rascal@verdix.UUCP (Stephen Scalpone) (04/03/84)
Since the introduction of the VAX, two floating-point formats have been added, the "G" and "H" formats. Can someone explain to me when these types were introduced and on which processors? Thanks. Specifically, my old VAX 11/780 Architecture Handbook from 1977-78 lists two floating-point types, floating and double floating. The newer VAX-11 Architecture Reference Manual, Revision 6.1, May 20, 1982, lists these two types as "F" and "D" format. The two new types, "G" and "H" formats, are also given. Stephen Scalpone Verdix Corporation ogcvax!verdix!rascal sequent!verdix!rascal rascal.oregon-grad@csnet-relay
gwyn@brl-vgr.ARPA (Doug Gwyn ) (04/04/84)
G & H floating were added to the VAX-11/780 within the first year or so of its existence. They were intended to be IEEE standard compatible (I don't know if they ended up that way). On the 780 you have to buy some other option like user-WCS as a prerequisite; this is a botch. I think in general if you need more dynamic range than the PDP-11 compatible floating point format, you may get into trouble by simply using G & H instead (assuming you can do this in a simple way). Real production code that has to worry about exponents getting too large generally maintains its own scaling and adjusts things while running to keep within range.