Commander X16

can't i just use a 1280x1024 and live with the 64 pixel black bar at the bottom?

On 10/30/2022 at 3:04 AM, BlahDehBlah said:

can't i just use a 1280x1024 and live with the 64 pixel black bar at the bottom?

Most monitors don't work that way. Instead they will stretch input 480p signal to 1024 pixels resulting in some scaling artifacts. But it does not look too bad. Here is a photo if 640x480 pixels input stretched out to 1280x1024 pixels screen.

Another great modern solutions is to use monitor with as high resolution as possible, say 7680x4320. By the way this particular resolution perfectly scales to 640x480 in 4:3 mode. But even if your monitor does not scales perfectly, pixels in high resilution monitors are so tiny, that you will barely see scaling artifacts. I think this will be the path most X16 users will take.

On 10/30/2022 at 3:04 AM, BlahDehBlah said:

can't i just use a 1280x1024 and live with the 64 pixel black bar at the bottom?

Thoretically is is possible to build a video signal converter. If one take a powerfull microcontroller that can cope with VGA signal speed, then it can pass VGA signal through itself adding these 64 black lines. This might be a challenge to implement though.

On 11/6/2022 at 2:19 AM, Cyber said:

Another great modern solutions is to use monitor with as high resolution as possible, say 7680x4320. By the way this particular resolution perfectly scales to 640x480 in 4:3 mode. But even if your monitor does not scales perfectly, pixels in high resilution monitors are so tiny, that you will barely see scaling artifacts. I think this will be the path most X16 users will take.

How many monitors at that resolution have scan multiplier hardware?  It would be awkard to have the image to occupy the central 1/144 of screen real estate with the rest being a very black "picture frame" effect.

On 11/6/2022 at 5:34 PM, Kalvan said:

How many monitors at that resolution have scan multiplier hardware?  It would be awkard to have the image to occupy the central 1/144 of screen real estate with the rest being a very black "picture frame" effect.

Why would you think that? X16 output on such monitor will use 9x9 pixels for every one pixel, and thus image will be fullscreen with black borders on left and right because of 4:3 mode.

On 11/6/2022 at 10:34 AM, Kalvan said:

How many monitors at that resolution have scan multiplier hardware?  It would be awkard to have the image to occupy the central 1/144 of screen real estate with the rest being a very black "picture frame" effect.

I think you can be very confident that monitors with pixel density much finer than most of the input signals they will be showing were designed from the ground up to fill the screen as the default option.

Asfair, DCT is the algorithm used to scale a video signal of the wrong size to fit the flat screen panel of a fixed pixel size. A standard procedure since flat panels became a thing. If the builtin  hardware detects that the input have the same pixel format as the physical panel, the transform is likely omitted. Regardless, if 4 input pixels is to be fitted on 5 output pixels there will be a compromise regardless of the solution.

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

More:

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

Handled by an ASIC in displays. And with a DSP maybe ~1000 instructions per output pixel might be needed?

On 11/6/2022 at 2:28 AM, Cyber said:

Thoretically is is possible to build a video signal converter. If one take a powerfull microcontroller that can cope with VGA signal speed, then it can pass VGA signal through itself adding these 64 black lines. This might be a challenge to implement though.

is there some way to have different versions of the kernal to support these 5:4 resolutions? Or is the VGA signal generation solely (or mostly) done in hardware and would require board modifications?

On 11/7/2022 at 5:06 AM, BlahDehBlah said:

is there some way to have different versions of the kernal to support these 5:4 resolutions? Or is the VGA signal generation solely (or mostly) done in hardware and would require board modifications?

VGA signal is generated by VERA, and despite there is no room for such logic, it was never planned to do such thing, and it is not a video module responsibility in the first place. X16 is a retro system and its output is 640x480. Scaling to different resolution (if needed) is a responsibility of some other external device.