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by weinzierl10 hours ago |
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upvoteby noone_youknow9 hours ago|
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In the context of the Amiga you didn’t need to change the signal frequency, the underlying video signal stayed the same.

For wider pixels, the hardware just drew each pixel for longer, and for taller pixels each pixel spanned more lines.

Pixels weren’t real in the CRT days :)

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upvoteby fallat8 hours ago|
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In a sense pixels arent even real today right? It's an abstraction
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upvoteby kstrauser7 hours ago|
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Kinda, but a CRT literally doesn’t have precise pixel targeting in the way an LCD does. Instead, you’re telling the electron gun to draw red for a little while, and it paints what it paints.
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upvoteby layer85 hours ago|
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LCD and OLED panels consist of a fixed, unchangeable matrix of native pixels. (Same for the discontinued Plasma TVs.) CRTs don’t have that.
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upvoteby jdswain2 hours ago|
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[dead]
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upvoteby fredoralive9 hours ago|
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It’s basically just an SD TV signal, the vertical height in lines doesn’t change, it largely just swaps if each line outputs 320 or 640 pixels during its assigned time period.

Having interlaced and non interlaced modes at once seems a bit funky though, but I assume it just forces everything into interlaced with the non interlaced mode sections having the same line sent on both fields?

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upvoteby amiga3865 hours ago|
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In TV land, there is no non-interlaced. It's all interlaced. You provide fields at 50Hz/60Hz* and the CRT displays one after the other, interleaved.

https://en.wikipedia.org/wiki/Interlaced_video

"Non-interlaced" is just sending the same line for both fields, "interlaced" is sending different lines for each field. You can update your "non-interlaced" screen at 50/60Hz and the viewer will see movement, because it's transmitted for both fields. If you were updating just one line of an interlaced screen at 50/60Hz, it would only be transmitted every second field, so the viewer would perceive 25/30Hz movement.

For high-resolution monitors, Commodore and 3rd parties offered a "flicker fixer", which took the raw output, buffered both fields in its own RAM, and re-emitted the combined image as a single frame.

https://en.wikipedia.org/wiki/Flicker_fixer

*: actually 59.94Hz

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upvoteby ack_complete2 hours ago|
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No, there is actually a difference between an interlaced and non-interlaced signal. A non-interlaced signal has an integral number of lines per field without the half-line that an interlaced signal would have. With a non-interlaced signal, a classic CRT will scan all of the fields with the same alignment instead of interleaving even/odd fields vertically. There was a definite visual difference between a non-interlaced mode and an interlaced mode repeating the same screen for both fields.
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upvoteby kmeisthax8 hours ago|
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Analog monitors don't care about the dot clock. They draw lines, but you can put whatever signal you want in the lines so long as the dot clock doesn't exceed the available bandwidth. So horizontal resolution is effectively a range you can change at any time and the monitor won't even notice.

Vertical resolution is very much part of the spec, but even then CRTs will sync to hilariously out-of-spec signals that gain or lose lines per frame. Sanely-designed graphics hardware like the Amiga wouldn't do this, but the Atari 2600 wasn't sanely designed and had plenty of games that played fast and loose with NTSC. Atari graphics hardware only generated a single line of graphics and relied on H-Blank effects for literally everything else. Even the vertical retrace signal was controlled by the game. So it was very common to see badly programmed games send too many lines, and a different wrong number of lines each frame, which nobody noticed until people started writing 2600 emulators.

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