adventures in II video

[Osgeld]

a picture is worth a thousand words, so here is what I am getting out of my iic (keeping in mind I am using a 20mhz digital storage scope from kenwood that defaults at a date of jan 1 1987)

Apple video is shorter than standard (longer front & back porches) because it is designed to be in the visible part of a TV screen, whereas broadcast video is normally overscanned (extends past the visible area on both sides).

that I get and quite clearly can see the porches are 2-3x the normal time, their timing is not critical, but the short total time per line is throwing the "loose standard" out of whack for brand spankin new tv's (the II's output is loosing nearly 3ms every frame)

meanwhile my thoughts against the ntsc colorburst is to simply bypass it during its time, though some form of pass through dongle, giving better 80 col text, maybe... we will see how my half page idea works out

 

[H3NRY]

Guess I ought to hang a scope on one of my Apples to see how it compares to your IIc. Filtering out color burst isn't going to do anything to boost the bandwidth of your TV set. A color TV displaying a B&W signal has no better response than it does in color, except that the text isn't tinted with false colors. I hacked into one of my color monitors to remove the 3.58 MHz trap and delay line in the luminance circuit, which did improve sharpness at the expense of some color crawl and fringing, but 80 columns is still pretty hard to read. If you have a II or II+, it's fairly easy to activate the color killer circuit permanently. I thought the IIc had a color killer like the other Apple IIs, in which case it doesn't put out color burst in text mode, only in graphics. The first 100 or so Apple IIs lacked the color killer circuit, and it was a common user hack to add it, or Apple would exchange motherboards.

Other experiments I intend to try when I have some tuits:

Will your LCD TV or monitor display Apple II text? Graphics? What brand & model is it?

Will your DV camera accept a video feed?

Can you video tape off your monitor screen? Is it best to use a solid state camera or one with a pickup tube? Will solid state pickups show bars rolling thru the screen? There are some demos I'd like to post on the web, but since they require peripheral cards, they can't be emulated. I'll need to shoot the screen.

My to-do list is pretty long at the moment, and these are low priority.

 

[Osgeld]

thought the IIc had a color killer like the other Apple IIs, in which case it doesn't put out color burst in text mode, only in graphics. The first 100 or so Apple IIs lacked the color killer circuit, and it was a common user hack to add it, or Apple would exchange motherboards.

yes after looking into it it does have a color killer, and it is functional, 80 col is horrid to read oh well, but interesing note, its quite clear when my scope probe is on it AND the voltage levels on the display data are just a bit high, maybe that is flippin the tv out, I dunno

Will your LCD TV or monitor display Apple II text? Graphics? What brand & model is it?

That is sorta my question too, although it does not directly effect me as all the tv devices at my house work fine with the //c

Will your DV camera accept a video feed?

I beleive that this will run into the same pitfalls as the super new digital lcd type systems, where the difference in timing will cause issues

Can you video tape off your monitor screen? Is it best to use a solid state camera or one with a pickup tube? Will solid state pickups show bars rolling thru the screen? There are some demos I'd like to post on the web, but since they require peripheral cards, they can't be emulated. I'll need to shoot the screen.

when I was a kid I used to make goofy movies with my friends, we always just jacked the //e into the back of the vcr and it always came out crystal, but only on the tape when played back, on the tv though the vcr it looked like low rez clown vomit

 

[H3NRY]

Tried a couple of things tonight.

Apple Blue & White Studio LCD: Will display Apple //e color graphics as composite video.

Will not display text, but then Apple says it won't display monochrome video, so no surprise.

Will not display either text or graphics as RGB at 15.75KHz.

Magnavox 15" LCD TV model 15MF400T/37: Displays //e text and graphics as composite video. Not bad, actually better than some CRTs.

RGB via the VGA connector doesn't work. (I have a RamWorks card with RGB adapter in my //e.) Modern monitors don't seem to sync on CGA RGB video (15.7 KHZ H sweep) like the early ones did.

 

[Anonymous Freak]

Apple Blue & White Studio LCD: Will display Apple //e color graphics as composite video. Will not display text, but then Apple says it won't display monochrome video, so no surprise.

Will not display either text or graphics as RGB at 15.75KHz.

Yeah, I wish there was a way to force the II-series into color composite mode no matter what. I'd like to use my B&W display for all my computers, including my A2s.

 

[H3NRY]

Which Apple II do you have? It's easy to defeat the color killer on a II or II+, and I bet it can be done on a //e or //c as well. Bear in mind, text will have purple & green tinges, and 80 col will be illegible. I'll dig out the Apple II schematic and tell you which pin(s) of which chip need to be lifted. Since the //e and //c may not have socketed chips, they are a bit harder to modify.

 

[Osgeld]

its mainly switched by the 1 and only transistor on the IIc, might be easier to deal with

and yea I have not seen a computer monitor in a long time that will accept ntsc rgb, I have one but its a rgb monitor that happens to accept ttl and vga also heh but its a thousand years old (like first model nec multisync)

unfortunately the active video time is just too long, at 31.7 us, 31.7us is also a vga line but that includes the active video (~25us) and porches and sync

so while it might be easy to overlay the signal on vga timing its going to be cut off on both ends (bummer)