[Info-vax] Current VMS engineering quality, was: Re: What's VMS up to these

[Michael Kraemer]

glen herrmannsfeldt schrieb:

> 
> Also, for S/360, an early C target after the PDP-11, floating point
> registers are double precision, though you can do single precision
> arithmetic on them. The single precision multiply instruction always
> generates a double precision product. It takes two extra instructions
> and one extra register to zero out the low bits of the product, as
> many compilers for other languages do.

Really?
Iirc there are the MDR and MER instructions, both operating on the same
register set (0,2,4,6), but in the single precision case only 32 bits
are used. It's easier than with IEEE, because the exponent is the same
(16**+-64).