[rescue] Old Monitors

[Jonathan Patschke]

On Thu, 15 Feb 2018, Mouse wrote:

> Well, you need some form of memory, whether it takes the form of RAM,
> or phosphor persistence, or even human-eye persistence. :-)

I was referring to the problem that as your effective resolution
approaches being relatively prime to the actual display resolution, clever
scaling needs doing or everything gets Bresenham'ed to crap.  Folks in the
vintage video-games emulation community have played with different scaling
algorithms since at least the mid-1990s, and there are few
computationally-cheap ones that look okay.

I saw a computationally-expensive algorithm that came out of Microsoft
Research (I think) a couple of years back that produced _amazing_ results,
but it didn't look like something that could provably run in bounded time.

> But, really, what makes the most sense to me is to put the memory with
> the pixels: each pixel of screen includes not just driving electronics
> but 24 (or whatever) bits of RAM to store that pixel, plus enough logic
> to support the scan decoding logic writing to those bits - though this
> seems obvious enough there probably is some reason it's difficult to do
> or it would have already been done.

Yes, you _can_ do just that, and many companies have.  The results are
ugly for anything other than an input signal that assumes the native
resolution of the panel.

CRTs are more-or-less analogue (w/r/t resolution) down to a certain
dot-pitch floor.  The pixel clock doesn't need to perfectly match the
shadow mask; phosphor makes a great integrator.  A Cartesian grid of
pixels is not as forgiving, hence the need for creativity to replicate the
CRT smoothing/scaling effect.

> Personally, nothing involving HDMI is fun.  Supporting HDMI is negative
> when I'm looking for a computer; supporting nothing but HDMI is a much
> bigger negative.

I guess it depends on how many yaks you want to shave.  For all its evils,
the market presence of HDMI provides a great abstraction later for
connecting an arbitrary display panel.  DisplayPort is better from a
licensing point-of-view, but is rarely present on the cheaper development
boards.

-- 
Jonathan Patschke
Austin, TX
USA