MMDEBUG CLS
MMDEBUG IF a=5 THEN PRINT

CONST MAX.DBG = 20            'maximal number of watched vaiables
DIM STRING DBG.DBG(MAX.DBG)   'DEBUG watchlist
DIM INTEGER LEN.DBG = -1      'current number of watched variables
DIM INTEGER ON.DBG = 0        'DEBUG ON or OFF
DIM INTEGER PERIOD.DBG = 1000 'output period in ms
DIM INTEGER X.DBG=0, Y.DBG=0  'screen coordinates for output

'*** SUBs and FUNCTIONs ***
'DBGon(period, x, y)  switch DEBUG ON and set output to every period in ms at @(x,y)
'DBGoff               switch DEBUG OFF
'DBGout               print DEBUG informations
'DBGadd(variable)     add var to watchlist, string var have to end with $
'                     INTEGER/FLOAT var can be prefixed with &N for HEX output with N digits                      
'DBGdel(variable)     remove var from watchlist
'
SUB DBGon(period AS INTEGER, x AS INTEGER, y AS INTEGER)
 ON.DBG = 1
 IF period = 0 THEN period = 1000
 X.DBG = x:Y.DBG = y
 DBGout
 SETTICK period, DBGout, 4
END SUB

SUB DBGoff
 ON.DBG = 0
 SETTICK 0,0,4
END SUB

FUNCTION DBGfind(elm AS STRING) AS INTEGER
 LOCAL INTEGER i, f = -1
 FOR i = 0 TO LEN.DBG
   IF LCASE$(elm) = LCASE$(DBG.DBG(i)) THEN
     f = i
     EXIT FOR
   ENDIF
 NEXT i
 DBGfind = f
END FUNCTION

SUB DBGout
 LOCAL INTEGER i, h =MM.INFO(FONTHEIGHT)
 LOCAL STRING s, q = CHR$(34)

 FOR i = 0 TO LEN.DBG
   IF INSTR(DBG.DBG(i),"$") = 0 THEN
     IF LEFT$(DBG.DBG(i),1)="&" THEN
       's="HEX$("+MID$(DBG.DBG(i),3)+"," + MID$(DBG.DBG(i),2,1)+")"
       '?s:ERROR"STOP"
       s = MID$(DBG.DBG(i),3) + "=" + EVAL("HEX$("+MID$(DBG.DBG(i),3)+"," + MID$(DBG.DBG(i),2,1)+")")+"   "
     ELSE
       s = DBG.DBG(i) + "=" + EVAL("STR$("+DBG.DBG(i)+")   ")
     ENDIF
   ELSE
     s = DBG.DBG(i) + "=" + q + EVAL(DBG.DBG(i)) + q+ "   "
   ENDIF
   TEXT X.DBG, Y.DBG + i*h, s
 NEXT i
END SUB

SUB DBGdel(elm AS STRING)
 LOCAL INTEGER i, f = DBGfind(elm)

 IF f <> -1 THEN
   IF f < LEN.DBG THEN
     FOR i = f TO LEN.DBG
       DBG.DBG(i) = DBG.DBG(i+1)
     NEXT i
   ENDIF
   LEN.DBG = LEN.DBG - 1      
 ENDIF
END SUB

SUB DBGadd(elm AS STRING)
 IF DBGfind(elm) = -1 THEN
   IF LEN.DBG < MAX.DBG THEN
     LEN.DBG = LEN.DBG + 1
     DBG.DBG(LEN.DBG) = elm
   ENDIF
 ENDIF
END SUB

MMDEBUG CLS
MMDEBUG TEXT...
MMDEBUG IF a = 5 THEN PRINT something
...