> I was wondering if you could modify his design to use a 16c84
> and have the dtmf chip and the lcd use some of the same
> data lines and seperate enable lines? Does this seem possible
> or would you potentially lose some dtmf tones comming in?
> (I'm new at this stuff....).


Hmmm.

 Typical LCD - 4 data lines, R/W, E, RS       total 7 lines
 Typical DTMF - 4 lines only, maybe five      lets say 4 lines
 Serial EEPROM, clock and data                total 2 lines
                                              13 lines = 16C84

You could probably make it work without too much hassle.
I guess control control input keys, but DTMF could be used for this also.
You can use the EEPROM clock without a start condition as one of
the LCD lines (say RS) to free anothr line. This could be used with a diode
on the 4 LCD data lines to give a 4 key keypad.

piece of cake <-:

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