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Last updated on Oct-18-2019 Download

safe areas for ntsc tv on the NES

safe areas for ntsc tv on the NES
by on (#25009)
im sure its documented somewhere but i spent some time looking for the info - which parts of the screen shouldnt be drawn on for this purpose? im working on some artwork for the nes... i dont want to waste time making things that arent going to look correct on real hardware - if anyone knows off hand... thanks

~alex mauer

by on (#25020)
The entire drawing area is considered "safe," in the sense that it'll work fine. However, on older TVs, the top and bottom 8 pixels might be covered up by the TV case, so you might want to make sure there's no important information in that area.

by on (#25021)
commodorejohn wrote:
so you might want to make sure there's no important information in that area.

But that's exactly what the television jargon term "safe area" means.

The specs used by the BBC are as follows:
  • Title safe area: 5% to 95% of each dimension; put all important info there
  • Action safe area: 3.5% to 96.5% of each dimension; artifacts are OK outside this

The entire width of the NES picture is inside the action safe area. The sides of the title safe area are at x=0 and x=252 on the NES PPU. Vertically, the action safe area is y=8 to 231, and the title safe area is y=12 to 227. This means that in theory, if you're making a 4-way scrolling game without a status bar, it's better to use vertical mirroring like Super C.

by on (#25023)
All analog TVs have some degree of "overscan" (that is, the portion of the screen that's cut off at the edges). The portions of the screen that get cut off will vary depending on the TV set, so there's no hard rule. One of my TV's cuts off around 14 pixels from the top and only a couple from the bottom. Another TV cuts off around 8 pixels from both the top and the bottom (this is more typical).

Overscan is not an issue on the left or right side of the screen, because the NES generates margins on both sides to allow for overscan. However, graphics near the left or right side might still get cut off due to screen curvature.

by on (#25025)
The 8 on top and bottom cutoff is so common that lots of people just say the NES's resolution is 256x224 (PPU renders 256x240).

I've seen some TVs cut off a lot more. I remember playing Legacy of the Wizard at a friend's house, and we were stuck for a long time at the very beginning because we couldn't see the ladder on the floor. Eventually we noticed a couple of odd pixels and managed to go down there.

by on (#25043)
Quote:
This means that in theory, if you're making a 4-way scrolling game without a status bar, it's better to use vertical mirroring like Super C.

Is that because then, on a real TV you get 90% of chances having vertical glitches hidden instead of having 20% of chances having your horizontal glitches hidden ? On a PAL screen, on the other hand, you have 100% of chances seeing the glitches either way.