Atari 400 Technical Reference Manual page 112

Clear FRO (ZFRO)
Function: This routine sets the contents of pseudo register FRO
to all zeros.
Calling
se~uence:
JSR ZFRO [OA44J
FRO
=
zero.
Clear Page Zero Floating Point Number (ZF1)
Function: This routine sets the contents of a zero-page floating
point number to all zeroes.
Calling
se~uence:
x
= Zero-page address of FP number to clear.
JSR ZFl [DA46J
Zero-page FP number(X) = zero.
Load Floating Point Number to FRO (FLOOR and FLOOP)
Function: These routines load pseudo register FRO with the
floating point number specified by the calling se~uence.
Calling se~uence$:
or
X,V = pointer (X
=
LSB) to FP number.
JSR FLDOR [DD89J
FLPTR
=
pointer to FP number.
JSR FLDOP [DD8DJ
FRO
=
floating point number (in either case).
FLPTR = pointer to FP number (in either case).
OPERATING SVSTEM C016555 -- Section 8
127