[flukus]

> The advantage to floating point math over fixed point is speed.

AFAIK this is only because modern CPU's have floating point units (https://en.wikipedia.org/wiki/Floating-point_unit), from memory these became common on home PCs around the time of the 486. A lot of early 3D games used fixed point because it was much faster for those that didn't have a co-processor installed.

Whether any of this is applicable to mainframes I don't know.

[lboc]

IBM hardware has supported packed decimal arithmetic for... ever? The z9 hardware onwards includes decimal floating point (IEEEsomethingorother) support[0] (sizeable PDF warning).

[0] http://publibfi.boulder.ibm.com/epubs/pdf/dz9zr011.pdf