Print

[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.