Floating Point Add (FAD)/OP=80

Format

OP AF BF A Syllable B Syllable C Syllable

OP = 80

AF is the length of the A Syllable field Mantissa. The sign and exponent digits (4) are not included in this length. AF may be indirect or may indicate the A Syllable is a literal (if literal, the mantiss length is limited to two digits). A value of 00 is equal to a mantissa length of 100 units.
BF is the length of the B Syllable field Mantissa. The sign and exponent digits (4) are not included in this length. BF may be indirect. A value of 00 is equal to a mantissa length of 100 units.

The A Syllable is the address of the addend field. Address may be indexed, indirect or extended. The final address controller is ignored and the field assumed to be in floating point format.
The B Syllable is the address of the augend field. Address may be indexed, indirect or extended. The final address controller is ignored and the field assumed to be in floating point format.
The C Syllable is the address of the sum field. Address may be indexed, indirect or extended. The final address controller is ignored and the field assumed to be in floating point format.

Supported Models

Model Status
B3500 Supported
B4800 Supported
B2900/B3900/B4900 Supported
V-Series (All models) Unsupported

Function

After proper alignment of operands, a FAD instruction adds the contents of the A field to those of the B field and stores the sum in the C field.

Comparison Flags

In all cases except overflow, set the Comparison Flags to indicate whether the sum is greater than (HIGH), equal to (EQUAL) or less than (LOW) zero.

Overlap

A and B may totally overlap or may have matching type-address overlap (see 3.5.3). Partial overlap of A and B other than matching type-address overlap may produce incompatible results. See Compatibility Notes A.09.

Examples

Example (1) Add Two Floating Point Numbers

OP AF BF A Syllable B Syllable C Syllable
80 02 05 A field SN B field SN C Field SN
                    BEFORE         AFTER
  A FIELD          -04+20        unchanged
  B FIELD         -05+67501      unchanged
  C FIELD          nnnnnn        -05+67701
  COMPARISON          nn            HIGH
  OVERFLOW            nn         unchanged

Example (2) Add Two Floating Point Numbers, Overflow Condition

OP AF BF A Syllable B Syllable C Syllable
80 01 03 A field SN B field SN C field SN
                    BEFORE         AFTER
  A FIELD          +99+1         unchanged
  B FIELD          +99+999       unchanged
  C FIELD     nnnnnnnnnn         unchanged
  COMPARISON          nn            HIGH
  OVERFLOW            nn         On
instructions/fad.txt · Last modified: 2018/03/27 08:37 by scott
 
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