ClausB

You're welcome. So, you bought the whole thing for $11 and you're selling part of it for $35? Nice.

Here's the last section of the article - about the RAMdisk software. Just noticed that I never posted the whole article, so here it is.

The Whiztronics is a copy of my 1985 upgrade posted here: http://www.atariage.com/forums/index.php?s...t&p=1481893 Maybe this schematic can help you undo the mod. You can definitely leave the DRAM chips in there. Put the 74LS158 chip back into the U27 socket. If the upgrade was done properly, no traces would have been cut. You should reconnect the 3K ohm resistor at R32 (between +5V and pin 1 of the DRAMs). Good luck.

Looks very nice! In ACE-80 I sped up scrolling by rearranging the display list instead of moving GR.8 data around. Feel free to borrow the technique or any posted code. See: http://www.atariage.com/forums/index.php?s...t&p=1496090

Nice. RLL compression or something more fancy?

Very nice! It runs OK here in Atari++ 1.30 in both NTSC and PAL modes. Merry Christmas!

Hmm,maybe you can correct this bug ?!? Meaning in the *.OBJ files and maybe also in the *.BAS file if the buggy snow DLI routine is in there ?!? It should be very easy then to add any other Gr. 15 Koala or Micropainter picture and thus to create some more demos in this style... OK, I fixed it in 2 of the .OBJ files (FROSTY and CHRSTREE). I also changed SNOWFALL.BAS but did not test it. Would you test it? XMASCRO2.zip

Interesting possibilities here: http://www.parallax.com/tabid/708/Default.aspx

LOL! I especially like the Hoseheads. Take off, eh? (Funny 'cause I just got back from business in Quebec - but they don't say "eh" there.) Looks like someone took my snow DLI routine and added a utility to change the bitmap and text. He took an early version, though, which has poor timing in switching the background color at the bottom.

Good work! Thanks for posting it.

Happy Holidays to all my new friends at AtariAge! XMASTREE.zip XMASTRE2.zip

So much for that theory! How'bout this one: luma bits turn off faster than they turn on? The GTIA luma outputs appear to be open-collector because they have pull-up resistors, so this theory makes sense.

Notice that the worst artifact is between luma values 7 and 8, where all 4 luma bits change. Apparently the lower bits change faster than the upper bits, so the luma goes darker before it gets lighter. The effect is less noticable between lumas 3 and 4 and between 11 and 12, where only 3 bits change. To test this explanation, plot the bars in reverse order and see if the artifacts are light instead of dark.

This prototype is dated January, 1979 but has parts dated 1978. It also has the yellow-brown rainbow logo.

Wow! Very nice explanation without getting into the deep math of color subcarriers, phase encoding, frequency interleaving, and such. Really? I always thought that the chroma signal had 50% duty cycle, that is, the "chroma pixels" were 1/2 of a "color pixel", and that only the phase varied with hue.

Are tech specs available? Memory map, banking schemes, register definitions, etc.?

Why is that?

Good work! A much cleaner solution than building an adaptor circuit. I remember the MCM68764 from the mid-80's, when it cost about $40!

A challenge to you C64 fans: Port this (only 28 hacking days 'til Christmas): XMASTREE.zip

Thanks for that link. I had no idea that it was so widely distributed, even before the Internet.

I must apologize for posting something old. In the spirit of the original thread, here's a new variation. Can you spot the differences? XMASTRE2.zip

Never heard of it. This was done all by hand on my 400. I wrote a BASIC joystick drawing program to make the tree image in ANTIC mode E. The snowflakes are Missiles, sliced up by DLIs. The colored bulbs are Players showing (rather imperfectly) through holes in the tree Playfield. The init, DLI, VBI, and scrolling routines were coded with the Atari Assembler/Editor cart. Finally I pasted all the parts into a cassette boot file (had no disk drive back then).

Thanks. The only other decent demo I can recall is the Tron Recognizer wire-frame animation for the Axlon RAMDisk I posted here a few months ago (look left). I did a few pictures/intros for PDI when I worked for them. The ones I recall were Franglais, Mathwise, and Wordwise. I worked in a little computer shop in East Lansing and ran the tree on their demo 800 over the Christmas season. I recall playing a cassette with Alvin and the Chipmunks' Christmas music.

It's not new but here's one I did in 1981. It was inspired by Chris Crawford's article in BYTE for December, 1981, about DLIs. The article was one of a BYTE series that became the book De Re Atari. This is a zipped, bootable ATR. It also turns on the 410 Recorder so you can play your favorite Christmas music cassette! XMASTREE.zip

But here in Michigan we have another season between Summer and Winter. It's called FLL. That's FIRST Lego League competition season. Go Programmers! OK, FLL season ended tonight. And winter is definitely here, so I need to get busy with the experiments. Trouble is, I put away the Atari when we got kittens last month. Yeah, I know, excuses, excuses.