How common is a VT100 w/out the AVO add-on today?

[legalize]

The base VT100 has the Advanced Video Option (AVO) as an add-on to give you the additional attributes (underline, blink, bold, in addition to reverse video), additional video RAM to support 132x24 screen layout and the ability to have additional ROM/overlay ROM on top of the base VT100 ROM.

If you have a VT100 without the AVO, then please chime in on this thread. I would like to know how common this is with VT100s out in the wild in the hands of collectors.

 

[legalize]

My motivation for asking is that I've been wondering about making a modern AVO board for the VT100. The AVO is basically just a few components: RAM for the extra attribute bits, RAM for the extra screen space needed for 132x24, optional ROM overlays/additions, and latches for the attribute/video data. IIRC, there's also a space on there for an alternate character set ROM.

If we make a modern replacement for the AVO, then we have the option of using flash memory instead of ROM giving you the ability to update custom ROM into the VT100 without having to burn EEPROMs.

Extending this idea even further would be to make another board for the STP (Standard Terminal Port) that allows custom ESC sequence processing to give you the ability to upload custom fonts and firmware into the VT100.

Now, I haven't done any computation on the timing to see if it's possible, but I have this crazy idea that with those two boards in a VT100 you might be able to make it play space invaders in the ROM . I'm not sure if the 8080 is fast enough to keep up with the computation needed to update the display fast enough, but I have a sneaking suspicion it might be possible. Maybe PacMan would be more within the computational budget of the 8080 because there's fewer portions of the screen it would have to update each frame. Naturally if you add a coprocessor or even use the graphics port to completely overlay the screen it's doable. However, it feels more retrohackery to have the existing 8080 inside the VT100 do the game loop.

 

[saipan59]

My limited experience is from within CXO in the 80's: Everyone had a VT100 on their desk, and they were always ordered with the AVO pre-installed.

Pete

 

[Teletech]

I think I have six VT100 and four or five AVO

 

[leegleason]

Back in the day, I mostly saw VT100s that had a 3rd party card to provide AVO. It had much fewer components than the DEC AVO option, and was lots cheaper. Don't recall the manufacturer.

 

[larsbrinkhoff]

Now, I haven't done any computation on the timing to see if it's possible, but I have this crazy idea that with those two boards in a VT100 you might be able to make it play space invaders in the ROM . I'm not sure if the 8080 is fast enough to keep up with the computation needed to update the display fast enough, but I have a sneaking suspicion it might be possible. Maybe PacMan would be more within the computational budget of the 8080 because there's fewer portions of the screen it would have to update each frame. Naturally if you add a coprocessor or even use the graphics port to completely overlay the screen it's doable. However, it feels more retrohackery to have the existing 8080 inside the VT100 do the game loop.

Not sure if I'm horrified or delighted. But in a good way!