18 Nov
2019
18 Nov
'19
10:42 p.m.
On Sun, Nov 17, 2019 at 12:14 AM Dave Horsfall <dave(a)horsfall.org> wrote:
On Sat, 16 Nov 2019, Peter Jeremy wrote:
The cat was already out and poking around with the publishing of: IBM 360
Principles of Operation, DOC A22-6821-0
<http://bitsavers.trailing-edge.com/pdf/ibm/360/princOps/A22-6821-0_360PrincOps.pdf>.
The
APL version of spec just gave it more area to roam.
More than just the instruction set - IBM
published a formal description
of the S/360 (in APL in the IBM Systems Journal issue that announced the
S/360). The S/360 was (I believe) the first case where a company
announced a computer architecture (rather than an implementation) and
implementations were expected to precisely comply with the architecture
(no more finding undocumented instructions and side-effects and writing
code that depended on them). This meant that clone makers could build a
clone that accurately emulated a S/360.
Ah, I'd forgotten about the APL documentation; thanks! Talk about giving
away the keys to the kingdom: Amdahl, Fujitsu, Hitachi...