TI stores floating point numbers according to this structure:
struct FP { byte sign; // Whether the number is positive or negative byte exponent; // Locates the decimal point byte significand[7]; // The number itself byte guard[2]; // Guard digits for mathematics };The magnitude of every real number except zero can be represented as m × 10^{exp}, where exp is an integer designating the exponent and m is a real number designating the significand such that 1 <= m < 10.
Examples:
$00, $9E, $23, $91, $80, $55, $75, $00, $00 2.391805575 × 10^{30} $80, $AC, $46, $19, $18, $45, $80, $00, $00 4.61918458 × 10^{44} $80, $77, $75, $16, $99, $60, $94, $17, $87 7.5169960941787 × 10^{7} $00, $89, $19, $80, $61, $22, $02, $65, $10 1980612202.6510
If the number is complex, then this number is the real part (a). The imaginary part (b) is held in the next consecutive OP register, which also has bits 2 and 3 of its sign byte set.
Example:
$0C, $7E, $22, $09, $78, $47, $30, $00, $00 0.0220978473  0.0012565562i $8C, $7D, $12, $56, $55, $62, $00, $00, $00
_Mov9ToOP1 _Mov9ToOP2 
Moves the nine bytes at HL to OP1 or OP2.  

INPUT  HL  Pointer to start of the nine bytes. 
DESTROYS  All but A  
Remarks  For complex numbers, use _Mov9OP1OP2, which moves the 18 bytes at HL to OP1 and OP2. 
LD HL, exp b_call(_Mov9ToOP1) RET exp: .DB $00, $80, $27, $18, $28, $18, $28, $45, $94 ;2.7182818284594
Routine  Effect 

_FPAdd  Adds OP2 to OP1. 
_FPDiv  Divides OP1 by OP2. 
_FPMult  Muliplies OP1 by OP2. 
_FPRecip  Reciprocal of OP1. OP2 = input OP1. 
_FPSub  Subtracts OP2 from OP1. 
_SqRoot  Square root of OP1. 
_Random  Gets a random number. 0.0 > OP1 > 1.0 
_OPxToOPy  Stores 11 bytes at OPx to OPy.  

DESTROYS  BC DE HL  
Remarks  These combinations are available:

_OPxExOPy  Swaps 11 bytes at OPx with 11 bytes at OPy.  

DESTROYS  A BC DE HL  
Remarks  These combinations are available:

_DispOP1A  Displays the floatingpoint number in OP1 using the small font, formatted using the current FIX setting.  

INPUT  OP1  Number 
A  Maximum number of characters (not digits) to display.  
DESTROYS  All 
_FormReal  Converts the number in OP1 into a string.  

INPUT  OP1  Number 
A  Maximum number of characters (not digits) to display, minimum of six.  
OUTPUT  BC  Length of string 
OP3  Start of string, nullterminated.  
DESTROYS  All  
Remarks  SCI, ENG, and FIX settings affect the string conversion. To ignore all format settings, use FormEReal. 
_ConvOP1  Converts the number in OP1 into a twobyte integer.  

INPUT  OP1  Number 
OUTPUT  DE  Converted number. 
Remarks  Generates an error if the exponent is greater than 3. 