'Data to P0
'Clock to P1
Pause 100

dat VAR Byte
YY var byte
XX var byte
xx = 0
SQUAL VAR BYTE
Totalx var sword
Totalx = 0
Totaly var sword
Totaly = 0

'------------------------------
'x-y
'-----------------------------

loop:
output P0
shiftout P0,P1,0,[2\8]
Pause 1
shiftin P0,P1,0,[dat\8]
YY=dat
If yy < 127 then
totaly= totaly + yy
else
yy= yy ^ 255 + 1
Totaly = Totaly - yy
endif

output P0
shiftout P0,P1,0,[3\8]
Pause 1
shiftin P0,P1,0,[dat\8]
XX=dat

If xx < 127 then
totalx= totalx + xx
else
xx= xx ^ 255 + 1
Totalx = Totalx - xx
endif

output P0
shiftout P0,P1,0,[4\8]
Pause 1
shiftin P0,P1,0,[dat\8]
SQUAL=dat

serout S_out,I9600,["X = ",sDec TotalX,"     Y = ",sDec TotalY,"  ",bin YY\8,"    SQUAL = ",Dec SQUAL,13]
                  
Pause 30
goto loop
 