[Info-vax] OT: Halt and Catch Fire

[lists at openmailbox.org]

On Thu, 4 Jun 2015 11:46:42 +0000 (UTC)
glen herrmannsfeldt via Info-vax <info-vax at rbnsn.com> wrote:

> lists at openmailbox.org wrote:
> > There were (are?) only 3 opcodes that began with H. If I recall two were
> > floating point. I don't remember what the third was.
> 
> I don't usually think of them by their first letter. S/360 has a
> HALVE instruction for floating point, HER and HDR, for short and
> long floating point.  There is HIO, privileged Halt I/O instruction.

That might have been what I was thinking of but I admit to never having
used it. I figured you would remember the floating point opcode names.

> So many instructions have been added in ESA/390 and now z/ that I
> might expect some to start with H.

Yes. There have been way too many new opcodes added to z/Architecture. ESA
and S/390 were still very clean but z/Arch is a pizza with everything on
it. I don't know about the last few revisions but I have an earlyish z/OS
summary and HIO is gone but HSCH (HALT SUBCHANNEL) has been added. So,
still only three H opcodes.

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