Dennis Ritchie has died

19 Oct 2011

...
    When IBM wanted to port the IBM OS family to POWER,
they did the
 same thing.  (Z, in your list above.) 
 I argue this a little. Even though eClipz ostensibly "unified" the
 architectures with the POWER6 generation, z10 is descended from POWER6
 but is definitely not POWER. It still implements the z ISA and is still
 fully compatible with S/360.  
 See my long response to Dave McGuire on this topic.

 I'm not sure that what you say here really challenges my base assumption,
 since an emulator can be fully compatible with the hardware it replaces.
 I'm not stating that z/OS is running native on a POWER architecture, and
 I'm willing to be shown that it's not running on top of a hardware
 emulation layer, but nothing I've heard about it makes that any less
 probable. 
This is a bit like saying that Core microarch is only emulating x86
because of the underlying microops. IBM only unified the design in their
chips. They are based on similar internal design and z10 is derived
...
 from POWER6, but there is no "layer" turning
z ISA into Power ISA. It's z, through and through.

Wikipedia has a nice little article on it, but pull the IBM docs for
yourself.

-- 
------------------------------------ personal: http://www.cameronkaiser.com/ --
  Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- You'd PAY to know what you REALLY think. -- J. R. "Bob" Dobbs, 1961
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Dennis Ritchie has died