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Comment by jonny_eh | Hacker News Reader

Targetting 320x256 makes it harder to port to 320x200. Meanwhile, porting 320x200 to 320x256 is easy, just add a small letterbox.

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I always thought 256 vs 200 was a PAL vs NTSC thing? Is that wrong?

Ya, depends on the system. For example, the NES is 320x224 (NTSC) and 320x240 (PAL).

I can't speak to why they differ exactly though.

The number of lines per second is constant, but you get 50 frames per second on PAL and 60 frames per second on NTSC.

Actually the number of lines per second is not constant, but the overall video BW is “similar”. In terms of analog TV, PAL has at the same time lower refresh rate and higher channel BW, which in terms of computer resolutions means that NTSC is exactly 640x480 (as that is derived from NTSC timing) while PAL is something like 800x600. Home computers for all the time where that class even existed simply didn’t have both the framebuffer sizes and video BW to generate full resolution video, so the resolutions ended up halved (and in analog TV there is no horizontal resolution to speak of, so 320 is just as good number as any)

Constant-ish.

320x200x60 = 384k lines 320x256x50 = 410k lines

Akshually, the horizontal (BW) resolution has little to do with timing. It's as good as the analog components are and as good the computer can output. Amigas had 1280x256 resolution, if you wanted, on standard PAL equipment. (On a fuzzy TV set, you weren't likely to appreciate 1280 horizontal resolution though.)

You need to ignore the horizontal resolution and count the blank areas as well: PAL = 25 * 625 = 15625, and NTSC = 29.97 * 525 = 15734.25.

Haha I wasn’t thinking straight! Good thing I used 320 in both examples

Not wrong but the Atari ST's low resolution is 320 by 200, even for PAL, so targeting that resolution is helpful if you want to target both machines

It certainly was on the Amiga.

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