Thanks for the replies, much appreciated. We do have current processors, just my knowledge that is out of date :)
The factor might not be a whole number, which is why I thought of FP, but I can see I can follow the multiply by a 64 bit divide by 100 to get a percentage. I take it the 'G' instructions can be executed in 31 bit, due to their explicit naming (and no-one mentioned amode)? One question occurs - must I now use extended save areas, as I am doing something to the top halves of the GPRs, or will the system take care of that for me? (There are no amode 64 progs on the calling chain). Thanks, Joe
