Maria Diagram

[+xucaen]

Back in 2005-ish when I was learning Atari 2600 programming, I found it very helpful to have the Tia Diagram image. Once I saw that, the scan lines made sense to me. Perhaps it wasn't necessary, but I took the maria diagram from the last page of the 7800 Software Guide updated and made a .PNG image out of it. I find it helpful to be able to see the scan lines and pixels laid out like this. Maybe others will find it useful, too.

 

 

[Trebor]

Back in 2005-ish when I was learning Atari 2600 programming, I found it very helpful to have the Tia Diagram image. Once I saw that, the scan lines made sense to me. Perhaps it wasn't necessary, but I took the maria diagram from the last page of the 7800 Software Guide updated and made a .PNG image out of it. I find it helpful to be able to see the scan lines and pixels laid out like this. Maybe others will find it useful, too.

 

 

maria_diagram.png

 

While the 192 lines reference (A 'carry-over' from the 2600 days) is utilized by some games, there are 7800 games that go much higher.

 

For example, Water Ski and Tank Command both utilize 224 lines, the more common reference bar for console systems of the 3rd generation era. The homebrew Donkey Kong PK / XM pushes close to 224.

 

In the below comparison, with a visible area of 224 vertical lines, Ms. Pac-Man appears to be in the 192 range, while Ballblazer fills more of the screen appearing in the 208 visible range, and Water Ski fills the screen completely from top to bottom with 224 lines:

 

 

Additionally, with 7800basic, as noted here, there is the "screenheight" option of 192, 208, or 224 lines. Depending on the particular game's needs and/or developer's desire, having flexibility in this area may be helpful.

[+xucaen]

That's interesting. How are they able to cram an extra 32 lines in addition to the 71 lines of vertical blank? It's sounds like that might be a little more advanced than where I am at right now. Thanks for letting me know. I'll put it in my notes for later.

[Mord]

That's interesting. How are they able to cram an extra 32 lines in addition to the 71 lines of vertical blank? It's sounds like that might be a little more advanced than where I am at right now. Thanks for letting me know. I'll put it in my notes for later.

 

Essentially it just steals lines from the vertical blank rather than adding new lines. So if you increase the vertical resolution to your program, expect there to be less time off-screen to do calculations.