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F/Scren1
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_19.ADF |
| Filename: | F/Scren1 |
| Read OK: | ✔ |
| File size: | 1416 bytes |
| Load address: | 53204556 |
| Exec address: | 6E657263 |
File contents
Programming the opening screen.
I needed an opening screen this time because no-one has sent
anything.
This is how I did it.
10MODE6 Fairly obvious but necessary because some of the
positioning statements later wouldn't work as expected in
another mode. Try changing the MODE to say MODE2 to see what
I mean.
20CLS This makes sure that the screen is clear before
starting. Again remove this line to see the effect.
30VDU23,1,0;0;0;0; This turns off the flashing cursor.
40PRINTTAB(11,4)"NEWS, OPINIONS,"
50PRINTTAB(13,6)"PROGRAMMING"
60PRINTTAB(12,8)"IT'S YOUR EUG"
These lines print the heading statement. The TAB(ii,dd)
after PRINT makes sure that the words are printed in
particular positions. ii is the position in from the left
hand side while the dd is the position down from the top of
the screen.
70B%=10000 This is a variable, an integer variable infact.
An integer variable can hold any whole number. I used this
because I needed a number later on for the computer to
count up to before it did something, rather like counting
up to 100 when you play hide and seek, you do play don't
you?
80FOR A= 1TO 8 This line starts what is known as a FOR NEXT
loop. Now it says 'there is a variable called A. This
variable is initially equal to 1. The following lines should
be executed by the computer in the normal way until the
computer finds an instruction NEXT A. At this point A will
equal 2 and the computer should return to the line defining
the start of the FOR NEXT loop, in this case line 80 and
then execute all the instructions again.' It will continue to
do this adding 1 to A each time untill A = 8 when it will
leave the loop and start executing any instructions after
the NEXT A command.
If you type in 10FOR A= 1 TO 10
20PRINT"EUG"A
30NEXT A
40PRINT"Done"
then RUN this you will see EUG printed on the screen 10
times. After EUG will be written a number equal to A so that
you will have a sequence of EUG's. Line 40 will not be
executed untill the FOR NEXT loop has finished so it will
only be printed once at the end of the program.
The FOR NEXT loop is one of the most fundamental commands in
BASIC. Indeed loops similar to this are the most fundemental
commands on any computer including multi-million pound
machines.
90READ A$ The READ command tells the computer to look into
DATA statements, and what ever is in there to put this into
the variable following the READ command. In this case the
DATA statements have text in them so the variable is A$ the
$ is pronounced dollar. A $ variable is used for text and is
more properly called a string variable since a sequence of
text is known as a string
%, pronounced percent, variable is used for whole numbers.
% variable is properly called an interger variable.
A variable without a sign is called a real variable and
can be used for whole numbers and fractions.
I used real variables simply to save some time typing but
sometimes it is necessary to use an integer variable for
example when the counting in the FOR NEXT loop might
produce a fraction which you want the computer to ignore.
The first DATA statement is read on the first pass of the
loop, on the second pass the second DATA statement is read
an so on.
100PRINTTAB(1,12)A$ This simply tells the computer to print
A$ whatever it happens to be at that time in a particular
position.
110PRINTTAB(1,19)" This line would offend most BASIC
programmers. It prints a blank line in a particular position
which is used further down the program. So when this
position has something written onto it later on in the
program, the loop cycles around and executes this line again
and this line effectivly erases this position.
There are more elegant ways of doing this but this works
quite well and.....
120FORT%=1 TO B% This is another FOR NEXT loop. This time
its purpose is simply to make the computer wait for a while
before executing the next instruction because it has to
count up to 10000 which is what B% is equal to. In this
case its purpose is to make some time to read A$ from line
100. Again there are more elegant ways to do this but....
The variable B% is used because when I was developing the
program I wanted to make it run quite fast. I didn't need to
read A$ since I had written A$. During development I was
setting B% to 100.This trick is used again later on so
that delays are all of the same length.
130NEXTT% See above.
140READ B$ This is exactly the same as the READ A$. But in
this case it will be the next DATA statement down.
150PRINTTAB(1,19)B$ Again the same as line 100 but notice
that the position for printing is different.
160PRINTTAB(1,12)" This puts a blank line in the position
where A$ was printed. A$ is erased and so B$ looks like a
reply to A$.
170FORT%=1 TO B%
180NEXTT% This is an identical delay to lines 120
and 130
190NEXT A This is the end of the original FOR NEXT loop. the
computer will add one to A and then go back to line 80 to
loop through the instructions again until of course A = 8
00000000 50 72 6f 67 72 61 6d 6d 69 6e 67 20 74 68 65 20 |Programming the | 00000010 6f 70 65 6e 69 6e 67 20 73 63 72 65 65 6e 2e 0d |opening screen..| 00000020 0d 49 20 6e 65 65 64 65 64 20 61 6e 20 6f 70 65 |.I needed an ope| 00000030 6e 69 6e 67 20 73 63 72 65 65 6e 20 74 68 69 73 |ning screen this| 00000040 20 74 69 6d 65 20 62 65 63 61 75 73 65 20 6e 6f | time because no| 00000050 2d 6f 6e 65 20 68 61 73 20 73 65 6e 74 20 0d 61 |-one has sent .a| 00000060 6e 79 74 68 69 6e 67 2e 0d 0d 54 68 69 73 20 69 |nything...This i| 00000070 73 20 68 6f 77 20 49 20 64 69 64 20 69 74 2e 0d |s how I did it..| 00000080 0d 31 30 4d 4f 44 45 36 20 46 61 69 72 6c 79 20 |.10MODE6 Fairly | 00000090 6f 62 76 69 6f 75 73 20 62 75 74 20 6e 65 63 65 |obvious but nece| 000000a0 73 73 61 72 79 20 62 65 63 61 75 73 65 20 73 6f |ssary because so| 000000b0 6d 65 20 6f 66 20 74 68 65 20 0d 70 6f 73 69 74 |me of the .posit| 000000c0 69 6f 6e 69 6e 67 20 73 74 61 74 65 6d 65 6e 74 |ioning statement| 000000d0 73 20 6c 61 74 65 72 20 77 6f 75 6c 64 6e 27 74 |s later wouldn't| 000000e0 20 77 6f 72 6b 20 61 73 20 65 78 70 65 63 74 65 | work as expecte| 000000f0 64 20 69 6e 20 0d 61 6e 6f 74 68 65 72 20 6d 6f |d in .another mo| 00000100 64 65 2e 20 54 72 79 20 63 68 61 6e 67 69 6e 67 |de. Try changing| 00000110 20 74 68 65 20 4d 4f 44 45 20 74 6f 20 73 61 79 | the MODE to say| 00000120 20 4d 4f 44 45 32 20 74 6f 20 73 65 65 20 77 68 | MODE2 to see wh| 00000130 61 74 20 0d 49 20 6d 65 61 6e 2e 0d 0d 32 30 43 |at .I mean...20C| 00000140 4c 53 20 54 68 69 73 20 6d 61 6b 65 73 20 73 75 |LS This makes su| 00000150 72 65 20 74 68 61 74 20 74 68 65 20 73 63 72 65 |re that the scre| 00000160 65 6e 20 69 73 20 63 6c 65 61 72 20 62 65 66 6f |en is clear befo| 00000170 72 65 20 0d 73 74 61 72 74 69 6e 67 2e 20 41 67 |re .starting. Ag| 00000180 61 69 6e 20 72 65 6d 6f 76 65 20 74 68 69 73 20 |ain remove this | 00000190 6c 69 6e 65 20 74 6f 20 73 65 65 20 74 68 65 20 |line to see the | 000001a0 65 66 66 65 63 74 2e 0d 0d 33 30 56 44 55 32 33 |effect...30VDU23| 000001b0 2c 31 2c 30 3b 30 3b 30 3b 30 3b 20 54 68 69 73 |,1,0;0;0;0; This| 000001c0 20 74 75 72 6e 73 20 6f 66 66 20 74 68 65 20 66 | turns off the f| 000001d0 6c 61 73 68 69 6e 67 20 63 75 72 73 6f 72 2e 0d |lashing cursor..| 000001e0 0d 34 30 50 52 49 4e 54 54 41 42 28 31 31 2c 34 |.40PRINTTAB(11,4| 000001f0 29 22 4e 45 57 53 2c 20 20 20 4f 50 49 4e 49 4f |)"NEWS, OPINIO| 00000200 4e 53 2c 22 20 0d 35 30 50 52 49 4e 54 54 41 42 |NS," .50PRINTTAB| 00000210 28 31 33 2c 36 29 22 50 52 4f 47 52 41 4d 4d 49 |(13,6)"PROGRAMMI| 00000220 4e 47 22 20 0d 36 30 50 52 49 4e 54 54 41 42 28 |NG" .60PRINTTAB(| 00000230 31 32 2c 38 29 22 49 54 27 53 20 59 4f 55 52 20 |12,8)"IT'S YOUR | 00000240 45 55 47 22 20 20 0d 54 68 65 73 65 20 6c 69 6e |EUG" .These lin| 00000250 65 73 20 70 72 69 6e 74 20 74 68 65 20 68 65 61 |es print the hea| 00000260 64 69 6e 67 20 73 74 61 74 65 6d 65 6e 74 2e 20 |ding statement. | 00000270 54 68 65 20 54 41 42 28 69 69 2c 64 64 29 20 0d |The TAB(ii,dd) .| 00000280 61 66 74 65 72 20 50 52 49 4e 54 20 6d 61 6b 65 |after PRINT make| 00000290 73 20 73 75 72 65 20 74 68 61 74 20 74 68 65 20 |s sure that the | 000002a0 77 6f 72 64 73 20 61 72 65 20 70 72 69 6e 74 65 |words are printe| 000002b0 64 20 69 6e 20 0d 70 61 72 74 69 63 75 6c 61 72 |d in .particular| 000002c0 20 70 6f 73 69 74 69 6f 6e 73 2e 20 69 69 20 69 | positions. ii i| 000002d0 73 20 74 68 65 20 70 6f 73 69 74 69 6f 6e 20 69 |s the position i| 000002e0 6e 20 66 72 6f 6d 20 74 68 65 20 6c 65 66 74 20 |n from the left | 000002f0 0d 68 61 6e 64 20 73 69 64 65 20 77 68 69 6c 65 |.hand side while| 00000300 20 74 68 65 20 64 64 20 69 73 20 74 68 65 20 70 | the dd is the p| 00000310 6f 73 69 74 69 6f 6e 20 64 6f 77 6e 20 66 72 6f |osition down fro| 00000320 6d 20 74 68 65 20 74 6f 70 20 6f 66 20 0d 74 68 |m the top of .th| 00000330 65 20 73 63 72 65 65 6e 2e 0d 0d 37 30 42 25 3d |e screen...70B%=| 00000340 31 30 30 30 30 20 54 68 69 73 20 69 73 20 61 20 |10000 This is a | 00000350 76 61 72 69 61 62 6c 65 2c 20 61 6e 20 69 6e 74 |variable, an int| 00000360 65 67 65 72 20 20 76 61 72 69 61 62 6c 65 20 69 |eger variable i| 00000370 6e 66 61 63 74 2e 0d 41 6e 20 69 6e 74 65 67 65 |nfact..An intege| 00000380 72 20 76 61 72 69 61 62 6c 65 20 63 61 6e 20 68 |r variable can h| 00000390 6f 6c 64 20 61 6e 79 20 77 68 6f 6c 65 20 6e 75 |old any whole nu| 000003a0 6d 62 65 72 2e 20 49 20 75 73 65 64 20 74 68 69 |mber. I used thi| 000003b0 73 20 0d 62 65 63 61 75 73 65 20 49 20 10 6e 65 |s .because I .ne| 000003c0 65 64 65 64 20 61 20 6e 75 6d 62 65 72 20 20 6c |eded a number l| 000003d0 61 74 65 72 20 6f 6e 20 66 6f 72 20 74 68 65 20 |ater on for the | 000003e0 63 6f 6d 70 75 74 65 72 20 74 6f 20 0d 63 6f 75 |computer to .cou| 000003f0 6e 74 20 75 70 20 74 6f 20 62 65 66 6f 72 65 20 |nt up to before | 00000400 69 74 20 10 64 69 64 20 73 6f 6d 65 74 68 69 6e |it .did somethin| 00000410 67 2c 20 72 61 74 68 65 72 20 6c 69 6b 65 20 63 |g, rather like c| 00000420 6f 75 6e 74 69 6e 67 20 0d 75 70 20 74 6f 20 31 |ounting .up to 1| 00000430 30 30 20 77 68 65 6e 20 79 6f 75 20 70 6c 61 79 |00 when you play| 00000440 20 68 69 64 65 20 61 6e 64 20 10 73 65 65 6b 2c | hide and .seek,| 00000450 20 79 6f 75 20 64 6f 20 70 6c 61 79 20 64 6f 6e | you do play don| 00000460 27 74 20 0d 79 6f 75 3f 0d 0d 38 30 46 4f 52 20 |'t .you?..80FOR | 00000470 41 3d 20 31 54 4f 20 38 20 54 68 69 73 20 6c 69 |A= 1TO 8 This li| 00000480 6e 65 20 73 74 61 72 74 73 20 77 68 61 74 20 69 |ne starts what i| 00000490 73 20 6b 6e 6f 77 6e 20 61 73 20 61 20 46 4f 52 |s known as a FOR| 000004a0 20 4e 45 58 54 20 0d 6c 6f 6f 70 2e 20 4e 6f 77 | NEXT .loop. Now| 000004b0 20 69 74 20 73 61 79 73 20 27 74 68 65 72 65 20 | it says 'there | 000004c0 69 73 20 61 20 76 61 72 69 61 62 6c 65 20 63 61 |is a variable ca| 000004d0 6c 6c 65 64 20 41 2e 20 54 68 69 73 20 0d 76 61 |lled A. This .va| 000004e0 72 69 61 62 6c 65 20 69 73 20 69 6e 69 74 69 61 |riable is initia| 000004f0 6c 6c 79 20 65 71 75 61 6c 20 74 6f 20 31 2e 20 |lly equal to 1. | 00000500 54 68 65 20 66 6f 6c 6c 6f 77 69 6e 67 20 6c 69 |The following li| 00000510 6e 65 73 20 73 68 6f 75 6c 64 20 0d 62 65 20 65 |nes should .be e| 00000520 78 65 63 75 74 65 64 20 62 79 20 74 68 65 20 63 |xecuted by the c| 00000530 6f 6d 70 75 74 65 72 20 69 6e 20 74 68 65 20 6e |omputer in the n| 00000540 6f 72 6d 61 6c 20 77 61 79 20 75 6e 74 69 6c 20 |ormal way until | 00000550 74 68 65 20 0d 63 6f 6d 70 75 74 65 72 20 66 69 |the .computer fi| 00000560 6e 64 73 20 61 6e 20 69 6e 73 74 72 75 63 74 69 |nds an instructi| 00000570 6f 6e 20 4e 45 58 54 20 41 2e 20 41 74 20 74 68 |on NEXT A. At th| 00000580 69 73 20 70 6f 69 6e 74 20 41 20 77 69 6c 6c 20 |is point A will | 00000590 0d 65 71 75 61 6c 20 32 20 61 6e 64 20 74 68 65 |.equal 2 and the| 000005a0 20 63 6f 6d 70 75 74 65 72 20 73 68 6f 75 6c 64 | computer should| 000005b0 20 72 65 74 75 72 6e 20 74 6f 20 74 68 65 20 6c | return to the l| 000005c0 69 6e 65 20 64 65 66 69 6e 69 6e 67 20 0d 74 68 |ine defining .th| 000005d0 65 20 73 74 61 72 74 20 6f 66 20 74 68 65 20 46 |e start of the F| 000005e0 4f 52 20 4e 45 58 54 20 6c 6f 6f 70 2c 20 69 6e |OR NEXT loop, in| 000005f0 20 74 68 69 73 20 63 61 73 65 20 6c 69 6e 65 20 | this case line | 00000600 38 30 20 61 6e 64 20 0d 74 68 65 6e 20 65 78 65 |80 and .then exe| 00000610 63 75 74 65 20 61 6c 6c 20 74 68 65 20 69 6e 73 |cute all the ins| 00000620 74 72 75 63 74 69 6f 6e 73 20 61 67 61 69 6e 2e |tructions again.| 00000630 27 20 49 74 20 77 69 6c 6c 20 63 6f 6e 74 69 6e |' It will contin| 00000640 75 65 20 74 6f 20 0d 64 6f 20 74 68 69 73 20 61 |ue to .do this a| 00000650 64 64 69 6e 67 20 31 20 74 6f 20 41 20 65 61 63 |dding 1 to A eac| 00000660 68 20 74 69 6d 65 20 75 6e 74 69 6c 6c 20 41 20 |h time untill A | 00000670 3d 20 38 20 77 68 65 6e 20 69 74 20 77 69 6c 6c |= 8 when it will| 00000680 20 0d 6c 65 61 76 65 20 74 68 65 20 6c 6f 6f 70 | .leave the loop| 00000690 20 61 6e 64 20 73 74 61 72 74 20 65 78 65 63 75 | and start execu| 000006a0 74 69 6e 67 20 61 6e 79 20 69 6e 73 74 72 75 63 |ting any instruc| 000006b0 74 69 6f 6e 73 20 61 66 74 65 72 20 0d 74 68 65 |tions after .the| 000006c0 20 4e 45 58 54 20 41 20 63 6f 6d 6d 61 6e 64 2e | NEXT A command.| 000006d0 0d 0d 49 66 20 79 6f 75 20 74 79 70 65 20 69 6e |..If you type in| 000006e0 20 31 30 46 4f 52 20 41 3d 20 31 20 54 4f 20 31 | 10FOR A= 1 TO 1| 000006f0 30 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |0. | 00000700 20 32 30 50 52 49 4e 54 22 45 55 47 22 41 0d 20 | 20PRINT"EUG"A. | 00000710 20 20 20 20 20 20 20 20 20 20 20 20 20 20 33 30 | 30| 00000720 4e 45 58 54 20 41 0d 20 20 20 20 20 20 20 20 20 |NEXT A. | 00000730 20 20 20 20 20 20 34 30 50 52 49 4e 54 22 44 6f | 40PRINT"Do| 00000740 6e 65 22 0d 0d 74 68 65 6e 20 52 55 4e 20 74 68 |ne"..then RUN th| 00000750 69 73 20 79 6f 75 20 77 69 6c 6c 20 73 65 65 20 |is you will see | 00000760 45 55 47 20 70 72 69 6e 74 65 64 20 6f 6e 20 74 |EUG printed on t| 00000770 68 65 20 73 63 72 65 65 6e 20 31 30 20 0d 74 69 |he screen 10 .ti| 00000780 6d 65 73 2e 20 41 66 74 65 72 20 45 55 47 20 77 |mes. After EUG w| 00000790 69 6c 6c 20 62 65 20 77 72 69 74 74 65 6e 20 61 |ill be written a| 000007a0 20 6e 75 6d 62 65 72 20 65 71 75 61 6c 20 74 6f | number equal to| 000007b0 20 41 20 73 6f 20 74 68 61 74 20 0d 79 6f 75 20 | A so that .you | 000007c0 10 77 69 6c 6c 20 10 68 61 76 65 20 10 61 20 10 |.will .have .a .| 000007d0 73 65 71 75 65 6e 63 65 20 10 6f 66 20 10 45 55 |sequence .of .EU| 000007e0 47 27 73 2e 20 4c 69 6e 65 20 34 30 20 77 69 6c |G's. Line 40 wil| 000007f0 6c 20 6e 6f 74 20 62 65 20 0d 65 78 65 63 75 74 |l not be .execut| 00000800 65 64 20 10 75 6e 74 69 6c 6c 20 10 74 68 65 20 |ed .untill .the | 00000810 10 46 4f 52 20 10 4e 45 58 54 20 6c 6f 6f 70 20 |.FOR .NEXT loop | 00000820 68 61 73 20 66 69 6e 69 73 68 65 64 20 73 6f 20 |has finished so | 00000830 69 74 20 77 69 6c 6c 0d 6f 6e 6c 79 20 62 65 20 |it will.only be | 00000840 70 72 69 6e 74 65 64 20 6f 6e 63 65 20 61 74 20 |printed once at | 00000850 74 68 65 20 65 6e 64 20 6f 66 20 74 68 65 20 70 |the end of the p| 00000860 72 6f 67 72 61 6d 2e 0d 0d 54 68 65 20 46 4f 52 |rogram...The FOR| 00000870 20 4e 45 58 54 20 6c 6f 6f 70 20 69 73 20 6f 6e | NEXT loop is on| 00000880 65 20 6f 66 20 74 68 65 20 6d 6f 73 74 20 66 75 |e of the most fu| 00000890 6e 64 61 6d 65 6e 74 61 6c 20 63 6f 6d 6d 61 6e |ndamental comman| 000008a0 64 73 20 69 6e 20 0d 42 41 53 49 43 2e 20 49 6e |ds in .BASIC. In| 000008b0 64 65 65 64 20 6c 6f 6f 70 73 20 73 69 6d 69 6c |deed loops simil| 000008c0 61 72 20 74 6f 20 74 68 69 73 20 61 72 65 20 74 |ar to this are t| 000008d0 68 65 20 6d 6f 73 74 20 66 75 6e 64 65 6d 65 6e |he most fundemen| 000008e0 74 61 6c 20 0d 63 6f 6d 6d 61 6e 64 73 20 6f 6e |tal .commands on| 000008f0 20 61 6e 79 20 63 6f 6d 70 75 74 65 72 20 69 6e | any computer in| 00000900 63 6c 75 64 69 6e 67 20 6d 75 6c 74 69 2d 6d 69 |cluding multi-mi| 00000910 6c 6c 69 6f 6e 20 70 6f 75 6e 64 20 0d 6d 61 63 |llion pound .mac| 00000920 68 69 6e 65 73 2e 0d 0d 39 30 52 45 41 44 20 41 |hines...90READ A| 00000930 24 20 54 68 65 20 52 45 41 44 20 63 6f 6d 6d 61 |$ The READ comma| 00000940 6e 64 20 74 65 6c 6c 73 20 74 68 65 20 63 6f 6d |nd tells the com| 00000950 70 75 74 65 72 20 74 6f 20 6c 6f 6f 6b 20 69 6e |puter to look in| 00000960 74 6f 20 0d 44 41 54 41 20 73 74 61 74 65 6d 65 |to .DATA stateme| 00000970 6e 74 73 2c 20 61 6e 64 20 77 68 61 74 20 65 76 |nts, and what ev| 00000980 65 72 20 69 73 20 69 6e 20 74 68 65 72 65 20 74 |er is in there t| 00000990 6f 20 70 75 74 20 74 68 69 73 20 69 6e 74 6f 20 |o put this into | 000009a0 0d 74 68 65 20 76 61 72 69 61 62 6c 65 20 66 6f |.the variable fo| 000009b0 6c 6c 6f 77 69 6e 67 20 74 68 65 20 52 45 41 44 |llowing the READ| 000009c0 20 63 6f 6d 6d 61 6e 64 2e 20 49 6e 20 74 68 69 | command. In thi| 000009d0 73 20 63 61 73 65 20 74 68 65 20 0d 44 41 54 41 |s case the .DATA| 000009e0 20 73 74 61 74 65 6d 65 6e 74 73 20 68 61 76 65 | statements have| 000009f0 20 74 65 78 74 20 69 6e 20 74 68 65 6d 20 73 6f | text in them so| 00000a00 20 74 68 65 20 76 61 72 69 61 62 6c 65 20 69 73 | the variable is| 00000a10 20 41 24 20 74 68 65 20 0d 24 20 69 73 20 70 72 | A$ the .$ is pr| 00000a20 6f 6e 6f 75 6e 63 65 64 20 64 6f 6c 6c 61 72 2e |onounced dollar.| 00000a30 20 41 20 24 20 76 61 72 69 61 62 6c 65 20 69 73 | A $ variable is| 00000a40 20 75 73 65 64 20 66 6f 72 20 74 65 78 74 20 61 | used for text a| 00000a50 6e 64 20 69 73 20 10 0d 6d 6f 72 65 20 70 72 6f |nd is ..more pro| 00000a60 70 65 72 6c 79 20 63 61 6c 6c 65 64 20 61 20 73 |perly called a s| 00000a70 74 72 69 6e 67 20 76 61 72 69 61 62 6c 65 20 73 |tring variable s| 00000a80 69 6e 63 65 20 61 20 73 65 71 75 65 6e 63 65 20 |ince a sequence | 00000a90 6f 66 0d 74 65 78 74 20 69 73 20 6b 6e 6f 77 6e |of.text is known| 00000aa0 20 61 73 20 61 20 73 74 72 69 6e 67 20 20 20 20 | as a string | 00000ab0 0d 25 2c 20 70 72 6f 6e 6f 75 6e 63 65 64 20 70 |.%, pronounced p| 00000ac0 65 72 63 65 6e 74 2c 20 10 76 61 72 69 61 62 6c |ercent, .variabl| 00000ad0 65 20 69 73 20 75 73 65 64 20 66 6f 72 20 77 68 |e is used for wh| 00000ae0 6f 6c 65 20 6e 75 6d 62 65 72 73 2e 20 20 0d 25 |ole numbers. .%| 00000af0 20 76 61 72 69 61 62 6c 65 20 69 73 20 10 70 72 | variable is .pr| 00000b00 6f 70 65 72 6c 79 20 63 61 6c 6c 65 64 20 61 6e |operly called an| 00000b10 20 69 6e 74 65 72 67 65 72 20 76 61 72 69 61 62 | interger variab| 00000b20 6c 65 2e 20 0d 41 20 76 61 72 69 61 62 6c 65 20 |le. .A variable | 00000b30 77 69 74 68 6f 75 74 20 61 20 10 73 69 67 6e 20 |without a .sign | 00000b40 69 73 20 63 61 6c 6c 65 64 20 61 20 72 65 61 6c |is called a real| 00000b50 20 76 61 72 69 61 62 6c 65 20 61 6e 64 20 0d 63 | variable and .c| 00000b60 61 6e 20 62 65 20 75 73 65 64 20 66 6f 72 20 77 |an be used for w| 00000b70 68 6f 6c 65 20 10 6e 75 6d 62 65 72 73 20 61 6e |hole .numbers an| 00000b80 64 20 66 72 61 63 74 69 6f 6e 73 2e 20 0d 49 20 |d fractions. .I | 00000b90 75 73 65 64 20 72 65 61 6c 20 76 61 72 69 61 62 |used real variab| 00000ba0 6c 65 73 20 73 69 6d 70 6c 79 20 74 6f 20 10 73 |les simply to .s| 00000bb0 61 76 65 20 73 6f 6d 65 20 74 69 6d 65 20 74 79 |ave some time ty| 00000bc0 70 69 6e 67 20 62 75 74 20 0d 73 6f 6d 65 74 69 |ping but .someti| 00000bd0 6d 65 73 20 69 74 20 69 73 20 6e 65 63 65 73 73 |mes it is necess| 00000be0 61 72 79 20 74 6f 20 75 73 65 20 10 61 6e 20 69 |ary to use .an i| 00000bf0 6e 74 65 67 65 72 20 76 61 72 69 61 62 6c 65 20 |nteger variable | 00000c00 66 6f 72 20 0d 65 78 61 6d 70 6c 65 20 77 68 65 |for .example whe| 00000c10 6e 20 74 68 65 20 63 6f 75 6e 74 69 6e 67 20 69 |n the counting i| 00000c20 6e 20 74 68 65 20 10 46 4f 52 20 4e 45 58 54 20 |n the .FOR NEXT | 00000c30 6c 6f 6f 70 20 6d 69 67 68 74 20 0d 70 72 6f 64 |loop might .prod| 00000c40 75 63 65 20 61 20 66 72 61 63 74 69 6f 6e 20 77 |uce a fraction w| 00000c50 68 69 63 68 20 79 6f 75 20 77 61 6e 74 20 74 68 |hich you want th| 00000c60 65 20 10 63 6f 6d 70 75 74 65 72 20 74 6f 20 69 |e .computer to i| 00000c70 67 6e 6f 72 65 2e 20 0d 54 68 65 20 66 69 72 73 |gnore. .The firs| 00000c80 74 20 44 41 54 41 20 73 74 61 74 65 6d 65 6e 74 |t DATA statement| 00000c90 20 69 73 20 72 65 61 64 20 6f 6e 20 10 74 68 65 | is read on .the| 00000ca0 20 66 69 72 73 74 20 70 61 73 73 20 6f 66 20 74 | first pass of t| 00000cb0 68 65 20 0d 6c 6f 6f 70 2c 20 6f 6e 20 74 68 65 |he .loop, on the| 00000cc0 20 73 65 63 6f 6e 64 20 70 61 73 73 20 74 68 65 | second pass the| 00000cd0 20 73 65 63 6f 6e 64 20 10 44 41 54 41 20 73 74 | second .DATA st| 00000ce0 61 74 65 6d 65 6e 74 20 69 73 20 72 65 61 64 20 |atement is read | 00000cf0 0d 61 6e 20 73 6f 20 6f 6e 2e 0d 0d 31 30 30 50 |.an so on...100P| 00000d00 52 49 4e 54 54 41 42 28 31 2c 31 32 29 41 24 20 |RINTTAB(1,12)A$ | 00000d10 54 68 69 73 20 73 69 6d 70 6c 79 20 74 65 6c 6c |This simply tell| 00000d20 73 20 74 68 65 20 63 6f 6d 70 75 74 65 72 20 74 |s the computer t| 00000d30 6f 20 70 72 69 6e 74 20 0d 41 24 20 77 68 61 74 |o print .A$ what| 00000d40 65 76 65 72 20 69 74 20 68 61 70 70 65 6e 73 20 |ever it happens | 00000d50 74 6f 20 62 65 20 61 74 20 74 68 61 74 20 74 69 |to be at that ti| 00000d60 6d 65 20 69 6e 20 61 20 70 61 72 74 69 63 75 6c |me in a particul| 00000d70 61 72 20 0d 70 6f 73 69 74 69 6f 6e 2e 0d 0d 31 |ar .position...1| 00000d80 31 30 50 52 49 4e 54 54 41 42 28 31 2c 31 39 29 |10PRINTTAB(1,19)| 00000d90 22 20 54 68 69 73 20 6c 69 6e 65 20 77 6f 75 6c |" This line woul| 00000da0 64 20 6f 66 66 65 6e 64 20 6d 6f 73 74 20 42 41 |d offend most BA| 00000db0 53 49 43 20 0d 70 72 6f 67 72 61 6d 6d 65 72 73 |SIC .programmers| 00000dc0 2e 20 49 74 20 70 72 69 6e 74 73 20 61 20 62 6c |. It prints a bl| 00000dd0 61 6e 6b 20 6c 69 6e 65 20 69 6e 20 61 20 70 61 |ank line in a pa| 00000de0 72 74 69 63 75 6c 61 72 20 70 6f 73 69 74 69 6f |rticular positio| 00000df0 6e 20 0d 77 68 69 63 68 20 10 69 73 20 10 75 73 |n .which .is .us| 00000e00 65 64 20 10 66 75 72 74 68 65 72 20 10 64 6f 77 |ed .further .dow| 00000e10 6e 20 10 74 68 65 20 10 70 72 6f 67 72 61 6d 2e |n .the .program.| 00000e20 20 10 53 6f 20 10 77 68 65 6e 20 74 68 69 73 20 | .So .when this | 00000e30 0d 70 6f 73 69 74 69 6f 6e 20 68 61 73 20 73 6f |.position has so| 00000e40 6d 65 74 68 69 6e 67 20 77 72 69 74 74 65 6e 20 |mething written | 00000e50 6f 6e 74 6f 20 69 74 20 6c 61 74 65 72 20 6f 6e |onto it later on| 00000e60 20 69 6e 20 74 68 65 20 0d 70 72 6f 67 72 61 6d | in the .program| 00000e70 2c 20 74 68 65 20 6c 6f 6f 70 20 63 79 63 6c 65 |, the loop cycle| 00000e80 73 20 61 72 6f 75 6e 64 20 61 6e 64 20 65 78 65 |s around and exe| 00000e90 63 75 74 65 73 20 74 68 69 73 20 6c 69 6e 65 20 |cutes this line | 00000ea0 61 67 61 69 6e 0d 61 6e 64 20 74 68 69 73 20 6c |again.and this l| 00000eb0 69 6e 65 20 65 66 66 65 63 74 69 76 6c 79 20 65 |ine effectivly e| 00000ec0 72 61 73 65 73 20 74 68 69 73 20 70 6f 73 69 74 |rases this posit| 00000ed0 69 6f 6e 2e 0d 54 68 65 72 65 20 61 72 65 20 6d |ion..There are m| 00000ee0 6f 72 65 20 65 6c 65 67 61 6e 74 20 77 61 79 73 |ore elegant ways| 00000ef0 20 6f 66 20 64 6f 69 6e 67 20 10 74 68 69 73 20 | of doing .this | 00000f00 62 75 74 20 74 68 69 73 20 77 6f 72 6b 73 20 0d |but this works .| 00000f10 71 75 69 74 65 20 77 65 6c 6c 20 61 6e 64 2e 2e |quite well and..| 00000f20 2e 2e 2e 0d 0d 31 32 30 46 4f 52 54 25 3d 31 20 |.....120FORT%=1 | 00000f30 54 4f 20 42 25 20 54 68 69 73 20 69 73 20 61 6e |TO B% This is an| 00000f40 6f 74 68 65 72 20 46 4f 52 20 4e 45 58 54 20 6c |other FOR NEXT l| 00000f50 6f 6f 70 2e 20 54 68 69 73 20 74 69 6d 65 20 0d |oop. This time .| 00000f60 69 74 73 20 70 75 72 70 6f 73 65 20 69 73 20 73 |its purpose is s| 00000f70 69 6d 70 6c 79 20 74 6f 20 6d 61 6b 65 20 74 68 |imply to make th| 00000f80 65 20 63 6f 6d 70 75 74 65 72 20 77 61 69 74 20 |e computer wait | 00000f90 66 6f 72 20 61 20 77 68 69 6c 65 20 0d 62 65 66 |for a while .bef| 00000fa0 6f 72 65 20 65 78 65 63 75 74 69 6e 67 20 74 68 |ore executing th| 00000fb0 65 20 6e 65 78 74 20 69 6e 73 74 72 75 63 74 69 |e next instructi| 00000fc0 6f 6e 20 62 65 63 61 75 73 65 20 69 74 20 68 61 |on because it ha| 00000fd0 73 20 74 6f 20 0d 63 6f 75 6e 74 20 75 70 20 74 |s to .count up t| 00000fe0 6f 20 31 30 30 30 30 20 77 68 69 63 68 20 69 73 |o 10000 which is| 00000ff0 20 77 68 61 74 20 42 25 20 69 73 20 65 71 75 61 | what B% is equa| 00001000 6c 20 74 6f 2e 20 49 6e 20 74 68 69 73 20 0d 63 |l to. In this .c| 00001010 61 73 65 20 69 74 73 20 70 75 72 70 6f 73 65 20 |ase its purpose | 00001020 69 73 20 74 6f 20 6d 61 6b 65 20 73 6f 6d 65 20 |is to make some | 00001030 74 69 6d 65 20 74 6f 20 72 65 61 64 20 41 24 20 |time to read A$ | 00001040 66 72 6f 6d 20 6c 69 6e 65 20 0d 31 30 30 2e 20 |from line .100. | 00001050 41 67 61 69 6e 20 10 74 68 65 72 65 20 61 72 65 |Again .there are| 00001060 20 6d 6f 72 65 20 65 6c 65 67 61 6e 74 20 77 61 | more elegant wa| 00001070 79 73 20 74 6f 20 64 6f 20 74 68 69 73 20 62 75 |ys to do this bu| 00001080 74 2e 2e 2e 2e 0d 0d 54 68 65 20 76 61 72 69 61 |t......The varia| 00001090 62 6c 65 20 42 25 20 69 73 20 75 73 65 64 20 62 |ble B% is used b| 000010a0 65 63 61 75 73 65 20 77 68 65 6e 20 49 20 77 61 |ecause when I wa| 000010b0 73 20 64 65 76 65 6c 6f 70 69 6e 67 20 74 68 65 |s developing the| 000010c0 20 0d 70 72 6f 67 72 61 6d 20 49 20 77 61 6e 74 | .program I want| 000010d0 65 64 20 74 6f 20 6d 61 6b 65 20 69 74 20 72 75 |ed to make it ru| 000010e0 6e 20 71 75 69 74 65 20 66 61 73 74 2e 20 49 20 |n quite fast. I | 000010f0 64 69 64 6e 27 74 20 6e 65 65 64 20 74 6f 20 0d |didn't need to .| 00001100 72 65 61 64 20 41 24 20 73 69 6e 63 65 20 49 20 |read A$ since I | 00001110 68 61 64 20 77 72 69 74 74 65 6e 20 41 24 2e 20 |had written A$. | 00001120 44 75 72 69 6e 67 20 64 65 76 65 6c 6f 70 6d 65 |During developme| 00001130 6e 74 20 49 20 77 61 73 20 0d 73 65 74 74 69 6e |nt I was .settin| 00001140 67 20 42 25 20 74 6f 20 31 30 30 2e 54 68 69 73 |g B% to 100.This| 00001150 20 74 72 69 63 6b 20 69 73 20 75 73 65 64 20 61 | trick is used a| 00001160 67 61 69 6e 20 10 6c 61 74 65 72 20 6f 6e 20 73 |gain .later on s| 00001170 6f 20 0d 74 68 61 74 20 64 65 6c 61 79 73 20 61 |o .that delays a| 00001180 72 65 20 61 6c 6c 20 6f 66 20 74 68 65 20 73 61 |re all of the sa| 00001190 6d 65 20 6c 65 6e 67 74 68 2e 0d 0d 31 33 30 4e |me length...130N| 000011a0 45 58 54 54 25 20 53 65 65 20 61 62 6f 76 65 2e |EXTT% See above.| 000011b0 0d 0d 31 34 30 52 45 41 44 20 42 24 20 54 68 69 |..140READ B$ Thi| 000011c0 73 20 69 73 20 65 78 61 63 74 6c 79 20 74 68 65 |s is exactly the| 000011d0 20 73 61 6d 65 20 61 73 20 74 68 65 20 52 45 41 | same as the REA| 000011e0 44 20 41 24 2e 20 42 75 74 20 69 6e 20 0d 74 68 |D A$. But in .th| 000011f0 69 73 20 63 61 73 65 20 69 74 20 77 69 6c 6c 20 |is case it will | 00001200 62 65 20 74 68 65 20 6e 65 78 74 20 44 41 54 41 |be the next DATA| 00001210 20 73 74 61 74 65 6d 65 6e 74 20 64 6f 77 6e 2e | statement down.| 00001220 0d 0d 31 35 30 50 52 49 4e 54 54 41 42 28 31 2c |..150PRINTTAB(1,| 00001230 31 39 29 42 24 20 41 67 61 69 6e 20 74 68 65 20 |19)B$ Again the | 00001240 73 61 6d 65 20 61 73 20 6c 69 6e 65 20 31 30 30 |same as line 100| 00001250 20 62 75 74 20 6e 6f 74 69 63 65 20 0d 74 68 61 | but notice .tha| 00001260 74 20 74 68 65 20 70 6f 73 69 74 69 6f 6e 20 66 |t the position f| 00001270 6f 72 20 70 72 69 6e 74 69 6e 67 20 69 73 20 64 |or printing is d| 00001280 69 66 66 65 72 65 6e 74 2e 0d 0d 31 36 30 50 52 |ifferent...160PR| 00001290 49 4e 54 54 41 42 28 31 2c 31 32 29 22 20 54 68 |INTTAB(1,12)" Th| 000012a0 69 73 20 70 75 74 73 20 61 20 62 6c 61 6e 6b 20 |is puts a blank | 000012b0 6c 69 6e 65 20 69 6e 20 74 68 65 20 70 6f 73 69 |line in the posi| 000012c0 74 69 6f 6e 20 0d 77 68 65 72 65 20 41 24 20 77 |tion .where A$ w| 000012d0 61 73 20 70 72 69 6e 74 65 64 2e 20 41 24 20 69 |as printed. A$ i| 000012e0 73 20 65 72 61 73 65 64 20 61 6e 64 20 73 6f 20 |s erased and so | 000012f0 42 24 20 6c 6f 6f 6b 73 20 6c 69 6b 65 20 61 20 |B$ looks like a | 00001300 0d 72 65 70 6c 79 20 74 6f 20 41 24 2e 0d 0d 31 |.reply to A$...1| 00001310 37 30 46 4f 52 54 25 3d 31 20 54 4f 20 42 25 0d |70FORT%=1 TO B%.| 00001320 31 38 30 4e 45 58 54 54 25 20 20 20 20 20 20 20 |180NEXTT% | 00001330 20 54 68 69 73 20 69 73 20 61 6e 20 69 64 65 6e | This is an iden| 00001340 74 69 63 61 6c 20 64 65 6c 61 79 20 74 6f 20 6c |tical delay to l| 00001350 69 6e 65 73 20 31 32 30 20 0d 61 6e 64 20 31 33 |ines 120 .and 13| 00001360 30 0d 0d 31 39 30 4e 45 58 54 20 41 20 54 68 69 |0..190NEXT A Thi| 00001370 73 20 69 73 20 74 68 65 20 65 6e 64 20 6f 66 20 |s is the end of | 00001380 74 68 65 20 6f 72 69 67 69 6e 61 6c 20 46 4f 52 |the original FOR| 00001390 20 4e 45 58 54 20 6c 6f 6f 70 2e 20 74 68 65 20 | NEXT loop. the | 000013a0 0d 63 6f 6d 70 75 74 65 72 20 77 69 6c 6c 20 61 |.computer will a| 000013b0 64 64 20 6f 6e 65 20 74 6f 20 41 20 61 6e 64 20 |dd one to A and | 000013c0 74 68 65 6e 20 67 6f 20 62 61 63 6b 20 74 6f 20 |then go back to | 000013d0 6c 69 6e 65 20 38 30 20 74 6f 20 0d 6c 6f 6f 70 |line 80 to .loop| 000013e0 20 74 68 72 6f 75 67 68 20 74 68 65 20 69 6e 73 | through the ins| 000013f0 74 72 75 63 74 69 6f 6e 73 20 61 67 61 69 6e 20 |tructions again | 00001400 75 6e 74 69 6c 20 6f 66 20 63 6f 75 72 73 65 20 |until of course | 00001410 41 20 3d 20 38 0d |A = 8.| 00001416
F/Scren1.m0
F/Scren1.m1
F/Scren1.m2
F/Scren1.m4
F/Scren1.m5
.