From: "glen herrmannsfeldt" <[email protected]> Sent: Tuesday, 30 August 2011 6:14 PM
The book "Computer Architecture: Concepts and Evolution" by Blaauw and Brooks has many descriptions on how instructions got to be the way they did. The book covers a wide variety of machines, though S/360 is a favorite example. (Blaauw was the main designer of S/360, so it isn't so surprising.) There is a small description of EDIT in section 5.1.3. They trace back to "Store for Print" on the 702. Then explain that EDIT
The instruction is ED, not EDIT,; its companion is EDMK.
is rarely used by COBOL or Fortran for print conversions,
That's probably because the instruction was optional on the small early models of S/360 and the software was written to use basic instructions. Nevertheless, there's no reason for not using it, because the small machines that didn't have those instructions have long since passed to computer heaven. That said, I understand that IBM 360 compilers didn't use TRT, which IIRC was a standard instruction. BTW, EDMK was used for all decimal output in the optimising XPL compiler.
and that it is best that it should be left out of instruction sets.
A bad recommendation, because so much is done by ED and EDMK, and with little effort and even less overhead compared with alternatives.
If you like asking questions like that, especially for a variety of different machines, you should get the book.
I wouldn't bother, if that is the level of its advice.
