Re: S/360

"Randy Hudson" <ime@[EMAIL PROTECTED]
> wrote in message
news:dqnbot$jb8$1@[EMAIL PROTECTED]
> In article <pqizf.1906$EU3.1442@[EMAIL PROTECTED]
>,
>  John W. Kennedy <jwkenne@[EMAIL PROTECTED]
> wrote:
>
> >>>> When I last looked, 27 + 1 + 7 + 1 = 36.
> >>> Are you under the impression that the 704 series had a 35-bit word
with
> >>> a parity bit?
> >>
> >> You said 36 bits earlier.
> >
> > Yes, I did, because it /did/ have 36. But your breakdown above
includes
> > an extra 1-bit field that cannot be accounted for.
>
> There's two sign bits: sign of mantissa, and sign of exponent.  "Excess"
> representation of the exponent hides the explicit sign, but the bit is
still
> effectively a sign.
>
> Also, with binary floating point, a normalized mantissa would always
have a
> 1 as the leftmost bit,

Except for zero.

> so in most implementations, that's assumed and
> overwritten by the sign bit.

Early float implementations did not do that.