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[stepleton]

Yesterday I experimented with the Raspberry Pi-based RGBTOHDMI device, which plenty of folks out there are using to interface lots of older systems with modern displays. (You can buy complete or add-your-own-RPi kits from various online "retro" shops, or you can build your own if you like SMD soldering.) There are folks out there who've managed to get it working with their Lisas, and after a lot of fiddling, I was able to do it too; see attached image.

The device seems to produce a good result if you are patient and lucky. There seem to be one or two dozen parameters you can set which will directly affect the quality of the image you get. The project's own "Apple Lisa" profile produced a skewed, rolling image for me, and I had to spend a good hour poking around and trying different options until I got something to work. (One of the parameters had me tuning an hsync-detection threshold to somewhere inside a 20 millivolt sweet spot.) I'm not sure how reproduceable the result is across Lisas or across separate RGBTOHDMI devices.

But the settings I wound up with seem dependable for now, and it's the only tool I have for getting the Lisa to display on something from this century.

[RolandJuno]

Terrific work on getting your display working with the Lisa! I had slightly different values than DosFox. Here's what I had using 8 bit analog YUV:

sampling=7,7,7,7,7,7,7,0,1,0,10,0,0,0,0,4,1,1,1,0,79,256,256,256,256,39,256,256
geometry=164,7,552,364,720,364,2,3,1,1,20374338,896,5000,379,4,0,0
palette=Mono_(2_level)
scanline_level=0

Curious if mine is different in any way because I'm using an EPROM for the VSROM perhaps?

[andrew]

This looks like it would be a lifesaver in the event of a dead CRT.

[patrick]

In the event of a dead CRT, use some other 12" paperwhite tube as a replacement. E.g. from an Atari SM124 monitor. These have better brightness and focus than the original Clinton tube used by Apple.

In the event of some other hardware issue, just install LisaEm on your Raspberry 

[sigma7]

Terrific work on getting your display working with the Lisa! I had slightly different values than DosFox. Here's what I had using 8 bit analog YUV:

sampling=7,7,7,7,7,7,7,0,1,0,10,0,0,0,0,4,1,1,1,0,79,256,256,256,256,39,256,256
geometry=164,7,552,364,720,364,2,3,1,1,20374338,896,5000,379,4,0,0
palette=Mono_(2_level)
scanline_level=0

Per this old post, I suspect the aspect ratio of a single pixel on real Lisa hardware is more accurately 3:4 (Horizontal:Vertical)... if one of you that has an RGB2HDMI connected to a Lisa could try that and report as to whether it looks closer to the real thing it may pacify my curiosity. (Various screen images posted in the AppleLisaClone threads look too tall, but there are numerous other explanations of course.)

eg. geometry=164,7,552,364,720,364,  3,  4  ,1,1,20374338,896,5000,379,4,0,0

Curious if mine is different in any way because I'm using an EPROM for the VSROM perhaps?

What speed is your EPROM? I'm wondering if a slow video state machine works just as well as a stock one, perhaps only causing a delay in the retrace signals?

[ried]

Tom, how are you physically connecting the Lisa's composite video out port to the RGBtoHDMI device? Are you using a composite to 9-pin adapter, or something different? Thanks in advance.

[stepleton]

I basically bought a device that has a composite input, so I don't recall too much in the way of details. Let me go and have a look...

...and I'm still a bit in the dark. What I bought was this thing: https://www.sellmyretro.com/offer/details/63615 , which appears to have made use of this thing or an earlier variant of it: https://www.tindie.com/products/c0pperdragon/rgbtohdmi-mono-lumacode/ . The person who makes that thing says "Due to tax reasons, and to avoid exceeding certain yearly revenue limits, I have to stop all sales for the rest of 2024. Sorry." But 2025 is just around the corner...

The description for that project says: "This board combines a basic RGBtoHDMI board with the features of the analog add-on that are relevant for monochrome input. So it is substantially cheaper than the combination of the existing two. Also a detachable cable is already provided." So if you can't wait, it sounds like you can get a working setup by using the "main branch" RGBtoHDMI and plugging the "analog board" into it.

[iJol]

In the event of a dead CRT, use some other 12" paperwhite tube as a replacement. E.g. from an Atari SM124 monitor. These have better brightness and focus than the original Clinton tube used by Apple.

In the event of some other hardware issue, just install LisaEm on your Raspberry 

Sorry for off-topic, but should this work? My Lisa 2/10 CRT is pretty worn out and I want to replace it for a year now. The Atari monitors are quite cheap here so if this work I'll try it out.

[patrick]

Yes, the Atari CRT (Goldstar 310KAB4K) runs perfectly in the Lisa. One of my machines had heavy burn-in marks as a result of a defective vertical deflection. It now has just such a tube in it.

You have to keep the original deflection yoke from your Lisa. To rotate the picture, rotate the yoke assembly. To move the picture, use the two ring magnets at the CRT neck. Rotate them together or against each other until you have best geometry, then use the pots on the Video Board for fine tuning.

[ried]

Thanks to the brilliant folks on this forum, even I was able to get the RGBtoHDMI up and running:




I thought it would be fun to use an Apple Studio Display (DVI) to match the Lisa's translucent bezel, so went with a Lisa component video > RGBtoHDMI > HDMI to DVI converter to create the result seen here. 1024 x 768 isn't a perfect way to show off Lisa Office System's geometry, of course. But it's certainly usable and looks neat.

[ried]

Any educated guesses about the values needed to support a Mac XL with the screen modification? It's certainly different than the 2/10 LOS 3.1 configuration, and I'm having trouble dialing in the correct changes.

[AlexTheCat123]

I remember playing around with it a while back, and I think I eventually gave up and switched to H ROMs because I was never able to get it dialed in with the screen mod. But maybe someone else who's had better luck can help.

[bmwcyclist]

Can you please post the pi zero disk files you used?

[AlexTheCat123]

I just used the stock files from the RGBtoHDMI GitHub, which you can find here. It comes with a Lisa profile, so just select that and everything should work. I still haven't managed to get it dialed in with the 3A ROMs, but the included profile will work great for other ROM revisions.

[bmwcyclist]

So far, no luck with the RGBTOHDMI.

Using the profile listed here as well as the default lisa profile I get about the same thing which is this:

https://youtu.be/2wp9vRLRlvY?si=N77olSSK0qKYGytE

I've tried changing and rotating through the Settings menu, geometry, and sampling menu. Nothing seems to improve the screen.

Any suggestions?

Are there any other products that might work?