add example basic program

md/Atari/entries/various-atari-basic.md

@@ -8,4 +8,70 @@ I have a love-hate relationship with BASIC. It's easy to get started, it's diffi
 
 ---
 
-* [Display The ATASCII Character Set](charset.md)
+**Display the ATASCII character set**
+
+<pre class="atari">
+10 GRAPHICS 0
+15 DIM CHAR$(10)
+20 FOR I=0 TO 252
+21 IF I=125 THEN CHAR$="[CLEAR]":GOTO 45
+22 IF I=155 THEN CHAR$="[RETURN]":GOTO 45
+23 IF I=29 THEN CHAR$="[UNPRINTABLE]":GOTO 45
+35 CHAR$=CHR$(I)
+45 PRINT I;" ";CHR$(27);" ";CHAR$
+50 NEXT I
+60 REM USE CONTROL-1 TO PAUSE
+</pre>
+
+**Variable Name Introspection**
+
+<pre class="atari">
+100 REM PROGRAM TO PRINT THE VARIABLE NAME LIST 
+105 PRINT "Before line 110"
+110 DIM ARRAYNAME(1),STRINGNAME$(1)
+120 REM GET THE BEGINNING OF THE LIST 
+125 PRINT "Before line 130"
+130 ADDRESS=PEEK(130)+PEEK(131)*256
+135 PRINT "Before line 140: ";ADDRESS
+140 ? CHR$(125);"VARIABLE NAME LIST"
+150 REM GET CHARACTER AND TEST FOR END 
+155 PRINT "Before line 160"
+160 A=PEEK(ADDRESS):IF A=0 THEN END 
+165 PRINT "Before line 180: ";A
+170 REM PRINT CHARACTER 
+180 IF A<128 THEN ? CHR$(A);:REM 210
+190 ? CHR$(A-128)
+200 REM GET NEXT ADDRESS AND REPEAT 
+210 ADDRESS=ADDRESS+1:REM 160
+</pre>
+
+**The MYMORT1 Program from DTSS**
+
+<pre class="atari">
+1   REM  MORTGAGE COMOPUTER
+2   REM  YEARLY INTEREST RATE
+10  DATA  0.05
+15  REM  INITIAL PRINCIPAL
+20  DATA  28500
+25  REM  MONTHLY PAYMENT
+30  DATA  170
+35  REM  STARTING MONTH AND YEAR
+40  DATA  1, 1964
+50  READ I, P, P1, M, Y
+60  LET R = 1 + I/12
+70  PRINT "YEAR", "PRINCIPAL"
+80  PRINT Y, P
+90  LET  P = P*R - P1
+100 IF  P >= 0 THEN 120
+110 LET P = 0
+120 LET M = M + 1
+130  IF M > 12 THEN 160
+140  PRINT "       ",
+150  GO TO 190
+160  LET  M = 1
+170  LET Y = Y + 1
+180  PRINT Y,
+190  PRINT INT(P)
+200  IF P > 0 THEN 90
+210  END
+</pre>