Zx Spectrum 128k +2 (SCART to VGA or HDMi)

[1024MAK]

ZX-HD <snip>
It connects to the edge connector and I believe eavesdrops on writes to screen memory. It keeps its own internal screen buffer and then just renders it to the screen.

It does. Both this and the Spectra (SCART interface plus various other functions) ignore the output from the existing video system (ULA/gate array) and instead implement their own video system. Every time the processor writes to the screen memory area (which on the ZX Spectrum range is in the same area) they capture the data from the data bus on the edge-connector/expansion port. Hence they have the display data as digital information.

Using the digital display data, they can then process it however they like and hence can output new sharp video streams. This is a much better method than sampling the original output from the ULA, or worse, the composite video signal.

Mark

[Flatulentia]

Using the digital display data, they can then process it however they like and hence can output new sharp video streams. This is a much better method than sampling the original output from the ULA, or worse, the composite video signal.

From a purely technical perspective, this is clearly the best way of doing it, but it's also over 20 times more expensive than the cheapest alternatives. I guess it depends on whether a person wants the output to look like it's come straight from an emulator or from the real thing.

Assuming I've not bought a duffer on eBay, I'll be experimenting with a +2 when it arrives to see just how clean and crisp it's possible to get the output with all of the known composite clean-up mods (which I'll be doing anyway) plus one of my own mods and a £4 MINI AV2HDMI converter.

It'll probably end up installed internally if I'm happy with it, so that'll be one less external device to deal with.

It's a similar argument to CD vs vinyl. Anyone who knows their stuff knows that CD is vastly superior, but vinyl can still sound "nice".

[1024MAK]

Well, for the 128K models (toastrack, +2 grey, +2A, +2B, +3, +3B), the RGB output is more than good enough for a nice crisp display on a RGB SCART TV, or on a monitor that accepts the signals from the Speccy.

Some standards converters will work with the RGB signals (once some resistors have converted it to “analogue” RGB levels.

Mark

[Flatulentia]

And that's the crux of the problem. I'd love to use RGB, but I'm in the same boat as millions of others with no choice but to use either a UHF TV signal, DVI or HDMI as none of my displays support anything else.

I've looked at several converters on eBay and Amazon for around £30 that clearly state "RGB to HDMI" when what they actually support is YCbCr to HDMI using red, green and blue RCA sockets.

It makes me wonder how many people have boxes full of completely useless converters under their beds because they can't be bothered to keep sending them back.

[1024MAK]

Well, that gets us back to the “RGB to HDMI using a Pi Zero and a small CPLD project” which is known to work…

Mark

[Flatulentia]

...and costs twice as much ready built as I paid for the +2.

[Lardo Boffin]

I have bought several TVs from charity shops as they tend to be older and support RGB SCART.

They have all been less than a converter and of course you are helping a good cause.

[mikeh_nz]

If you have a computer with RGB output, then a monitor with SCART input is totally fine.

I started out trying to get my Beeb’s RGB output on something. With no SCART TVs here in the USA, I ended up looking at Sharp LCD TVs with SCART on Amazon UK. But, at £150 +shipping to USA, it was much more economical to go the “RGB to HDMI” route.

It’s all relative costs I guess. I’m jealous of the ability to go into a charity shop and find this stuff. I love Lardo’s idea.

[Flatulentia]

I love Lardo’s idea.

Me too. That's exactly what I'd do if I had room for one. It looks like I'll just have to settle for composite to HDMI.

That's not necessarily terrible though. I was watching this video last night to see just how good it's possible to get the composite video looking if you're handy with a soldering iron.

https://www.youtube.com/watch?v=GMKGIP5Yuqs

It's never going to be perfect, but it's an enormous improvement over the standard composite video output.

[Paul]

Did yo know this?
https://forum.tlienhard.com/phpBB3/viewtopic.php?t=4283
Pico based RGB to VGA for QL at nearly no cost.
Also capable of spectrum video.