Radio Shack CTR-118 User Manual Page 130
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- Table of contents
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11-2
Speeding Up Execution
The speed at which a program is processed will depend on the complexity of
the operations and the number of instructions. In most simple programs,
speed will not be a factor. It will seem as though the answer is returned the
moment you enter RUN. However, as you begin writing longer and more
intricate programs, speed will become a significant factor. Here are some
suggestions to guide you in designing speedier programs.
1)
Delete all unnecessary lines in the program (REM statements, etc.)
2)
Combine multi-statement program lines when practical.
3)
Use variables rather than constants in operations (very important). Your
TRS-80 normally operates using floating decimal point values. It takes a lot
less time to access a variable than to convert a constant to floating point
representation. For example: if you will use
π
a lot in a program, define
π
as a
variable (PI=3.14159) and use the variable (PI) in the operations.
4)
Use POKE graphics. This can speed up your graphics displays by a factor
of 6.
5)
Define the most commonly used variables first. When a variable is
defined it is located at the top of the variable table. The second will be just
below that. When variables are accessed, the table will be searched to find
the variable. Therefore, you will save time by locating frequently used
variables at the top of the table (by defining them first). The Computer will
not have to look as far to find them.
6)
Use integer variables, especially in FOR-NEXT loops, when possible. This
is most important of all.
- LIMITED WARRANTY 2
- One Tandy Center 3
- Fort Worth, Texas 76102 3
- CONTENTS 5
- This Reference Manual and You 7
- Setting up the System 9
- Notes on Using the Recorder 10
- Special Notes: 11
- 1 / General Information 13
- Operating Modes 14
- Special Function Keys 15
- Variable Names 16
- Variable Types 16
- Arithmetic Operators 17
- Relational Operators 18
- String Operators 19
- Order of Operations 19
- Intrinsic Functions 20
- Graphics 20
- Error Messages 20
- Abbreviations 20
- Keyboard Rollover 21
- Glossary for LEVEL II BASIC 22
- 2 / Commands 23
- CLOAD? " 25
- CSAVE"1" 26
- CSAVE"A" 26
- DELETE 5 26
- DELETE 11-18 26
- 3 / Input-Output 31
- @ position, item list 33
- PRINT TAB 33
- (expression) 33
- PRINT USING 34
- PRINT #-1 42
- INPUT #-1 42
- Sample Program 43
- 10 INPUT#-1,A1,B$,L$ 43
- 20 PRINT A1,B$,L$ 43
- 40 GOTO 10 43
- 4 / Program Statements 45
- 10 DEFINT A,I,N 46
- 10 DEFINT I-N 46
- 100 DEFSNG I,W-Z 47
- 10 DEFDBL S-Z, A-E 47
- 10 DEFSTR L-Z 48
- 10 CLEAR 1000 48
- ON ERROR GOTO 57
- Data Conversion 62
- Typing of Constants 62
- Type Conversion 63
- 5 / Strings 67
- String Input/Output 68
- String Comparisons 69
- String Operations 70
- String Space 70
- (string) 71
- (string, n) 74
- STRING$ 76
- Coding/Decoding Program 78
- Instring Subroutine 78
- 6 / Arrays 81
- Other Types of Arrays 84
- 7 / Arithmetic Functions 89
- 100 K%=CINT(X#)+CINT(Y#) 90
- 100 Y=COS(X+3.3) 90
- 100 PRINT CSNG(A#+B#) 90
- 100 PRINT EXP(-X) 91
- 100 Y=ABS(A-FIX(A)) 91
- 100 Z=INT(A*100+.5)/100 91
- 100 PRINT LOG(3.3*X) 91
- 8 / Special Features 95
- ERR /2+1 98
- (address) 100
- CALL 0A7FH 103
- JP 0A9AH 103
- (variable name) 107
- Logical Operators 109
- 20 GOTO 10 111
- 9 / Editing 113
- ENTER key 114
- Space-bar 114
- 100 FOR I=1 TO 10_ 115
- 100 FOR I=_ 115
- L (List Line) 116
- X (Extend Line) 116
- I (Insert) 117
- A (Cancel and Restart) 117
- E (Save Changes and Exit) 117
- Q (Cancel and Exit) 118
- H (Hack and Insert) 118
- D (Delete) 118
- 100 FOR I=1 TO 1_ 119
- 10 / Expansion Interface 121
- Line Printer 122
- LPRINT CHR$(10) 124
- LINE ONE 124
- LINE TWO 124
- LINE THREE 124
- POKE 16424,40 125
- POKE 16425,0 125
- Mini-Disks - (DISK BASIC) 126
- Additions to LEVEL II 126
- Expansion of RAM Memory 127
- 11 / Saving Time and Space 129
- Speeding Up Execution 130
- Appendix 131
- A / Level II Summary 133
- Commands 135
- Input/Output Statements 138
- Program Statements 140
- String Functions 144
- Arithmetic Functions* 145
- Special Functions 146
- LEVEL II Reserved Words* 148
- B / Error Codes 151
- Explanation of Error Messages 152
- Hard-To-Find Errors 153
- C / TRS-80 Character Codes 155
- Decimal/Hexadecimal Codes 156
- Control Codes: 0-31 157
- Graphics Codes: 128-191 158
- Graphic Characters 161
- D / Memory Map 163
- Important Addresses 164
- F / Derived Functions 167
- G / Base Conversions 169
- H / User Programs 173
- Sort Routine 175
- Space-Ship Lander 176
- Customer Information 178
- Target Practice 180
- Using Your Cassette Deck 185
- LEVEL II 187
- Hints and Tips 187
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