'June 19, 1999 Button one did not work very well. Trying alternate method.
'This method works great! PBP 2.2 392 words

DEFINE OSC 10


OPTION_REG.7 = 0

trisb = %11110000

rx1 var portb.0
rx2 var portb.1
rx3 var portb.2
rx4 var portb.3

cy1 var portb.4
cy2 var portb.5
cy3 var portb.6

key var byte
key = 0

loop:
  
  rx1 = 0
  pause 10
  gosub getkeya
  rx1 = 1

  rx2 = 0
  pause 10
  gosub getkeyb
  rx2 = 1

  rx3 = 0
  pause 10
  gosub getkeyc
  rx3 = 1

  rx4 = 0
  pause 10
  gosub getkeyd
  rx4 = 1

goto loop

getkeya:

  if cy1 = 0 then
    key = 1
    gosub tones
    gosub waita
  endif

  if cy2 = 0 then
    key = 2
    gosub tones
    gosub waitb
  endif

  if cy3 = 0 then
    key = 3
    gosub tones
    gosub waitc
  endif

return

getkeyb:

  if cy1 = 0 then
    key = 4
    gosub tones
    gosub waita
  endif

  if cy2 = 0 then
    key = 5
    gosub tones
    gosub waitb
  endif

  if cy3 = 0 then
    key = 6
    gosub tones
    gosub waitc
  endif

return

getkeyc:  

  if cy1 = 0 then
    key = 7
    gosub tones
    gosub waita
  endif

  if cy2 = 0 then
    key = 8
    gosub tones
    gosub waitb
  endif

  if cy3 = 0 then
    key = 9
    gosub tones
    gosub waitc
  endif

return

getkeyd:
  if cy1 = 0 then
    key = 10
    gosub tones
    gosub waita
  endif

  if cy2 = 0 then
    key = 0
    gosub tones
    gosub waitb
  endif

  if cy3 = 0 then
    key = 11
    gosub tones
    gosub waitc
  endif

return


waita:
  while cy1 = 0
  wend
return

waitb:
  while cy2 = 0
  wend
return

waitc:
  while cy3 = 0
  wend
return

tones:
  dtmfout porta.3, [#key]
return