What am I doing wrong here? (Sprite help, please)

[PacManPlus]

Hi:

 

First the details of what I am trying to do:

 

Screen Mode: 320A

Sprite Size: 8H x 16W (2 bytes per line)

Screen zones: 208 mode lines, 26 zones, 8 lines per zone. 17 blank lines above, 18 blank lines below for a total of 243 lines.

 

I started with Dan Boris' sprite demo, but I can't seem to get it to work like this. First the sprite disappears as it is moving vertically, followed by white bars, and then it only moves half the screen width down before stopping.

 

I know this must be something stupid I'm doing, I hope someone can help me. Also, you will be able to tell by the sprite which game I'm going to try and implement.

 

The source and compiled binaries are attached below.

 

Thanks in Advance,

Bob

7800SPRT.ZIP

Edited December 1, 2006 by PacManPlus

[kenfused]

Hi:

 

First the details of what I am trying to do:

 

Screen Mode: 320A

Sprite Size: 8H x 16W (2 bytes per line)

Screen zones: 208 mode lines, 26 zones, 8 lines per zone. 17 blank lines above, 18 blank lines below for a total of 243 lines.

 

I started with Dan Boris' sprite demo, but I can't seem to get it to work like this. First the sprite disappears as it is moving vertically, followed by white bars, and then it only moves half the screen width down before stopping.

 

I know this must be something stupid I'm doing, I hope someone can help me. Also, you will be able to tell by the sprite which game I'm going to try and implement.

 

The source and compiled binaries are attached below.

 

Thanks in Advance,

Bob

White Bar is probably the wrong holey dma mode is specified. You want the smaller one for 8 pixel high zones.

Part of the sprite disappearing as it moves down is probably some miscalculation from the y position when determining the address to store when the sprite extends into the next zone. I know the upsidedownness of the graphics sometimes trips me up on that.

 

--Ken

[PacManPlus]

Thanks, Ken:

 

It looks like that was it!

 

Bob

[+Mitch]

Helicopter game??

 

Mitch