ICL 1900 Series Computers

Order Codes 13x

Octal Order Code Nmenonic Execution
130 FLOAT    N(M) Convert Fixed to Floating Point

The FLOAT instruction normalises the fixed mid-point number held in N(M) and N(M)+1 with respect to an exponent of 279, and loads the result into the floating-point accumulator A. The contents of N(M) and N(M)+1 are unaltered.

FOVR will be set if B0 of N(M)+1 is set to 1.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
131 FIX    N(M) Convert Floating Point to Fixed

The FIX instruction denormalises the contents of the floating-point accumulator A (i.e. it adjusts the exponent to 279) and alters the argument accordingly. The resulting number is stored in mid-point form in N(M) and N(M)+1, the contents of the floating-point accumulator A being undisturbed.

FOVR is used and remains unchanged. (See V below.)

C is not used and will be left clear.

V will be set if
1 the result is above the standard mid-point range, or
2 exponent overflow was indicated in the floating-point accumulator A.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
132 FAD  X  N(M) Floating Point Add

The FAD instruction causes the normalised floating-point number in N(M) and N(M)+1 to be added to the floating-point accumulator A. The contents of N(M) and N(M)+1 are unaltered. The result is left in A.

FOVR will be set if overflow occurs.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
133 FSB  X  N(M) Floating Point Subtract

If X=0 is specified, the normalised floating-point number in N(M) and N(M)+1 is subtracted from the contents of the floating-point accumulator A, the result being left in A.

If X=4 is specified, the contents of the floating-point accumulator A are subtracted from the normalised floating-point number in N(M) and N(M)+1, the result being left in A.

In both cases the contents of N(M) and N(M)+1 are unaltered.

FOVR will be set if exponent overflow occurs.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
134 FMPY  X  N(M) Floating Point Multiply

The FMPY instruction causes the contents of the floating-point accumulator A to be multiplied by the normalised floating-point number in N(M) and N(M)+1. The contents of N(M) and N(M)+1 are unaltered. The result is left in A.

FOVR will be set if exponent overflow occurs.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
135 FDVD  X  N(M) Floating Point Divide

If X=0 is specified, the contents of the floating-point accumulator A are divided by the normalised floating-point number in N(M) and N(M)+1, the result being left in A.

If X=4 is specified, the normalised floating-point number in N(M) and N(M)+1 is divided by the contents of A, the result being left in A.

In both cases the contents of N(M) and N(M)+1 are unaltered.

FOVR will be set if overflow occurs.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
136
(X=0)
LFP    N(M) Load Floating Point

The LFP instruction loads the floating-point accumulator A with the double length number in N(M) and N(M)+1. The contents of N(M) and N(M)+1 are unaltered.

FOVR will be set if B0 of N(M)+1 is set to 1.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
136
(X=1)
LFPZ Load Floating Point Zero

The LFPZ instruction clears the floating-point accumulator A and the exponent register.

FOVR is not used and is left clear.

C is not used and will be left clear.

V is not used and remains unchanged.

Modification This statement has no M field.
137
(X=0)
SFP    N(M) Store Floating Point

The SFP instruction clears the double length location N(M) and N(M)+1 and will load the area with the floating-point number in A. The contents of A are unaltered.

FOVR remains unaltered.

C is not used and will be left clear.

V is used and will be set if FOVR is set when the instruction comes to be obeyed.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.
137
(X=1)
SFPZ    N(M) Store Floating Point and Zeroise

The SFPZ instruction loads the contents of the floating-point accumulator A into store locations N(M). Accumulator A, FOVR and the exponent register are left clear.

FOVR will be left clear.

C is not used and will be left clear.

V is used and will be set if FOVR is set when the instruction comes to be obeyed.

Modification This statement has an M field. When modified, the least significant 15 bits of N + M are taken as the operand. In the extended data mode, the least significant 22 bits of N + M are taken as the operand.