I was curious about the following floating point (390, Z) issues. I
tried looking these things up in Z9 Principles of Operation but I
didn't understand some of the comments. Comments would be welcome.
1) "HFP" and "BFP". It appears that BFP "Binary Floating Point" is a
new instruction group. Could someone explain the difference to the
original HFP? I thought everything was stored in binary, and hex was
simply the external representation for us humans. Also, what are the
advantages of BFP? (I am not trying to do anything, just curious
about modern features.)
2) Super computer work:
From time to time IBM announces a new supercomputer for extremely
"industrial strength" calculations. These days they seem to be many
parallel processors of PC style architecture, not S/390.
On alt.folklore.computers, there seems to be an attitude of disdain
for using the S/390 mainframe for high powered number crunching. I'm
not sure why; some say it is because of poor rounding, normalization
or lack of "IEEE" compatibility, but the Pr of Op does cover all those
issues. Indeed, "normalized" instructions have been around since
System/360 days.
Our new Z9 seems to be extremely powerful. I would think a
production machine such as that might be cheaper and just as powerful
as a specially constructed machine.
If I understand the Pr of Op correctly, the standard "extended"
floating point allows 128 bits, or about 31 digits of precision. That
seems to be quite a bit. (That seems to date back to S/370 days 30
years ago, has the precision been extended since then with newer
machines?)
Would anyone like to comment on this? Thanks!
|
