In the original 08M code ...
Do
:
b0=b0 and %00000000
Let dirs=b0
Readadc 4, b0
Loop while b0 > 80
That makes all pins inputs, reads the analogue connected to pin 4 and repeats what's in the loop until the analogue level drops below 80.
The important thing though is "Why?". What is the purpose of doing that, what does it achieve and what is the program trying to determine is happening ?
Where does the analogue on pin 4 come from ? How is pin 4 used, and to what purpose ?
I'll be surprised if you can answer all those questions and without that knowledge you won't get far with converting the code to a 14M.
The clue to what is happening comes from other uses of pin 4 in the program ( and in that loop of the above code ), where it is also used as an output. Very strange until you understand what's going on, then it becomes crystal clear.
Pin 4 is connected to one of the triggers. That can be read as an analogue input, a low reading when pulled in, a high reading when released ( or vice-versa ). So what this code is doing is determining whether the trigger is pulled-in or not.
To do auto-fire, the trigger needs to be automatically pulled. This is done by using pin 4 to override the trigger; a pulse out on pin 4 simulates pulling the trigger. What the code does is automatically fire one shot, check if the trigger is released, if not fire another shot. To read the trigger pin 4 must be an input ( hence dirs= ) and to control the trigger pin 4 must be an output and pulse ( HIGH 4, LOW 4 ). Pin 4 is dual function.
Porting the code to a non-08M requires the same dual function use to be achieved, but on different hardware. On a 14M output pin 4 and ADC 4 are no longer on the same pins, so you need a different hardware design.
In this code it is only single trigger and you will be requiring dual trigger control. In the 08M version I recall that this used pin 1 or pin 2 for the second trigger. That's more complicated because pin 1 and pin 2 cannot be made inputs which means moving them to another pin which can be.
The first thing you need to do is come up with a hardware design, define what pins connect where, then write the code which can achieve what you want, test that on real hardware and make it work. After that you can chain the code you have into a functioning program which does all you want it to.
It's more complicated than just editing code as you are making a significant change to the hardware and need to know the consequences of that. The hardware design rests upon understanding how the hardware works and the PICAXE capabilities. It's an iterative process - Knowing what you need to achieve, designing hardware to allow it to be achieved, writing code to achieve it.
In starting with editing the code and not having a system design you are largely doomed to failure; you don't know what the change needed is or if it will do what it needs to achieve.
It's not a project I'd recommend as a first PICAXE programming exercise, and involves some electrical knowledge as well as software skills, but it can be done. I would suggest getting a basic PICAXE-08M starter kit to run programs upon and to test things out as that, IMO, is the best way to get to understand how the PICAXE works.