10 REM > F7_fax
   20 :
   30 REM Teletext core program
   40 :
   50 REM By Andrew J Nibbs
   60 REM (c) Swig soft 1990
   70 :
   80 ON ERROR OSCLI("DRIVE 0"):CHAIN"!Menu"
   90 MODE7
  100 VDU23;8202;0;0;0;
  110 HIMEM=&7000-1000
  120 FORx=HIMEM TO &7000 STEP 4:!x=0:NEXT
  130 DIM e(2)
  140 frame=97
  150 mf=123
  160 page$="010"
  170 PROCass
  180 :
  190 PROCloadpage
  200 silly$=page$
  210 PROCtopline
  220 TIME=0
  230 new_page=FALSE
  240 REPEAT
  250 *FX15
  260 x=GET
  270 IF x=32:TIME=1000  
  280 PROCnext_frame
  290 IFnotload:GOTO220
  300 GOTO190
  310 :
  320 DEFPROCass:FORB%=0TO2STEP2:P%=&A00:[OPTB%:.rep LDA#&7C:STA&81:LDA#0:STA&80:LDX#4
  330 .loop1 LDY#0:.loop2 LDA s:CMP(&80),Y:BEQ fs:.cafs INY:BNE loop2:INC&81:DEX:CPX#0:BNE loop1:RTS:.fs LDA r:STA(&80),Y:JMPcafs:.r NOP:.s NOP
  340 .load80 LDA#0:STA&82:LDA#&7C:STA&83
  350 .outer2 LDY#0:.inner2 LDA(&80),Y:STA(&82),Y:INY
  360 BNE inner2:INC&83:INC&81:LDA &83:CMP#&80:BNE outer2:RTS
  370 .dtop LDX#0:LDA#32:.dtl STA &7000,X:INX:CPX#40:BNE dtl:RTS
  380 ]:NEXT:ENDPROC
  390 :
  400 DEFPROCreveal
  410 ?s=152:?r=142:CALLrep
  420 REPEATUNTILNOT(INKEY(-52))
  430 ?s=142:?r=152:CALLrep
  440 ENDPROC
  450 :
  460 DEFPROCnext_frame
  470 frame=frame+1
  480 IFframe=mf frame=97
  490 answer=FNnoex(page$+CHR$frame)
  500 IF answer AND frame=98:notload=TRUE:ELSE:notload=FALSE
  510 IF answer frame=97
  520 ENDPROC
  530 :
  540 DEFPROCxtopage
  550 notload=FALSE
  560 frame=97
  570 op$=page$
  580 page$=CHR$e(0)
  590 page$=page$+CHR$e(1)
  600 page$=page$+CHR$e(2)
  610 IF FNnoex(page$+CHR$frame):page$=op$:notload=TRUE
  620 ENDPROC
  630 :
  640 DEFPROCloadpage
  650 OSCLI"LOAD "+page$+CHR$frame+" 7000"
  660 CALLdtop
  670 FORattledog=&7000-1000 TO &7000 STEP 40:?&80=attledog MOD 256:?&81=attledog DIV 256:*FX19
  680 CALLload80:NEXT
  690 ENDPROC
  700 :
  710 DEFPROCtopline
  720 VDU30
  730 PRINTTAB(30)"…";page$ CHR$frame
  740 ENDPROC
  750 :
  760 DEF FNinput
  770 ent=FALSE
  780 PRINTTAB(0,0)"ƒ..."
  790 digit=0
  800 IF INKEY(-85):=20000
  810 IF INKEY(-86):=30000
  820 IF INKEY(-52):=10000
  830 x=INKEY(0)
  840 IFx<47 OR x>58:=99999
  850 ent=TRUE
  860 GOTO890
  870 x=GET
  880 IFx<47 OR x>58:=99999
  890 digit?&7C01=x
  900 e(digit)=x
  910 digit=digit+1
  920 IFdigit=3 GOTO940
  930 GOTO870
  940 =0
  950 :
  960 DEF FNnoex(x$)
  970 y=OPENUP x$:CLOSE#y
  980 IFy=0:=TRUE
  990 =FALSE