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ClausB

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Posts posted by ClausB

  3. Posted · Edited by ClausB

    this demo reminds me of an old Antic or Analog (?) demo-construction set

    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).

  4. Posted

    Claus, your christmas tree impressed me in old good times. Have you programmed more pictures/demos/intros like this one?

    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.

     

    Wow - that was one of my first BBS downloads at a glorious 300 baud back in 87. I never knew it let you play cassettes.

    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.

  6. Posted

    Summer's over...

    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.

  7. Posted

    Claus is going to help us fix this with his FRAM video hack. With a version designed for it, we might be able to do our own assignment and feed digital displays a tricked interlaced picture.

    I'm not sure we can make interlacing work, but I have an idea for generating 480p30 (480 progressive scan lines at 30 Hz). Though I don't know which display devices really support that mode.

  10. Posted · Edited by ClausB

    Can someone provide a one sentence description of the function for the following 5200 pinouts:

     

    04. R/W Early

    05. Enable E0-EF

    16. Audio In

    18. System Clock 01

     

    Like, why would Audio go in?

     

    Also, if someone could explain the explicit function of each of the Address Lines, numerically, that would be helpful. For instance, why aren't all of the address lines used, and why the jump from A11 to A14. I'm sure that this has something to do with the 5200 being limited to 16K, but what are the functions of each line?

     

    Also, are the Data Lines Big Endian or Little?

    04 is the "Read / not Write" signal from the CPU, undelayed (as opposed to "R/-W Late", delayed for DRAM timing, IIRC).

    05 is from the address decoder, signalling that the CPU is accessing an address in the range $E000 to $EFFF.

    16 is for the 2600 expansion unit's sound output, which goes through the 5200's audio circuit to the TV. There's also a video input for the 2600 expansion unit.

    18 is the CPU's 1.79 MHz clock phase 1.

     

    A11, combined with Enable E0-EF, decodes the address range $E000 to $E7FF, a block unused on the motherboard.

     

    A0 through A7 are the low 8 bits of the address bus, used to address within the $E000 to $E7FF block decoded above. You've got 256 bytes of space to add peripheral I/O or banked RAM or ROM.

     

    Why A14 is there is a complete mystery to me!

     

    Data line D7 is the high bit and D0 is the low bit.

     

    See also my article at http://www.videogames.org/html/5200Stuff/5200.notes.html and my posts in the 5200 threads.

  11. Posted

    It was suggested that Dual-Ported RAM could be contained on a 5200 cartridge connected to an Atari 8-Bit, allowing the A8 to be a development system for the 5200:

     

    "An adventuresome hacker can even bypass the EPROM

    by putting dual-port RAM on the cartridge board and

    downloading programs from the 400/800 development

    system into the 5200 for testing."

     

    http://www.videogames.org/html/5200Stuff/5200.notes.html

     

    The only reason you need dual port is if you want to change the data while the 5200 is running. Otherwise, you can simply switch the bus from one system to another.

     

    When I wrote that sentence 25 years ago, I envisioned something more like what Bryan said above, not a full-blown dual-port memory with real-time debugger. It was academic, though, and I never built any such thing. It's the kind of suggestion I liked to put at the end of an article, just to get readers' imaginations going. I don't know if anyone built one, but I've heard Atari had some such things in house.

  12. Posted

    Too bad about the ABBUC contest. I did not look at the other entries, but Bob's accelerator is too cool for last place. There was some lame excuse about the 1200XL being scarce in Europe, even though Bob's 1st post here about the upgrade says it applies to the 800XL as well!

     

    So ist das Leben.

  14. Posted

    Well, as a non-programmer I am not exactly sure what is page-flipping and err, which programs use it and which don`t. As far as I remember it e.g. has to do with loading several pictures into RAM and then doing an animation by page-fipping (showing the pics in a certain manner so that they appear as an animation).

    Yes, the BASIC program drew one frame in GR.6 mode, then changed the OS pointer to screen memory (and changed the RAMDisk bank), then drew the next frame in another 2K region, and so on. It also saved all the screens to disk. On playback, the assembly routine changed the display list pointer to screen memory (and the bank on every 8th frame) 15 times per second for animation.

  15. Posted

    If hue 15 is exactly in the middle, then the phase angle would be 360°/15 = 24°

    Both are true. :)

     

    You define that hue 15 = hue 14 + 24° = hue 1 - 24°

    I define that hue 15 = hue 14 + 24.8°/2 = hue 1 - 24.8°/2

     

    In both cases, hue 15 is in the middle between 1 and 14. :)

    Not quite right, because hue 15 - hue 14 is the same as hue 14 - hue 13 and as hue 13 - hue 12, etc. Therefore, hue 15 - hue 14 is much more than 24.8°/2.

  17. Posted

    Better than composite is a monitor with S-Video input, but you have to modify your 800XL slightly to use it. Search these forums for instructions. You also need to build or buy an Atari to S-Video cable.

     

    The old Commodore monitor used a precursor to S-Video and it looked great with an 800.

  19. Posted

    If you want, you can remove both old BASIC ROMs from your cartridge and put the XL BASIC ROM into either one of the sockets. Then you'll have the newer BASIC in your cart.

    So either ROM socket of the XL series takes a 27256 EPROM? That would mean you can put in any ROM instead of BASIC into the Atari memory $8000...$BFFF area and use OPTION to disable it.

    NO! The BASIC ROM has 24 pins - not 27256 compatible.

  20. Posted

    ... if I remove the BASIC chip altogether (U4) and then lift pin 18 of the MMU (U3) the 800XL boots up to self-test and I no longer need to hold down OPTION to load software.

    That works because pin 18 has a weak internal pull-up that keeps the -BE (BASIC Enable) signal high, or inactive. But it could pick up electrical noise and cause mysterious crashes.

     

    A better solution is to reconnect pin 18 and disconnect the signal at the other end, pin 11 of U23, the PIA. That way, R85 can pull the signal up strongly.

     

    You don't need to remove the BASIC ROM - it should never get selected. If you want, you can remove both old BASIC ROMs from your cartridge and put the XL BASIC ROM into either one of the sockets. Then you'll have the newer BASIC in your cart.

  23. Posted

    Don't forget the color delay pot. IIRC, it adjusts the spacing between hues. In the color wheel above, you have 360° of hue and the Atari has 15 hue levels. To space them uniformly around the wheel, the hues should be 24° apart.

     

    If the spacing is too big, you get repeated hues between the top end and low end. That appears to be the case with the emulators' hues shown above. There are repeated yellows, greens, and even oranges at the bottoms of the images.

     

    Was there ever a standard for adjusting those pots?

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