Jump to content

arkleyjoe's Photo


Member Since 2 Apr 2017
OFFLINE Last Active Feb 21 2018 2:59 PM

Posts I've Made

In Topic: PF scrolling but I am not sure why.

Thu Jan 4, 2018 10:29 AM

Ahh good call I will take a look. 

In Topic: PF scrolling but I am not sure why.

Wed Jan 3, 2018 4:26 PM

BTW to add further I am really referring to the lines of code around line 86 of the ASM file.

In Topic: PF scrolling but I am not sure why.

Wed Jan 3, 2018 4:21 PM

Hi I now have a piece of code that is scrolling as I want. (attached)


My approach to getting the scrolling is to have a counter that increments / decrements each frame and I use that o push the PF along. Could anyone let me know if this is the right basic approach?


I appreciate the code is a mess right now, I just want to know I have the basic concept in place before I continue.


Your input is greatly appreciated.







In Topic: PF scrolling but I am not sure why.

Fri Dec 29, 2017 2:30 PM

Hey, thank you for coming back so quickly. Hugely appreciated.


Ok that was REALLY helpful. Using that technique, I realised that I was falling through my subroutines rather than jumping strait to Overscan once I had reached the 192 lines. This meant that I was adding a few additional scan lines. Thanks for pointing me in the right direction and thanks for the additional hint on the way I was attempting to address the play field pattern values. That has cleared up something else that was confusing me.


Now I have it stable I would like to understand how to make it scroll again in a controlled way.


If you could help me understand how to approach the scrolling I would really appreciate it.


I have attached the fixed pftest.asm


Many thanks 






In Topic: How can you build a collisons counter here?

Tue Apr 4, 2017 6:45 AM

This should be quite simple. 


You can add another variable where you currently have have y=50 add a new variable. For example:


i=0 : rem Used to count collisions. 


where you test for collision in this line.

 if collision(player1,player0) then COLUBK=$28 else COLUBK=200

You should adjust that line to increment your counter.

if collision(player1,player0) then i=i+1

That would be a simple way to do it.


I hope that points you in the right direction.