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This is false, the zXX microprocessors are custom cores that natively run the z/Architecture ISA. Even a trivial comparison will show they are different and not

This is false, the zXX microprocessors are custom cores that natively run the z/Architecture ISA. Even a trivial comparison will show they are different and not just a microcode layer running on a POWER processor. There is probably some level of sharing (say a high perf divide unit or whatever) but that doesn't make them the same. https://en.wikipedia.org/wiki/IBM_z14_(microprocessor) https://en.wikipedia.org/wiki/IBM_z14_(microprocessor) Edit, Adding some microarch descriptions links below: https://www.anandtech.com/show/11750/hot-chips-ibms-next-generation-z14-cpu-mainframe-live-blog-5pm-pt-12am-utc https://www.anandtech.com/show/11750/hot-chips-ibms-next-gen... https://en.wikichip.org/wiki/ibm/microarchitectures/power9 https://en.wikichip.org/wiki/ibm/microarchitectures/power9

justinjlynn 7y ago
They are custom cores, but they likely do share at least some RTL - we won't know, of course, unless IBM decide to share those details and I doubt they would.
lboc 7y ago
ISTR reading somewhere they're used in the I/O hardware (OSA etc)?
- StillBored 7y ago
  Yah, there are embedded power processors scattered all over IBM's hardware lines. The z tape controller a couple years ago was just a rack mount POWER server. OTOH, so is x86, the z's HMC, PE's etc are just x86 laptops/servers. But thats like calling an x86 server an ARM because there are ARM's in the disk controllers, and on the motherboard acting as BMC's/etc.
  - lboc 7y ago
    Agreed. I just read "...uses it..." to include things other than the main processors. (edit: misquote)
  - rbanffy 7y ago
    And mainframes rely on them extensively. Pretty much everything that can be delegated is, leaving the z cores running as little code as possible.
protomyth 7y ago
Their other mainframe product the iSeries is POWER-based. We just bought a new one and it has a POWER 9 CPU.
- StillBored 7y ago
  iseries is not a mainframe (and you will never hear an IBMer make that mistake). That's whats traditionally called a minicomputer. Sure they make some big ones, but people don't go around calling a superdome flex a mainframe either despite it being a massive machine (something like 1k cores and 48TB of ram in its max config). Its just a fancy x86.
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justinjlynn 7y ago

They are custom cores, but they likely do share at least some RTL - we won't know, of course, unless IBM decide to share those details and I doubt they would.

lboc 7y ago

ISTR reading somewhere they're used in the I/O hardware (OSA etc)?

StillBored 7y ago
Yah, there are embedded power processors scattered all over IBM's hardware lines. The z tape controller a couple years ago was just a rack mount POWER server. OTOH, so is x86, the z's HMC, PE's etc are just x86 laptops/servers. But thats like calling an x86 server an ARM because there are ARM's in the disk controllers, and on the motherboard acting as BMC's/etc.
- lboc 7y ago
  Agreed. I just read "...uses it..." to include things other than the main processors. (edit: misquote)
- rbanffy 7y ago
  And mainframes rely on them extensively. Pretty much everything that can be delegated is, leaving the z cores running as little code as possible.

protomyth 7y ago

Their other mainframe product the iSeries is POWER-based. We just bought a new one and it has a POWER 9 CPU.

StillBored 7y ago
iseries is not a mainframe (and you will never hear an IBMer make that mistake). That's whats traditionally called a minicomputer. Sure they make some big ones, but people don't go around calling a superdome flex a mainframe either despite it being a massive machine (something like 1k cores and 48TB of ram in its max config). Its just a fancy x86.

deleted 7y ago

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