guard digit, is zero, the operands are equal. Neither
operand is changed as a result of the operation.
Exponent overflow, exponent underflow, or lost sig
nificance cannot occur.
Resulting Condition Code:
o Operands are equal
1 First operand is low
2 First operand is high
3
Program Interruptions:
Operation (if floating-point feature is not in
stalled)
Addressing (CD and CE only)
Significance
Programming Note
Numbers with zero fraction compare equal even when
they differ in sign or characteristic.Halve HER RR (Short Operands)
34
7 8 11 12 15
HDR RR (Long Operands)
24
7 8 11 12 15
The second operand is divided by two, and the
quotient is placed in the first operand location.
In short-precision, the low-order half of the result
register remains unchanged.
The operation shifts the fraction right one bit; the
sign and characteristic are not changed. No normaliza
tion or test for zero fraction takes place.
Condition Code: The code remains unchanged.
Program Interruptions:Operation (if floating-point feature is not in
stalled)
Specification
Programming Note
The halve operation differs from a divide operation
with the number two as divisor in the absence of pre
normalization and postnormalization and in the ab
sence of a zero-fraction test.Multiply MER RR (Short Operands) I 3C R] I R2 0 7 8 11 12 15
ME RX (Short Operands)
7C R]I X
2I B2
7 8 11 12 1516 1920 31
MDR RR (Long Operands)I 2C R] I R2 I 0 7 8 11 12 15
MD RX (Long Operands)I 6C R] I X
2I B2 0 7 8 11 12 1516 1920 31
The normalized product of multiplier (the second op
erand) and multiplicand (the first operand) replaces
the multiplicand.
The multiplication of two floating-point numbers
consists of a characteristic addition and a fraction
multiplication. The sum of the characteristics less 64 is
used as the characteristic of an intermediate product.
The sign of the product is determined by the rules of
algebra.
The product fraction is normalized by prenormaliz
ing the operands and postnormalizing the intermediate
product, if necessary. The intermediate product char
acteristic is reduced by the number of left-shifts. For
long operands, the intermediate product fraction is
truncated before the left-shifting, if any. For short
operands (six-digit fractions), the product fraction has
the full 14 digits of the long format, and the two low
order fraction digits are accordingly always zero.
Exponent overflow occurs if the final product char
acteristic exceeds 127. The operation is terminated,
and a program interruption occurs. The overflow ex
ception does not occur for an intermediate product
characteristic exceeding 127 when the final character
istic is brought within range because of normalization.
Exponent underflow occurs if the final product char-
Floating-Point Arithmetic 47
operand is changed as a result of the operation.
Exponent overflow, exponent underflow, or lost sig
nificance cannot occur.
Resulting Condition Code:
o Operands are equal
1 First operand is low
2 First operand is high
3
Program Interruptions:
Operation (if floating-point feature is not in
stalled)
Addressing (CD and CE only)
Significance
Programming Note
Numbers with zero fraction compare equal even when
they differ in sign or characteristic.
34
7 8 11 12 15
HDR RR (Long Operands)
24
7 8 11 12 15
The second operand is divided by two, and the
quotient is placed in the first operand location.
In short-precision, the low-order half of the result
register remains unchanged.
The operation shifts the fraction right one bit; the
sign and characteristic are not changed. No normaliza
tion or test for zero fraction takes place.
Condition Code: The code remains unchanged.
Program Interruptions:
stalled)
Specification
Programming Note
The halve operation differs from a divide operation
with the number two as divisor in the absence of pre
normalization and postnormalization and in the ab
sence of a zero-fraction test.
ME RX (Short Operands)
7C R]
2
7 8 11 12 1516 1920 31
MDR RR (Long Operands)
MD RX (Long Operands)
2
The normalized product of multiplier (the second op
erand) and multiplicand (the first operand) replaces
the multiplicand.
The multiplication of two floating-point numbers
consists of a characteristic addition and a fraction
multiplication. The sum of the characteristics less 64 is
used as the characteristic of an intermediate product.
The sign of the product is determined by the rules of
algebra.
The product fraction is normalized by prenormaliz
ing the operands and postnormalizing the intermediate
product, if necessary. The intermediate product char
acteristic is reduced by the number of left-shifts. For
long operands, the intermediate product fraction is
truncated before the left-shifting, if any. For short
operands (six-digit fractions), the product fraction has
the full 14 digits of the long format, and the two low
order fraction digits are accordingly always zero.
Exponent overflow occurs if the final product char
acteristic exceeds 127. The operation is terminated,
and a program interruption occurs. The overflow ex
ception does not occur for an intermediate product
characteristic exceeding 127 when the final character
istic is brought within range because of normalization.
Exponent underflow occurs if the final product char-
Floating-Point Arithmetic 47