Someone wrote: > Should we have machine instructions to compute a polynome of grade n? > I don't think so (but there were machines in the 60s which did just that, > and - in that period - they were faster by using such instructions).
VAX had polynomial evaluation in the 1980's, and it was well known to be slower than doing it with separate instructions. For that reason, it was likely rarely used, even if it got faster in later versions. The VAX instruction for doing subscript calculations, including bounds checking, was also known to be slower than doing the same thing without the special instruction. RISC or CISC, if some operation is done often enough it makes sense to have a special instruction. As Blaauw did much of the design of the S/360 architecture, in many cases he is criticizing himself. It would be rare for ED or EDMK to be used enough in a program to make a significant contribution to the CPU usage. (Most likely even in 1963.) Decisions that make sense one year might not the next. The S/360 instructions have done well over the years. -- glen
