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manopac

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    videopac g7400 c7420 character memory locations

    in Odyssey 2 / Videopac

    Posted

    they are not 🙂 thats why you cant find them in ram ...

     

    seteg is actually a command in the G7400 Basic (16KB, written in Z80 code) that instructs the cart stuck into the G7400 (2 KB, written in 8048h code) to redefine a character on the EF9340+EF9341 chips (special chips in the G7400 not present in the G7000, that were also used in various teletext systems) - so no simple poke to set the characters 🙂 you could disassemble the C7420 Rom Source to see what exactly seteg is doing and it might be possible to write a machine language program in Z80 code you could poke into memory and run - but I doubt it would give you a speed advantage over seteg ... 

     

    also - not really worth scanning the memory from -32767 to 32767 - the C7420 has only 16KB of ram 🙂

    • Like 1

    Getting Started Making Games

    in Odyssey 2 / Videopac

    Posted

    10 hours ago, atari2600land said:

    In O2EM, press F4. In that, type in (save grid thegrid.txt dbhex) to generate a text file containing the grid's data. You can get back to the game by entering "q".

    I implemented this debugger command specifically for the purpose of saving the grid after using my grideditor :D

    (which can be found along with the other tools I wrote here btw (then you also see what keys are supported in gridedit)):

    http://www.guttenbrunner.com/videopac/

    Bad Apple for the Odyssey 2?

    in Odyssey 2 / Videopac

    Posted

    Its nothing that can be done in Software only - again: Software only allows a max 12 KByte, for everything else hardware bankswitching is needed that can have different forms, ones of which is the one Soeren implemented in his MegaCART, others are what Videopac 31, 40, 55, 58, 59, 60 doing ... 

    so if you REALLY want to get around the 12 KB Limit, you can - I wouldnt advise it though, as you would have to copy an existing bankswitching scheme (to use it in an emulator where it is supported), build your hardware to try it out properly and also find someone willing to manufacture carts from it then ...

    Bad Apple for the Odyssey 2?

    in Odyssey 2 / Videopac

    Posted

    Well - they just didn't think far enough :D from the initial point it made sense - the O2 had much better capabilities than the Atari 2600 in terms of elements it could display at once - games like Munchkin made Pac Man on the A2600 look really bad ... compared to the first Atari 2600 games, the O2 games just looked and played better ... but the Atari 2600 programmers soon found ways to get past the few "player/missiles" and other elements that was the "base set" of what the A2600 could do - so games on the A2600 got better really quickly (especially when Activision entered the scene ...), while O2 games stayed what they were (with few exceptions like Killer Bees) - and the fixed character set in the end also didnt really help the system as games started to look "the same" (with the guy walking always being taken from the characters and thus always being the same character in most games ...)    (just IMHO)

    Bad Apple for the Odyssey 2?

    in Odyssey 2 / Videopac

    Posted · Edited by manopac

    On 3/3/2023 at 4:09 PM, atari2600land said:

    Bankswitching doesn't go very far on the Odyssey 2 I'm afraid. The biggest game you can possibly get on Odyssey 2 is 16k, and that's with bankswitching.

    so - this is not true 🙂 without any extra hardware the total an O2 game would be able to access is 12 KByte (4 banks, 3Kbyte per bank, 1Kbyte is "reserved" by the ROM which is hardwired into the Cartridge space), but even some original games for the Videopac+ use 16K using extra hardware for bankswitching on the cart (59+, 60+) - and one concept for doing this is what Soeren Gust was designing with the "MegaCART" long ago (so long ago that the webpage is not available anymore other than in the internet archive ...):

    http://web.archive.org/web/20130613131556/http://soeren.informationstheater.de/g7000/megacart.html

    with this you would be able to get 1 MByte for the Odyssey2 (not using a Voice, thats the only restriction ...)

     

    The bad apple demo would not work for another reason - the O2 does not support a "Bitmap" in the classical sense ... thus not allowing you to show an "image" built of of "pixels" ...

    (the Atari 2600 doesn't have that either, but here comes a design flaw of the O2 - the processor and the video beam are not in sync ... so the so called "racing the beam" that allows you to exactly switch colors always on the same position at the screen at the Atari 2600 is not possible on the O2 ... thus limiting programmers to basically what the hardware was intended to do without being able to do proper "tricks" ...)

     

    So in theory to do the bad apple demo on the O2 you would need to build up each frame using just the standard elements that the system provides:

    - built in characters (or parts of them) (12 single characters, 4 "blocks" of 4 characters)   (from the top of my head, not 100% sure the numbers are correct)

    - sprites (4)

    - the grid

    - background color

    if you manage to build up each frame from those elements (maybe with switching some elements at the end of the raster line) then it could be possible ... but the effort is enourmous ... and yes, you would need the "MegaCART" for it, as the code will look different for every frame of the demo, depending on how many frames you need and how complex each frame is, lots of code is needed for that ...

     

    it might be possible to do on the Videopac+ (the never released Odyssey 3 in the US), as you can define bitmaps there (see background images for Videopac+ games) - not sure you can do it fast enough to show a different image every frame though - but worth a try 🙂

    • Like 3

    Emulating chess C7010 module

    in Odyssey 2 / Videopac

    Posted

    On 2/24/2023 at 11:15 PM, pboland said:

    How much in the way of capability (computer power) does this add to the G7000? Does this make the G7000 similar in capability to the G7400? Obviously it wouldn't be compatible with the G7400 since the C7010 is Z80 based, but I'm wondering does the C7010 computer module add signification capabilities that more detailed games could be made (other than chess) with it.  I don't know, maybe I'm thinking too hard about this...🤔

     

    It's still really cool!

     

    it adds a whole computer to the G7000 basically - got nothing to do with what the G7400 does (as thats basically a better (additional) graphics chip, but the same processor 

     

    the C7010 (and the C7420) both have a Z80 processor inside, additional ROM (for running the Z80) and additional RAM - both communicate with the "original" machine by exchanging data through the cartridge port telling the G7000/G7400 what to display on screen - you are still limited in gfx what the G7000/G7400 can (not) do

     

    the current SD card solution cant emulate it, but @wilco2009 did an emulator for both the C7010 and C7420 already as described here:

     

    now we just need to keep our fingers crossed that he decides to build and sell them ;-)

     

     

     

    videopac.nl forums closing

    in Odyssey 2 / Videopac

    Posted

    On 10/12/2022 at 7:22 PM, Mikebloke said:

    I lurk the forums occasionally, I think for me the priority would be : securing any downloads people have made available and anything relating to programming for the system. I started some tests myself to try it out and I think that forum has a few things that helped.

     

    It sucks to hear its on the way out, even though I'm not a member, Google sends me there on a regular basis. 

    best time to sign up for it now ;-)

    FloB - teaser

    in Atari 8-Bit Computers

    Posted

    On 6/27/2021 at 1:48 AM, mariusz-buk said:

     

    1. Beeblebrox
    2. invisible kid
    3. Philsan
    4. Sub(Function(:))
    5. Spancho
    6. CAVOKER
    7. 8bitguy1
    8. Roydea6
    9. pps
    10. CharlieChaplin
    11. Lord Thag
    12. Wilheim
    13. Dinadan67
    14. TrekMD
    15. martinez
    16. Ndary
    17. Oldyoldson
    18. Hurrican

    19. a6502

    20. Allan
    21. hasanc

    22. janzh

    23. electrohaze

    24. Gunstar

    25. Tigerduck

    26. mariusz-buk

    27. manopac

    • Thanks 1

    Ultimate Cart - Users thread

    in Atari 8-Bit Computers

    Posted

    just got my Ultimate out of storage after not using it for about a year - and it doesn't work anymore ... I checked the SD Card, it still reads ok on my computer, any ideas what I could do ? I tried the cart in an XEGS and a 600 XL - both show the same behaviour as if no cart is inserted, while the cart itself has a red blinking light ... thanks for any help !!

    FT: Atari 2600 Homevision Cartridges / Looking for Atari 8bit and other

    in Buy, Sell, and Trade

    Posted

    opening a new topic, as I can't change the title of the old one and it's no longer valid ...

     

    some of you may remember, that I offered some of my Atari 2600 Homevision Cartridges up for trade - they are boxed, no manuals, picture below.

     

    I am looking mainly for rare Atari 8bit software/hardware, e.g.:

    Alleycat, Quasimodo (Synapse)

    The Spy strikes back (Penguin Software)

    The Abandoned Scrolls (Access)

    Plundered Hearts (Infocom)

    Suspended, Starcross Folios (Infocom)

    most Datamost titles

    some Datasoft Titles (Lost Tomb,

    1200XL boxed

    810 Floppy boxed (preferably PAL)

     

    as well as some Atari 8bit Homebrews, namely:

    Line Runner

    Yoomp!

    Isora & Loops DX

     

     

    Creativision game:

    Stone Age

     

    rarer Atari Jaguar games
    Battlesphere, Air Cars

     

    Vectrex:

    3D Imager+games, Pole Position, Polar Rescue

     

    I haven't had much luck looking for any of the titles in a trade, so I might also entertain cash offers, but I would prefer trading ...

     

    homevision_1.jpg

    homevision_2.jpg

     

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