Hey Steve,

>I have a problem !

Okay...

>The software nearly works on a 73A jw but will not initalise the LCD properly
>on ICEPIC
>
>Problems found so far.
>1. RA4 needs a pull up resistor (digital output to LCD RS)

RA4 is (always) an open-collector (open-drain) pin.  You will always have to
use a pull up if you are using it to drive something.

>2. Some difficulties with ADCON1 messing up the RA port seem to have fixed
>this by turning off the A-D until required.

What are the bits that you are using?

>3. RA4 being assigned to TOC1 Fixed by setting the corect bit in the option
>reg

???  I thought RA4 was being connected to the LCD RS.

>4. I dont think that timing is the problem as the LCD code is ported from
>working unit on '84 and OSC is 4.00 on both parts.
>
>What else interfears with RA port (RA5 is LCD EN) and RC0-7 is data has
>anybody any ideas sanity is rapidly departing

What are the RAx pins that you are using and for what purpose?  Note that on
the '73A, the least number of analog pins that you can have is three (RA0,
RA1 and RA3 for Analog Input or VRef) if you want to use analog (this is
shown in Figure 13-4 of the PIC16C7X Data Sheet) - these pins cannot be used
for anything digital.

Or if you try, it ain't gonna work.  As Andy Kunz just wrote you should
probably look for another port to use.

Good luck,

myke

Check out "Programming and Customizing the PIC Microcontroller" at:

http://www.myke.com