CLS : PRINT "Magnetic Field Mapper, Copyright 1999 By Robert J Davis"
PRINT "Output readings are in milligauss use maximum-minimum / 2"
INPUT "Use Printer Port Nunber: ", LPT
dout = &H378: cout = &H37A: cin = &H379
IF LPT = 1 THEN dout = &H3BC: cout = &H3BE: cin = &H3BD
IF LPT = 3 THEN dout = &H278: cout = &H27A: cin = &H279
mhour$ = MID$(TIME$, 1, 2)
DIM mfield(99)

start:
hour$ = MID$(TIME$, 1, 2)
IF hour$ = mhour$ AND cycle = 1 THEN GOTO start
cycle = cycle + 1
IF cycle > 2 THEN cycle = 0
mhour$ = hour$

max1 = -999: max2 = -999 'use for negative numbers
max3 = -999: max4 = -999 'use for negative numbers
min1 = 0: min2 = 0: min3 = 0: min4 = 0
waittime = 42       '486 - 25 speed
Findstop:
OUT cout, 0
FOR b = 0 TO 3
  OUT dout, 2 ^ b
  IF (INP(cin) \ 16) MOD 2 = 1 THEN GOTO getforward
  FOR A = 1 TO waittime: NEXT A
NEXT b
GOTO Findstop

getforward:
FOR c = 1 TO 16

getinput1:
OUT cout, 8
OUT cout, 3: value1 = (INP(cin) XOR &H80) \ 16
OUT cout, 2: value2 = (INP(cin) XOR &H80) \ 16
OUT cout, 1: value3 = (INP(cin) XOR &H80) \ 16
tvalue1 = value1 + (16 * value2) + (256 * value3)
IF tvalue1 > 2048 THEN tvalue1 = tvalue1 - 4096
LOCATE c + 3, 1: PRINT tvalue1
IF max1 < tvalue1 THEN max1 = tvalue1
IF min1 > tvalue1 THEN min1 = tvalue1
mfield(c) = tvalue1

getinput3:
OUT cout, 8
OUT cout, 3: value1 = (INP(cin) XOR &H80) \ 16
OUT cout, 2: value2 = (INP(cin) XOR &H80) \ 16
OUT cout, 1: value3 = (INP(cin) XOR &H80) \ 16
tvalue3 = value1 + (16 * value2) + (256 * value3)
IF tvalue3 > 2048 THEN tvalue3 = tvalue3 - 4096
LOCATE c + 3, 20: PRINT tvalue3
IF max3 < tvalue3 THEN max3 = tvalue3
IF min3 > tvalue3 THEN min3 = tvalue3
mfield(c + 40) = tvalue3

counterclockwise:
FOR d = 1 TO 3
  FOR b = 3 TO 0 STEP -1
   OUT dout, 2 ^ b
   FOR A = 1 TO waittime: NEXT A
  NEXT b
NEXT d
NEXT c

getreverse:
FOR c = 1 TO 16

clockwise:
FOR d = 1 TO 3
  FOR b = 0 TO 3
   OUT dout, 2 ^ b
   FOR A = 1 TO waittime: NEXT A
  NEXT b
NEXT d

getinput2:
OUT cout, 8
OUT cout, 3: value1 = (INP(cin) XOR &H80) \ 16
OUT cout, 2: value2 = (INP(cin) XOR &H80) \ 16
OUT cout, 1: value3 = (INP(cin) XOR &H80) \ 16
tvalue2 = value1 + (16 * value2) + (256 * value3)
IF tvalue2 > 2048 THEN tvalue2 = tvalue2 - 4096
LOCATE 20 - c, 10: PRINT tvalue2
IF max2 < tvalue2 THEN max2 = tvalue2
IF min2 > tvalue2 THEN min2 = tvalue2
mfield(c + 20) = tvalue2

getinput4:
OUT cout, 8
OUT cout, 3: value1 = (INP(cin) XOR &H80) \ 16
OUT cout, 2: value2 = (INP(cin) XOR &H80) \ 16
OUT cout, 1: value3 = (INP(cin) XOR &H80) \ 16
tvalue4 = value1 + (16 * value2) + (256 * value3)
IF tvalue4 > 2048 THEN tvalue4 = tvalue4 - 4096
LOCATE 20 - c, 30: PRINT tvalue4
IF max4 < tvalue4 THEN max4 = tvalue4
IF min4 > tvalue4 THEN min4 = tvalue4
mfield(c + 60) = tvalue4
NEXT c

Park:
FOR d = 1 TO 27
  FOR b = 3 TO 0 STEP -1
   OUT dout, 2 ^ b
   FOR A = 1 TO waittime: NEXT A
  NEXT b
NEXT d
OUT dout, 0  'shut off stepper

display:
LOCATE 9, 40: PRINT "Scan1 Scan2 Scan3 Scan4 Average"
LOCATE 10, 40: PRINT max1 - min1
LOCATE 10, 46: PRINT max2 - min2
LOCATE 10, 52: PRINT max3 - min3
LOCATE 10, 58: PRINT max4 - min4
LOCATE 10, 64: PRINT (max1 - min1 + max2 - min2 + max3 - min3 + 
   max4 - min4)
/ 4
Save:
mfile$ = "c:" + MID$(DATE$, 7, 4) + MID$(DATE$, 1, 2) + MID$(DATE$, 
   4, 2)
OPEN mfile$ FOR APPEND AS #1
FOR c = 1 TO 16
PRINT #1, mfield(c);
NEXT c
PRINT #1, " "
FOR c = 21 TO 36
PRINT #1, mfield(c);
NEXT c
PRINT #1, " "
FOR c = 41 TO 56
PRINT #1, mfield(c);
NEXT c
PRINT #1, " "
FOR c = 61 TO 76
PRINT #1, mfield(c);
NEXT c
PRINT #1, " "
PRINT #1, "Range", max1 - min1, max2 - min2, max3 - min3, max4 - 
   min4
PRINT #1, TIME$
CLOSE #1

GOTO start
END