27 Nov
2021
27 Nov
'21
3:22 a.m.
On Fri, Nov 26, 2021 at 3:32 PM Tom Ivar Helbekkmo via TUHS <
tuhs(a)minnie.tuhs.org> wrote:
Is there any relationship, other than pure coincidence, between this
naming scheme and DEC's F, G, and H floating
point number formats?
I don't think so. The System/360 letters referred specifically to the
amount of memory available, so a D compiler would run on a D machine with
256K, and E/F/G were 512K/1M/2M.
The DEC floats were an extension of Fortran's exponent letters: D=double,
E=generic, F=single. G is a variant of F with a different
mantissa/exponent balance, and H is double double. S and T floats came
later and were bit-for-bit compatible with IEEE binary32 and binary64
formats. Lisp went a different way: to D, E, F they added S for small
floats and L for large floats.