From: "DASDBILL2" <dasdbi...@comcast.net>
Sent: Saturday, November 15, 2014 2:03 AM
Eons ago, the decimal and floating point instruction sets, inter alia, were provided only for an
extra fee.
Except that the model 44 had the floating point instructions as standard.
The smaller models had only the basic set; I don't know whether they could (or
could not)
be fitted with those extra sets.
Incidentally, the model 30 of the System 4 (S/360 look-alike) had the
halfword instructions (no full-word instructions), including DH.
That may have been the reason why these instructions had their own separate
chapters
in the earliest versions of PoO. In later versions, after the instructions were
no longer
separately priced, they may have continued to be in separate chapters due to the inertia of
tradition.
