10 LET yos=0
   20 LET c$=STRING$(100,"~")
   30 LET ad=LENGTH(0,c$)
   40 LOAD "modes.c"CODE ad
   50 REM  **** PRESS SPACE to exit from MC ****
   60 REM Store code in a string (c$) to prevent program or variables from overw
      riting it
   70  
   80 MODE 4: CLS #: LET xrg=256
   90 POKE ad+7,0: REM  (ad+7) normally = 243, ie, disable interrupts, but this 
      means that palette line changes will also be disabled. Too many palette li
      ne changes, or key presses, may disrupt the routine.
  100  
  110 CSIZE 8,8
  120 LET yos=0
  130 LOAD "modes.$"SCREEN$
  140 PALETTE 2,14
  150 PALETTE 2,14 LINE 50 : PALETTE 3, 112 LINE 50
  160 FOR n=-16 TO 52: PLOT 0,n: DRAW PEN n MOD 16;255,0: NEXT n
  170 PRINT #1; AT 0,10; "Press SPACE"
  180 POKE ad+1,192-69: REM bottom of mode 3 section
  190 POKE ad+3,192-152: REM top of mode 3 section
  200  
  210 REM  Note that 0 is at the top of the screen
  220  
  230 FOR n=1 TO 5
  240 CALL ad
  250 PALETTE 3,RND(127)
  260 PALETTE 2,RND(127)
  270 POW 
  280 NEXT n
  290 MODE 4: CLS #
  300 LOAD "mandelA.$"SCREEN$
  310 PRINT #0; AT 0,0; PAPER 0; PEN 15;"Press SPACE"
  320 PALETTE 3,127 LINE -1
  330 PUT 0,-10,a$
  340 FOR n=1 TO 8
  350 POKE ad+1,192-RND(175)
  360 POKE ad+3,192-RND(175)
  370 POW 
  380 CALL ad
  390 NEXT n
  400 MODE 3: CLS #: 
  410 RESTORE 440 : FOR n=0 TO 15: READ a: PALETTE n,a LINE 70: NEXT n
  420 RESTORE 430: FOR n=0 TO 15: READ a: PALETTE n,a LINE 18: NEXT n
  430 DATA 0,0,1,9,16,17,19,25,27,23,29,81,83,89,85,93
  440 DATA 0,40,32,1,64,72,2,99,9,17,27,31,61,39,4,119
  450 POKE SVAR 64,3
  460 LET yos=0,xrg=256
  470 FOR n=0 TO 255 STEP 32: FOR m=0 TO 15: PEN m: PLOT n+m,-16: DRAW 0,16: NEX
      T m: FOR m=16 TO 31: PEN 32-m: PLOT n+m,-16: DRAW 0,16: NEXT m: NEXT n
  480 PUT 0,70,e1$: PUT 128,70,e2$
  490 POKE SVAR 64,2
  500 PAPER 0: PEN 3
  510 CSIZE 8,8: PUT 0,175,b$
  520 WINDOW 0,63,4,11
  530 PRINT "This MODESWITCHER lets you switch mode anywhere in a screen - sotha
      t you can have areas of graphics and 80 column text on screenat once."
  540 PRINT '"The code is fully relocatable, and can be placed in addresses   32
      768-65535 - unlike, eg, SHRINKER. POKE (ad+1) with the bottom of the area 
      to be in MODE 3 (0 is at the top: 191 is at the     bottom), and (ad+3) wi
      th the top of this area.     Press <SPACE>"
  550 LET ad=LENGTH(0,c$)
  560 POKE ad+1,192-82: POKE ad+3,192-165:
  570 FOR n=80 TO 165 STEP 8: PALETTE 3,(n/10)+80 LINE n: NEXT n
  580 CALL ad
  590 PRINT AT 0,0;"Normally, (ad+7)=243, which disables interrupts, so that the
          edges of the mode sections are straight. However, if you want toset up
       palette areas, using the LINE function, you will have to POKE (ad+7) with
       0. "
  600 PRINT  "         This routine uses the HPEN and LPEN I/O ports to time  th
      e mode switching correctly, but by using a simple program suchas that give
      n at the end of the listing, you can create    ": PRINT "different effects
      .                            "
  610 CALL ad
  611 FOR n=80 TO 165 STEP 8: PALETTE 3 LINE n: NEXT n
  612 CSIZE 6,8
  613 WINDOW 0,84,4,11: POKE SVAR 0,"~": POKE UDG "~",255,255,255,255,255,255,25
      5,255
  614 CLS 1: LET m=10: SCROLL CLEAR 
  620 LIST m TO m+50
  635 CALL ad
  640 CLS 1: LET m=m+50: IF m>700 THEN GO TO 700
  650 GO TO 615
  700 MODE 3: CLS #: CSIZE 8,8:
  705 PRINT "NOW HAVE A LOOK AT THE LISTING": POKE SVAR 0,">"
  706 ZAP : REM   ****   PRESS SPACE!  ****
  710  
  711 REM      **** PRESS SPACE ****
 1000 REM        IN A,(252)        ;get video page
 1010  
 1020 REM ; port 252 gives:
 1030 REM  ;BIT7  BIT6  BIT5  BIT4  BIT3   BIT2  BIT1  BIT0
 1040 REM ;midi  mode1  mode0  bank page8  page4 page2 page1
 1050 REM ; We want to change BIT 5 and BIT 6
 1051  
 1060 REM        SET 5,A  
 1070 REM  LOOP: SET 6,A
 1080 REM        OUT (252),A       ; this gives mode4
 1090 REM        RES 6,A
 1100 REM        OUT (252),A       ; this give mode3
 1110 REM        JR LOOP           ; repeat
 1111  
 1120 REM Obviously some kind of delay  is needed is needed     before each loop
       to slow the loop down.