"John W. Kennedy" <jwkenne@[EMAIL PROTECTED]
> wrote in message
news:vYypf.39224$L7.37622@[EMAIL PROTECTED]
> The guard digit was added to double precision, postnormalization was
> added to the HER and HDR instructions, and the behavior of overflow and
> underflow was altered.
The HE, HER, HD, HDR set was a glaring design error - a faux pas.
That it failed to post-normalise meant that it couldn't be used
in a loop to divide by, say, 32.
However, it could be used to divide by 2 etc effectively
by employing the DP version and following that by AD :
SDR o,o
LE 0,X
HDR 0,0
AD 0,zero
This was a pain, and to force folks to use that
to save some time compared with full division by 2
(between 10 and 30 times slower) was absurd,
because the memory available on the 360 was relatively small.
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