I used a SIPO register as describde below, but connected the enable and
ACK lines together. I could not get the 4 bit mode to work. I am using a
16C57 for this. If you would like more info, please let me know.

Paul B. Webster VK2BZC wrote:
>
> ERIC SCHLAEPFER wrote:
>
> > Hi Dave,  ( And everyone else who replied to my cry for help. )
> >
> > Looks good. I'll have to try the file out. Also, if the I/O is write
> > only, that means a shift register could be put in to shift out 4-bit
> > data using only 2 I/O lines. Add 2 data lines to the E line and the
> > C/D line, and you have 4 I/O pins for the LCD. Not bad.
>
>   While you *could* use an extra data bit from a SIPO shift register
> (74HC164) to provide the C/D signal, using a shift register to provide
> the Enable bit as well requires a latched shift register (74HC595) which
> in turn requires an extra Latch Enable bit so you are not winning.
>
>   I think it would be easier to use an 8-bit non-latched shift register
> and 8-bit transfer mode.  Remember that the two inputs to the shift
> register and/ or all eight outputs; and the PIC pins used for the C/D
> (and R/~W) are all share-able for other output, and even input
> functions, only the enable function is unique.
>
>   Cheers,
>         Paul B.