Confusion over sprite graphics

[xucaen]

I am trying to figure out how to enter sprite graphics for the 7800 and I am confused about the examples I am seeing.

 

For example, an Atari 2600 sprite looks like this:

Sprite0 .byte #%11000011
    .byte #%10000001
    .byte #%10011001
    .byte #%01011010
    .byte #%00111100
    .byte #%00011000
    .byte #%00011000

but that same exact sprite for some reason has to look like this?

;Sprite0
org $a000
.byte #%00000000
org $a100
.byte #%00000000
org $a200
.byte #%00000000
org $a300
.byte #%00000000
org $a400
.byte #%00000000
org $a500
.byte #%00000000
org $a600
.byte #%00000000
org $a700
.byte #%00000000
org $a800
.byte #%00000000
org $a900
.byte #%11000011
org $aA00
.byte #%10000001
org $aB00
.byte #%10011001
org $aC00
.byte #%01011010
org $aD00
.byte #%00111100
org $aE00
.byte #%00011000
org $aF00
.byte #%00011000

I was wondering why do I need the ORG statements and why do I have to have 16 bytes? It seems to be much easier and more straight forward to make sprites for the 2600 than it is for the 7800. Is there a better/simpler way to do it for the 7800?

[Mord]

The reason for that is that MARIA decreases the high byte for every line of the sprite as it processes a zone. As a result each line of the sprite is separated by $100 as you see in the sprite. There's no easy away around it as that's how MARIA expects the data to be organized.

[Roy]

There is an old program HERE that I used for my wip game. Maybe it can export in a format you can use? I had to manually enter my graphic information into a binary and include it into the assembly due to using a different assembler...

[EricBall]

7800 sprites may be more than a single byte wide (and can have some interesting bit to pixel mappings). Therefore putting each row on a separate page means MARIA doesn't have to perform any multiplication to get the data for the next row.

 

7800 sprites are also "upside down" - i.e. the lowest memory address contains the bottom row of the sprite.

Edited October 27, 2015 by EricBall