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Interestingly the '240p' signal sent out by video game consoles of that era is really a hack, as 240p wasn't a standard signal supported by TVs of the time. It
by p1necone 6y ago
Interestingly the '240p' signal sent out by video game consoles of that era is really a hack, as 240p wasn't a standard signal supported by TVs of the time.
It's actually a 480i signal with the timing fiddled with so that the alternate lines still strike the same part of the screen (this is why games from that era had such noticeable scanlines - the CRT beam is only lighting up alternate horizontal lines).
This also means that a lot of more modern TVs (and even some upscalers marketed for retro gaming) do an extra terrible job of upscaling 240p signals because they run the same logic that they would if it was normal 480i, resulting in unnecessary flickering or dropped frames.
- gmueckl 6y agoWait, what kind of analog TV signal allows for that kind of control? Are you sure that they didn't just scan out the same framebuffer twice?
- entropicdrifter 6y agoEssentially all pre-HD analog TVs allow for that kind of control. https://www.hdretrovision.com/240p https://www.hdretrovision.com/240p
- toast0 6y agoThe Analog TV doesn't have a framebuffer, and neither do most consoles, until you get into the 3d era. My understanding is that the timing of the vblank signalling that comes between fields determines weather the next field is an even field or an odd field. If the vblank signalling comes in the middle of the last scanline, the next field is an even field; if the vblank comes aligned with the end of the last scanline, the next field is an odd field. If you always start vblank signalling in the middle of a scanline, you get all even fields, if you always start vblank signalling at the end of a scanline, you get all odd fields.