Apple II User Manual

altered.  The A- and X-REGs are altered and the Y-REG is cleared.

Uses: MD1, MD2, MDEND.

Cautions: An exit to location $3F5 is taken if the quotient is less than

-2^128 or greater than +2^128-1

Notes: MD2 contains the remainder mantissa (equivalent to the MOD

function).  The remainder exponent is the same as the quotient exponent, or

1 less if the dividend mantissa magnitude is less than the divisor mantissa

magnitude.

Example: Prior to calling FDIV, FP1 contains -60 (dividend), and FP2

contains +12 (divisor).

      _____    _____    _____    _____

     |     |  |     |  |     |  |     |

FP1: | $85 |  | $80 |  |  0  |  |  0  |   (-60)

     |_____|  |_____|  |_____|  |_____|

       X1       M1

      _____    _____    _____    _____

     |     |  |     |  |     |  |     |

FP2  | $83 |  | $60 |  |  0  |  |  0  |   (+12)

     |_____|  |_____|  |_____|  |_____|

       X1       M1

After calling FMUL, FP1 contains -5 and M2 contains 0.

      _____    _____    _____    _____

     |     |  |     |  |     |  |     |

FP1: | $82 |  | $B0 |  |  0  |  |  0  |   (-5)

     |_____|  |_____|  |_____|  |_____|

       X1       M1

FLOAT Subroutine (address $F451)

Purpose: To convert integers to floating point representation.

Entry: A signed (two's complement) 2-byte integer is stored in M1

(high-order byte) and M1+1 (low-order byte).  M1+2 must be cleared by user

prior to entry.

Uses: NORM1.

Exit: The normalized floating point equivalent is left in FP1.  E, FP2,

SIGN, and SCR are not disturbed.  The A-REG contains a copy of the

high-order mantissa byte upon exit but the X- and Y-REGs are not disturbed.

The carry is cleared.

Notes: To float a 1-byte integer, place it in M1+1 and clear M1 as well as