Pixel aspect ratio

[mmastrac]

The aspect ratio of the display should be approx 4:3, which means the current square pixels are wider than they should be.

[j4james]

Based on screen captures I've got from a VT525 (which I think has the same basic dimensions as the VT420), I believe the scaling factor is likely 1.25. When using the default 80x24 page size, it looks to me like a pair of text cells side by side should form a perfect square. A single text cell is 10x16 pixels (width by height), so a pair of them will be 20x16, and thus to make that a perfect square you need to scale the height by 1.25 (16 * 1.25 = 20).

[mmastrac]

It looks like the pixels library doesn't currently handle square pixels (waiting on parasyte/pixels#151 to land). It might be possible to work around this with a custom shader.