Intel_8086&oldid=735318399#The_first_x86_design https://en.wikipedia.org/w/index.php?title=Intel_8086&oldid=...). People like legulere would thus clearly nitpick that the criterion "instruction sets that have been developed independently" is not satisfied here.

umanwizard 10y ago

Look again -- he mentioned Jazelle, does that fit the bill?

wolfgke 10y ago

> What I meant with unrelated is instruction sets that have been developed independently and were not meant to run on the same cpu from the beginning. Beside umanwizard's comment: What do you consider as "same CPU" here? As I wrote there exist SoCs that can execute multiple instruction sets (for example some DSP at the side of an ARM core, where both instruction sets were developed independently). Do you consider this as "the same CPU" or not and what is the reason why you say "yes" or "no" here?

spc476 10y ago

There was the V20/V30. It was a drop-in replacement for the 8088 that could also execute 8080 (or Z80---it's been awhile since I used one) code (it was also faster at executing 8088 code, which is why a lot of people used it). While the 8088 is descended from the 8080, it's not binary compatible (completely different opcodes) and probably fits your criteria.

wolfgke 10y ago
It was the Intel 8080 not the Z80 for which the V20/V30 had an emulation mode (just looked it up). To do some nitpicking on this great example: The Intel 8086/8088 was designed to be assembly source compatible (up to search & replace) to the Intel 8080 (source: https://en.wikipedia.org/w/index.php?title=Intel_8086&oldid=735318399#The_first_x86_design https://en.wikipedia.org/w/index.php?title=Intel_8086&oldid=...). People like legulere would thus clearly nitpick that the criterion "instruction sets that have been developed independently" is not satisfied here.