Remote Processing BASIC 52 - Manual (Page 161)

RPBASIC-52 PROGRAMMING GUIDE
D-1
APPENDIX D - Data storage
STRING STORAGE
BASIC-52 stores string variables between MTO P and top of variable space, call VARTO P. String $(0) would be
stored from VARTOP to [VARTOP + (bytes_per_string + 1)]. String $(1) is stored from [VARTOP +
(bytes_per_string + 2)] to [VARTOP +2 * (bytes_per_string + 1)], and so on.
All strings are term inated with a c arriage return (0D H, 13 decim al).
VARIABLE STORAGE
Scaler variables are numbers not in a dimension. Dimensioned or arrayed variables (commonly referred to as
"arrays") are those whose identifier includes a single-dimensioned expression.
Scaler variables: PAR T, A1 , B
Dimensioned va riables: T E M P ( 5) , P R E S S (A )
Scalars are stored starting at VARTO P-1, with storage growing down at eight bytes per variable.
FLOATING-POINT FORMAT
RPB ASIC-5 2 stores all floating-point nu mbers in a no rmalized pa cked binary-co ded decim al (BCD ) format. All
numbers are normalized, so the most significant digit in a floating-point number is never zero unless its actual
value is zero.
To demonstrate the floating-point format, see how RPBASIC-52 stores 12345678.
L O C A T I O N V A L U E D E S C R I PT I O N
X 88H exponent: 81H = 10 1 , 80H = 10 0 , 7FH = 10 -1 , etc.
Zero is represented by a zero exponent
X-1 00H sign bit: 00H = positive, 01H = negative
Other bits are temporary values used only during calculations
X-2 78H least significant tw o digits
X-3 56H next least significan t two digits
X-4 34H next most sig nificant two digits
X-5 12H most significan t two digits
So we have .12345678 X 10 8 which is 12345678.
The PO KEF c omm and stores num bers in RA M in this sam e format. PE EKF e xpects to read a number in th is
format.