Scroller issue

[BacchusFLT]

Spiro,

I do believe there is a small issue in the myscroll4.asm.

Row 173 and onwards is this:

dec	scroll_offset
// bpl	reset_delay
bne	reset_delay

I do believe the BPL you commented out is the correct instruction and not the BNE.

You should count the smooth scroll value down from 7 to 0, and on the frame after being zero you should set it to 7 for that screen. But it should be 0 for a frame. If you DEC and do a BNE, you aren't allowing the value to be zero on a frame which means that on every 7th screen you make a two pixel skip. You are counting from 7 to 1 and then setting it back to 7.

With the BPL you allow it to be 0 and only set it to 7 when the DEC has rendered the value to be wrapping from 0 to ff. So with the BPL you get a scroll of one pixel on every 8 frame.

[spiroharvey]

Thanks for that, good spotting and sorry for the late reply.
I must have been messing around and forgot to put that back.

At the moment, something is wrong with my machine and I'm not able to run some of these programs properly and I haven't touched them for quite some time.

But I'll hopefully have some time over the weekend to get back to this and do some debugging.