abbreviating programs 73 ABS function 24, 143, 163 absolute addressing 118 absolute,X addressing 119 absolute,Y addressing 119 accounting 13 accumulator (A) 98 A register 122 accuracy loss of 13 ACK code 131 acknowledgements 1 ACS function 163 actions in flowcharts 21 ADC instruction 98, 181 add (+) operator 158 adding two-byte numbers in assembler 101 address memory 96 addressing modes 118 modes permitted 181 addressing modes: absolute 118 absolute,X 119 absolute,Y 119 immediate 103, 118 indexed 117, 119 indirect 120 post-indexed indirect 121 pre-indexed indirect 121 zero-page 119 zero,X 120 zero,Y 120 advanced graphics 79 algorithm Euclid's 35 AND (&) operator 15, 158 connective 30, 143 instruction 113, 182 Animals program 70 animated graphics 85 APPEND equivalent 142 appending text 142 apple tart recipe 20 Arbitrary Precision Powers program 55 arbitrary-precision arithmetic 47, 55 arrays AA to ZZ 45 assigning to 46 dimensioning a5 floating-point 161 in BASIC 45 multi-dimensional 50 of strings 62, 63 subscript checking for 50 | ASCII code for characters 59, 131 ASL instruction 115, 182 ASN function 163 assembler 99 compared with BASIC 95 delimiters ([ and ]) 171 formats 181 listing 100, 171 mnemonics 181 program 99 programming 95 syntax definition 202 assembly conditional 175 in-line 178 listing suppressing 173 two-pass 172 assigning to arrays 46 assignment (=) operator 12 string 58 asterisk (*) in COS commands 139 at (0) symbol 103, 118, 156 ATN function 163 backspace 132 backward references 172 baffled what to do if 91 base sixteen 96 ten 96 BASIC calculating in 11 characters and operators 155 compared with assembler 95 language 11 BASIC program writing a 23 BASIC statements, functions, and commands 143 syntax definition 199 BCC instruction 106, 182 BCS instruction 106, 182 BELL code 132 BEQ instruction 106, 182 BGET function 68, 144 binary conversion to 112 digits 111 notation 111 bistables 111 bit high-order 112 BIT instruction 183 bit least-significant 112 low-order 112 most-significant 112 bits 111 bleep 6, 132 Bleep program 114 bleep routine 125 |
Block Move program 178 block zero RAM 168 RAM locations 194 blocks file 10 BMI instruction 183 BNE instruction 106, 183 bounds of array or vector 92 BPL instruction 183 BPUT statement 67, 144 brackets 156 in BASIC programs 74 branches conditional 106 break flag 122 BREAK key 6 BRK instruction 174, 183 BS code 132 Bulls & Cows program 127 BVC instruction 183 BVS instruction 184 byte 98 indirection (?) operator 53, 158 byte vectors 53 dimensioning 53 bytes 112 for program free 24 calculating in BASIC 11 calculations fixed-point 13 floating-point 161 with money 13 Calculator program 137 call by reference using vectors 54 calls operating-system 192 CAN code 132 cancel 132, 155 carry flag 101, 108, 122 cassette database on 70 input from 68 interface setting up 8 operating system 139 output to 67 saving data on 68 cassette-interface signals 194 CAT command 9, 139 central processing unit 98 CH function 59, 97, 144 changing memory locations 15, 97 text spaces 135 character codes 134 extraction 59 return 59 character set 134 characters ASCII code for 59, 131 internal representation 97 inverted 131 printing special 64 Chequebook-Balancing program 39 circle of random hex characters |
84
CLC instruction 98, 184
CLD instruction 184
clear screen 6
CLEAR statement 28, 79, 144, 167
CLI instruction 184
clock plot 87
Clock program 85
CLV instruction 184
CMP instruction 109, 184
co-routines 42
codes control 65
cursor-movement 65
error 205
screen control 65
Coleridge 7
colour graphics 88, 167
COLOUR statement 167
comma (,) separator 156
in PRINT statement 12, 75
command abbreviations 73
commands 7
commands:
LIST 7, 149
LOAD 9, 135, 139, 149
NEW 7, 149
OLD 7
comments in assembler 172
in BASIC 24
compare in assembler 109
macro 178
concatenation of strings 61
conditional assembly 175
branches 106
conditions in BASIC 28
conjunctions AND and OR 30
connecting up 3
connections to ATOM 2
connectives:
AND 30, 143
OR 150
STEP 34, 153
THEN 30, 74, 153
TO 153
contents memory 96
control codes 65
control codes:
ACK 131
BELL 132
BS 132
CAN 132
CR 132
ESC 132
ETX 131
FF 132
HT 132
LF 132
NAK 132
RS 132
SI 132
|
SO 132 STX 131 control variable in assembler 109 in NEXT statement 75 conversion Arabic to Roman numerals 123 decimal to hexadecimal 96 hexadecimal to decimal 96 number-to-string 163 string-to-number 165 temperature 23 to binary 112 coordinates graphics 27 COPY key 133 COS 139 COS commands: CAT 9, 139 FLOAD 141 LOAD 139, 140 MON 141 NOMON 141 RUN 141 SAVE 139, 140 COS errors 142 function 163 COS messages disable 141 enable 141 COUNT function 145 counting in assembler 109 in flowcharts 19 CPU 98 CPX instruction 109, 184 CPY instruction 109, 185 CR code 132 CRC Signature program 93 CTRL (control) key 6, 194 key 140 Cubic Curve program 32 cursor 3 home 132 turn on/off 16 cursor-movement codes 65 curve Sierpinski 81 Curve Stitching in a Square program 34 curve stitching in 4 colours 88 curve three-dimensional 84 Cycloid program 166 DATA equivalent 63 data on cassette saving 68 Data to Cassette program 68 data types of 67 database on cassette 70 Day of Week program 62 debugging in assembler 176 DEC instruction 185 decimal mode flag 122 to hexadecimal conversion 96 decisions in flowcharts 18 | decoding 60 DEG function 164 delay random 38 DELETE key 6 deleting lines 7 delimiter statement 14 demonstration programs 4 DEX instruction 108, 185 DEY instruction 108, 185 Dice Tossing program 27 Digital Clock program 37 Waveform Processing program 48 DIM in assembler 99, 105 statement 45, 57, 145 dimensioning arrays 45 byte vectors 53 strings 57 disable COS messages 141 divide (/) operator 11, 158 DO statement 145 DO...UNTIL loop 34 double quote (") delimiter 155 DRAW statement 28, 80, 145 drawing lines 28 ear 113 editing screen 132 text 7 eight queens problem 44 Eight Queens program 44 enable COS messages 141 Encoder/Decoder program 60 encoding 60 END statement 145 EOR instruction 113, 185 equal (=) operator 29, 58, 158 equality string 58 equation root of 41 error codes 205 handler 137 ERROR message 8, 174 errors COS 142 floating-point 205 logical 91 NAME 10 SUM 10 syntax 91 tape 10 trapping 137 ESC code 132 key 7, 24, 106 escape 132, 155 ETX code 131 Euclid's algorithm 35 examining memory locations 97 examples graphics 81 exclusive-OR (:) operator 15, 158 execute file load and 141 executing machine-code 173 |
stored text 23 execution speed maximising 75 expansion memory 168 exponent 162 expression 143 EXT function 145 extension floating-point ROM 161 extraction character 59 factor 143 false logical value 31 Farenheit to Celsius program 23 faster FOR...NEXT loops 76 faults hardware 92 RAM memory 92 ROM memory 92 FDIM statement 162 FF code 132 FGET function 164 FIF statement 162 file blocks 10 handle 67 files named 139 text 9 unnamed 139 filter low-pass 49 FIN function 68, 146 find input 68 output 68 finish loading 141 FINPUT statement 162 First Twelve Powers of Two program 31 fixed-point calculations 13 flags status 122 flags: break 122 carry 101, 108, 122 decimal mode 122 interrupt disable 122 negative 122 overflow 122 zero 106, 108, 122 flip/flops 111 FLOAD command 141 floating-point arrays 161 calculations 161 errors 205 extension 161 floating-point functions: ABS 163 ACS 163 ASN 163 ATN 163 CDS 163 DEG 164 EXP 164 FGET 164 FLT 164 HTN 164 | LOG 164 PI 164 RAD 164 SGN 164 SIN 164 SQR 165 TAN 165 VAL 165 floating-point operators: indirection (!) 165 integer (%) 165 power (^) 165 floating-point program examples 166 representation 162 floating-point statements: FDIM 162 FIF 162 FINPUT 162 FPRINT 163 FPUT 163 FUNTIL 163 STR 163 floating-point variables 165 flowchart Guess a Number 30 puff pastry 20 sponge cake 18 symbols 21 flowcharts 17 actions in 21 counting in 19 decisions in 18 FLT function 164 FOR statement 33, 146 FOR...NEXT loop 33 graph plotting using 34 step size in 34 FOR...NEXT loops faster 76 format for graphics screeri 27 formfeed 132 forward references 107, 172 FOUT function 68, 146 FPRINT statement 163 FPUT statement 163 Fractional Multiplication program 178 free bytes for program 24 function abbreviations 73 functions string 58 trigonometrical 163 functions: ABS 24, 143 BGET 68, 144 CH 59, 97, 144 COUNT 145 EXT 145 FIN 68, 146 FOUT 68, 146 GET 68, 147 LEN 59, 148 |
PTR 151 RND 24, 152 FUNTIL statement 163 GCD algorithm 35 generating tone 25 GET function 68, 147 golden ratio 41 GOSUB statement 39, 135, 147 to labels 41 GOTO multi-way switch using 26 statement 25, 135, 147, with label 25 graph plotting using FOR...NEXT loop 34 graphics advanced 79 animated 85 colour 88 coordinates 27 examples 81 low-resolution 27 modes 79 origin 28 screen format for 27 graphics space 168, 169 graphics speed of 85 symbols 134 graphics symbols pr inting 65 graphics testing points in 87 greater-than (>) operator 29, 158 or equal (>=) operator 158 greater-than or equal operator 29 Greatest Common Divisor program 35 Guess a Number flowchart 30 program 29 hardware faults 92 Harpsichord program 124 hash (#) symbol 96 hexadecimal (&) operator 14, 96, 158 (#) operator 14, 96, 157 characters plotting 84 notation 14, 96 printing in 14 to decimal conversion 96 high-fidelity equipment testing 116 high-order bit 112 histogram plot 69 Histogram program 46 home cursor 132 horizontal tab 132 HT code 132 HTN function 164 IF statement 148 IF...THEN statement 28 | immediate addressing 103, 118 in-line assembly 178 INC instruction 185 increment macro 178 index registers 107, 122 routine 125 Index Routine program 118 index X register 107, 122 Y register 107, 122 indexed addressing 117, 119 indirect addressing 120 jump 120 indirection (!) operator 165 input from cassette 68 INPUT statement 23, 58, 14B input string 58 input/output parallel 169 ports 194 routines 191 inserting lines 7 instruction mnemonics 98, 181 instructions: ADC 98, 181 AND 113, 182 ASL 115, 182 BCC 106, 182 BCS 106, 182 BEQ 106, 182 BIT 183 BNI 183 BNE 106, 183 BPL 183 BRK 174, 183 BVC 183 BVS 184 CLC 98, 184 CLD 184 CLI 184 CLV 184 CMP 109, 184 CPX 109, 184 CPY 109, 185 DEC 185 DEX 108, 185 DEY 10S, 185 EOR 113, 185 INC 185 INX 108, 186 INY 108, 186 JMP 105, 186 JSR 102, 186 LDA 98, 186 LDX 107, 186 LDY 107, 187 LSR 115, 187 NOP 187 ORA 113, 187 PHA 187 PHP 187 PLA 188 |
PLP 188 ROL 116, 188 RTI 188 RTS 188 SBC 102, 189 SEC 102, 189 SED 189 SEI 189 STA 98, 189 STX 107, 189 STY 107, 190 TAX 109, 190 TAY 109, 190 TSX 190 TXA 110, 190 TXS 190 TYA 110, 190 integer (%) operator 165 interface printer 169 interrupt disable flag 122 vectors 193 interrupts 193 introduction 1 Invert String program 59 inverted characters 5, 131 letters 25 INX instruction 108, 186 INY instruction 108, 186 iteration in BASIC 31 iterative loop in assembler 108 JNP instruction 105, 186 JSB instruction 102, 186 jump indirect 120 jumps in assembler 105 keyboard 2, 5, 131 keys: BREAK 6 COPY 133 CTRL 140 CTRL (control) 6, 194 DELETE 6 ESC 7, 24, 106 LOCK 5, 131 REPT (repeat) 6, 194 RETURN 6 screen editing 133 SHIFT 5, 131, 140, 194 labels a to z 25, 156 GOSUB to 41 in assembler 105, 171 language BASIC 11 LDA instruction 98, 186 LDX instruction 107, 186 LDY instruction 107, 187 learning program 70 least-significant bit 112 left-string extraction 61 | LEN function 59, 148 length of a string 59 less-than (<) operator 29, 158 or equal (<=) operator 158 less-than or equal (<=) operator 29 LET statement 74, 148 letters lower-case 5 LF code 132 line numbers 6 Linear Interpolation program 41 linefeed 132 lines deleting 7 drawing 28 inserting 7 multi-statement 14, 75 LINK statement 100, 149, 173 LIST command 7, 149 listing assembler 100, 171 load and execute file 141 LOAD command 9, 135, 139, 140, 149 loading finish 141 location counter (P) 92, 171 locations memory 95 LOCK key 5, 131 LOG function 164 logical errors 91 operations 15, 112 logical value false 31 true 31 logical variables 31 loop DO...UNTIL 34 FOR...NEXT 33 loops in assembler 108 in BASIC 33 mis-nested 36 nested 36 loss of accuracy 13 loudspeaker 114 low-order bit 112 low-pass filter 49 low-resolution graphics 27 lower text space 168 lower-case letters 5 LSR instruction 115, 187 machine-code executing 173 in BASIC 123 program 100 macro compare 178 increment 178 parameters 177 macros in assembler 177 manipulations string 59 mantissa 162 map memory 195 Mastermind game 126 matrices representation of 51 using vectors of vectors 56 |
maximising execution speed 75 memory address 96 expansion 168 faults RAM 92 faults ROM 92 locations 95 memory locations changing 15, 97 examining 97 peeking 15 poking 15 memory map 195 screen 15 Memory Test program 92 memory testing 92 messages: ERROR 8, 174 OUT OF RANGE 107 PLAY TAPE 9, 68, 140 RECORD TAPE 9, 68, 141 REWIND TAPE 10, 140 mid-string extraction 61 mis-nested loops 36 mnemonic assembler 171 mnemonics 181 instruction 98 modes addressing 118 graphics 79 MON command 141 money calculations with 13 most-significant bit 112 MOVE statement 28, 80, 149 multi-dimensional arrays 50 multi-statement lines 14, 75 multi-way switch using GOTO 26 multiply (*) operator 11, 158 music 113, 124 random 115 mystery quotation 60 NAK code 132 NAME error 10 named files 139 negative flag 122 nested loops 36 NEW command 7, 149 new line (') 156 printing 14 NEXT statement 33, 149 statement control variable in 75 noise generation 116 on screen 168 noise-free plotting 154 NOMON command 141 NOP instruction 187 not equal (<>) operator 29, 158 notation binary 111 hexadecimal 96 number-to-string conversion 163 numbers random 24 | numeric data reading 64 field width 156 OLD command 7 statement 150 ON ERROR GOTO equivalent 137 op code 98 operating system 131 operating-system calls 192 routines 191 vectors 193 operation code 98 operations logical 15, 112 operators: add (+) 158 AND (&) 15, 158 assignment (=) 12 byte indirection (?) 53, 158 divide (/) 11, 158 equal (=) 29, 58, 158 exclusive-OR (:) 15, 158 greater-than (>) 29, 158 greater-than or equal (>=) 158 greater-than or equal (>=) 29 hexadecimal (&) 14, 96, 158 hexadecimal (#) 14, 96, 157 less-than (<) 29, 158 less-than or equal (<=) 158 less-than or equal (<=) 29 multiply (*) 11, 158 not equal (<>) 29, 158 OR \ 15, 158 pling (!) 156 query (?) 15, 53, 97 remainder (%) 11, 158 string ($) 57, 157 subtract (-) 11, 158 word indirection (!) 53, 156 OR \ operator 15, 158 connective 150 ORA instruction 113, 187 origin graphics 28 OSRDCH routine 102, 191 OSWRCH routine 102, 191 OUT OF RANGE message 107 output to cassette 67 overflow flag 122 page mode on/off 132 parallel input/output 169 parameters macro 177 PEEK statement equivalent 15 peeking memory locations 15 permitted addressing modes 181 permutation routine 52 perspective plottinq 83 PHA instruction 187 phi 41 PHP instruction 187 PI function 164 |
pixels 27, 79, 134 PIA instruction 188 PLAY TAPE message 9, 68, 140 pling (!) operator 156 plot clock 87 histoqram 69 Plot Histogram from Cassette program 69 PLOT statement 79, 150 Plotting Hex Characters program 84 plotting hexadecimal characters 84 in l3ASIC 87 noise-free 154 perspective 83 points 28 three-dimensional 83, 166 PLP instruction 188 point-plotting routine 88 points plotting 28 POKE statement equivalent 15 poking memory locations 15 to screen 16 port writing to 170 ports input/output 194 post-indexed indirect addressing 121 power (^) operator 165 Powers of Numbers program 36 of Two program 31, 48 pre-indexed indirect addressing 121 prime Numbers program 54 print Hex Digits program 176 Inverted String program 117 Registers on BRK program 174 PRINT statement 11, 150 statement comma in 12, 75 statement quotes in 12 print-field size (@) 13 printer end 131 interface 169 start 131 printing a character in assembler 102 graphics symbols 65 in hexadecimal 14 new line 14 special characters 64 str ing s 12, 58 the alphabet in assembler 110 prize 60 problem eight queens 44 processor 6520 98 program assembler 99 counter PC register 122 machine-code 100 planning a 17 programming service 93 | programs abbreviating 73 programs: Animals 70 Arbitrary Precision Powers 55 Bleep 114 Block Move 178 Bulls & Cows 127 Calculator 137 Chequebook-Balancing 39 Clock 85 CRC Signature 93 Cubic Curve 32 Curve Stitching in a Square 34 Cycloid 166 Data to Cassette 68 Day of Week 62 Dice Tossing 27 Digital Clock 37 Digital Waveform Processing 48 Eight Queens 44 Encoder/Decoder 60 Farenheit to Celsius 23 First Twelve Powers of Two 31 Fractional Multiplication 178 Greatest Common Divisor 35 Guess a Number 29 Harpsichord 124 Histogram 46 Index Routine 118 Invert String 59 Linear Interpolation 41 Memory Test 92 Plot Histogram from Cassette 69 Plotting Hex Characters 84 Powers of Numbers 36 Powers of Two 31, 48 Prime Numbers 54 Pr int Hex Dig its 176 Print Inverted String 117 Print Registers on BRK 174 Random Coloured Lines 168 Random Noise 116 Random Rectangles 80 Random Walk 65 Reaction Timer 37 Renumber 136 Replace 123 Roman Numerals 123 Rotating Rectangle 28 Saddle Curve 166 Sierpinski Curve 81 Simultaneous Equations 51 Sine and Tangent 166 Sorting 47 Square Root 35 Three-Dimensional Plotting 83 Tower of Hanoi 42 322 Hz 26 4-Colour Plot 88 prompt 3 |
pseudo-random sequence 116 PTR function 151 puff pastry recipe 19 PUT statement 67, 151 query (?) operator 15, 53, 97 quotation mystery 60 quoted strings 57 quotes in PRINT statement 12 RAD function 164 RAM block zero 168 memory faults 92 Random Coloured Lines program 168 random delay 38 music 115 Random Noise program 116 random number seed 152 numbers 24 Random Rectangles program 80 walk program 65 Reaction Timer program 37 READ equivalent 63 reading and writing data from BASIC 67 and writing speed of 70 numeric data 64 text 63 recipe analogy 17 apple tart 20 puff pastry 19 sponge cake 17 recipes subroutines in 20 RECORD TAPE message 9, 68, 141 recursion in BASIC 42 recursive subroutine calls 42 references backward 172 forward 172 registers index 107 registers: accumulator A 122 index X 107, 122 index Y 107, 122 program counter PC 122 stack pointer SP 122 status S 122 relational expression 143 operators 29 REM statement 24, 152 remainder (%) operator 11, 158 Renumber program 136 renumbering programs 136 using screen memory 136 Replace program 123 representation of matrices 51 REPT (repeat) key 6, 194 reset 6 return 132, 155 character 59 RETURN key 6 | statement 39, 152 REWIND TAPE message 10, 140 right-string extraction 61 RND function 24, 152 ROL instruction 116, 188 ROM extension 161 memory faults 92 Roman Numerals program 123 root of equation 41 ROR instruction 116, 188 rotate instructions 115 Rotating Rectangle program 28 rounding 13 routines in different text spaces 135 input/output 191 operating-system 191 routines: OSRDCH 102, 191 OSWRCH 102, 191 RS code 132 RTI instruction 188 RTS instruction 188 RUN command 141 statement 23, 135, 152 Saddle Curve program 166 SAVE command 139, 140 statement 9, 135, 139, 152 saving data on cassette 68 programs or text on tape 8 SBC instruction 102, 189 screen clear 6 control codes 65 editing 132 editing keys 133 end 132 format for graphics 27 mapping 134 memory 15 memory renumbering using 136 noise on 168 poking to 16 scrolling 6 start 131 scrolling screen 6 SEC instruction 102, 189 SED instruction 189 seed random number 152 SEI instruction 189 separator space as 155 service programming 93 SGET statement 68, 152 SGN function 164 Shell sort 47 shift instructions 115 SHIFT key 5, 131, 140, 194 SHUT statement 152 SI code 132 Sierpinski Curve program 81 |
signal sync 194 signals cassette-interface 194 Simultaneous Equations program 51 simultaneous equations solving 51 SIN function 164 Sine and Tangent program 166 SO code 132 solving simultaneous equations 51 sort Shell 47 Sorting program 47 space as separator 155 spaces in BASIC programs 74 special characters printing 64 speed of graphics 85 of reading and writing 70 sponge cake flowchart 18 recipe 17 SPUT statement 67, 153 SQR function 165 Square Root program 35 STA instruction 98, 189 stack pointer SP register 122 statement abbreviations 73 delimiter 14 terminator (;) 156 statements: BPUT 67, 144 CLEAR 28, 79, 144, 167 COLOUR 167 DIM 45, 57, 145 DO 145 DRAW 28, 80, 145 END 145 FOR 33, 146 GOSUB 39, 135, 147 GOTO 25, 135, 147 IF 148 IF...THEN 2S INPUT 23, 58, 148 LET 74, 148 LINK 100, 149, 173 MOVE 28, 80, 149 NEXT 33, 149 QlD 150 PLOT 79, 150 PRINT 11, 150 PUT 67, 151 REM 24, 152 RETURN 39, 152 RUN 23, 135, 152 SAVE 9, 135, 139, 152 SGET 68, 152 SeUT 152 SPUT 67, 153 UNTIL 153 WAIT 37, 153 status flags 122 S reg ister 122 status-reg ister flags 181 STEP connective 34, 153 | step size in FOR...NEXT loop 34 stopping a BASIC program 24 stored text executing 23 storing text 6 STR statement 163 string ($) operator 57, 157 assignment 58 equality 58 functions 58 input 58 length of a 59 manipulations 59 string right 143 string variables 57 string-to-number conversion 165 strings arrays of 62, 63 concatenation of 61 dimensioning 57 in BASIC 57 printing 12, 58 quoted 57 STX code 131 instruction 107, 189 STY instruction 107, 190 subroutines in BASIC 39 in recipes 20 uses of 40 subscript checking for arrays 50 substrings 61 subtract (-) operator 11, 158 subtraction in assembler 102 successive approximation 35 SUM error 10 suppressing assembly listing 173 switch using GOTO multi-way 26 switches in BASIC 26 symbols flowchart 21 sync signal 194 syntax definition 199 errors 91 TAB equivalent 145 TAN function 165 tape errors 10 saving programs or text on 8 TAX instruction 109, 190 TAY instruction 109, 190 teletype mode l31 temperature conversion 23 testable expression 143 testing high-fidelity equipment 116 memory 92 points in graphics 87 text editing 7 files 9 text space lower 168 upper 168 text spaces changing 135 routines in different 135 |
text storing 6 text-space pointer 135 three-dimensional curve 84 plotting 83, 166 Three-Dimensional Plotting program 83 timing BASIC lines 170 in BASIC 37 TO connective 153 tone generating 25 TOP function 24, 153 Tower of Hanoi program 42 trapping errors 137 trigonometrical functions 163 true logical value 31 TSX instruction 190 turn on/off cursor 16 two-pass assembly 172 TXA instruction 110, 190 TXS instruction 190 TYA instruction 110, 190 typewriter mode 131 unitialised variables 91 unnamed files 139 UNTIL statement 153 upper text space 168 VAL function 165 variables A to Z 12 floating-point 165 logical 31 string 57 | unitialised 91 VDU 133 vectors call by reference using 54 in BASIC 45 interrupt 193 of vectors 56 operating-system 193 versatile interface adapter 169 vertical tab 132 VIA 169 timers 170 visual display unit 133 VT code 132 WAIT statement 37, 153 what to do if baffled 91 word indirection (!) operator 53, 156 word vectors 53 writing a BASIC program 23 to port 170 zero flag 106, 108, 122 zero-page addressing 119 zero,X addressing 120 zero,Y addressing 120 322 Hz program 26 4-Colour Plot program 88 6520 processor 98 |