The second example is a very large number
76655433222111118; refer to figure 5-15, frame B.
After the number has been put in exponent form, it, too,
will require two 32-bit words.
FLOATING-POINT PRECISION. Floating-
point formats include the use of single- and
double-precision (refer to figure 5-16, frames A and B).
The names single- and double-precision imply their
Notice the double-precision
floating-point format, two 32-bit words where the
characteristic is small compared to the mantissa in
which precision accuracy is required.
FLOATING-POINT ROUND. Floating-point
operations also include rounding instructions, which
are used for rounding the mantissas results; rounding
up when the mantissa is equal to or greater than one-half
of one and rounding down when it less than one-half of
one. Rounding can also be applied to double-length
results of mantissas.
If the sign bit is destroyed
(overflowed into) during mantissa rounding or division,
the computer will make corrections to the mantissa or
FLOATING-POINT INTERRUPTS. Float-
ing-point interrupts can be generated when retain
improper conditions are detected. The interrupts
inform the program of these conditions and permit
either notation or corrective procedures. Some
Underflow (negative excess) or overflow (posi-
tive excess)When a floating-point char-
acter exceeds an absolute value of 2N - 1 where
N is the msb.
Divisor Equals zero in a divide instruction
The control section will be notified and an interrupt
will be generated.
Figure 5-16.Floating-point numbers: A. Single precision; B. Double-precision.