Remote-processing BASIC 52 Uživatelský manuál stáhnout pdf (Strana 161)

RPBASIC-52 PROGRAMMING GUIDE

D-1

APPENDIX D - Data storage

STRING STORAGE

BASIC-52 stores string variables between MTOP and top of variable space, call VARTOP. 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 terminated 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 variables: TEMP(5), PRESS(A)

Scalars are stored starting at VARTOP-1, with storage growing down at eight bytes per variable.

FLOATING-POINT FORMAT

RPBASIC-52 stores all floating-point numbers in a no rmalized pa cked binary-coded 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.

LOCATION

VALUE DESCRIPTION

X 88H exponent: 81H = 10

, 80H = 10

, 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 two digits

X-3 56H next least significant two digits

X-4 34H next most significant two digits

X-5 12H most significan t two digits

So we have .12345678 X 10

which is 12345678.

The POKEF comm and stores numbers in RA M in this same format. PE EKF e xpects to read a number in this

format.

1 2 ... 156 157 158 159 160 161 162 163

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Remote-processing BASIC 52 Uživatelský manuál Strana 161