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Jump VCS


KevinMos3

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Jump VCS at retro-reload.com
I ran across this on youtube yesterday while browsing for "atari homebrew." I haven't heard of it before and found no mention of it when running a search on the forums, so I thought I'd share and show it some love. It's a very impressive use of bB and comes in at only 4Kb!

Now, I don't mean this as a complaint in any way, but I can't help but imagine what could be done with 8K or even 32K... AtariVox support, digitized music??? I digress. Downloads are available at the link above and it's supposed to get a cart release, but I don't know when.

https://www.youtube.com/watch?v=S1WNNTtHSX8

 

I really love this game and even though it already has an official label made for it, I slung together another one last night using some Canabalt artwork.

post-9364-0-42045200-1417488703_thumb.jpg post-9364-0-04518400-1417488717_thumb.jpg

 

And a mockup of a cart:

post-9364-0-71332400-1417488796_thumb.jpg

 

edit: Okay, so my initial search for Jump VCS didn't turn up anything for some reason, but a search for Brik did...

There's already a thread on this game started by Thomas. As seems to be the case a lot lately, I'm really late to the game, :lol: so sorry for the re-posting. I suppose the game deserves a double dose of attention anyway. :)

Edited by KevinMos3
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  • 3 months later...

Some questions i have to this game. ALBERT wrote here, that the game let the user choose between PAL and NTSC at startup.

 

Here the programer offers the roms: http://repixel8.com/games/jumpvcs

There is a PAL and a NTSC version and i recognized, that the scrolling in the PAL-rom is faster than in the NTSC-rom. I think this game plays best with the NTSC-speed. Seems like the programer wanted to adjust the speed of the game for PAL-consoles to the NTSC-speed and made the PAL-version to fast. And the difference can be recognized at once, its not only a little speed-difference, its obvious.

 

Now my questions:

 

(1) does anybody know, if there exist an updated PAL-Rom version of this game, where the speed is corrected and exactly like the NTSC-speed and not faster? Or exist a PAL60-version of the NTSC-rom, with adjusted colors, this would be the best?

 

(2) is the PAL/NTSC-switch at startup, also possible in this roms? Or is this only in the real cart (because roms are already available in PAL or NTSC)?

 

(3) and if this PAL/NTSC-switch is also possible in these roms, how can this be done in STELLA-Emulator? is it possible there, to set a rom to BW-color before starting it, to activate the PAL-mode?

 

(4) last question - when a user that has the real cart, switches between PAL and NTSC in this game, is then the speed-difference also that big, or was something updated later in the real cartridge-versions?

 

Maybe somebody can answer this. Thanks in advance.

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For (3), load the ROM, tab/Game Properties/Console/TV-Type = B & W, then reload the ROM (CTRL+R)

Thanks, this works. I knew that there is a properties-menue, where i can adjust how a rom will be started (Automatic/Pal/Ntsc/Secam and so on), but i didn`t knew, that i can also choose between "color and bw" in this menue. So STELLA is really great and also this game JumpVCS is great.

 

By the way. On my PAL-Atari2600 i started the NTSC-rom of JumpVCS yesterday (with the Harmony) and i don`t see a big color-difference. I played until Level-3 and it seems, that also the NTSC-rom of this game can be played on PAL-consoles without an adjusted color-palette. Also in later game-levels, it looks very similar, no matter if this NTSC-Rom is played on a NTSC- or a PAL-console. How can this be? But this is good, because the playability of the PAL-rom is not so good, it runs to fast.

Edited by AW127
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  • 2 weeks later...

Hi,

 

Just noticed this topic and thought I will clarify the AW127's questions around JumpVCS

 

Unfortunately due to the timing differences between PAL (50fps) and NTSC (60fps) and the fact the game scrolls horizontally in steps of 1 playfield pixel, it is impossible using an integer frameskip to exactly match the 20% difference in speeds between PAL and NTSC within the limitations of the 2600. However, the PAL version should only be slightly faster than the NTSC version and not anywhere near 20% faster.

 

I did design the game in such as way that the NTSC version will work without problems on a PAL console (i.e. PAL60) and vice versa, as I used colors that work on both formats. I guess the NTSC version would be the preferred version to run on PAL consoles, unless you have a TV that does not support NTSC or PAL60 in which case you would need to use the PAL version.

 

2) The roms that can be downloaded from http://repixel8.com/games/jumpvcs do not have PAL / NTSC switching capabilities built in, as they are the original 4K roms and the game left no space for this logic. Originally, it was planned to release these as 4K cartridges however, the 32K physical cartridges which will be available soon have bank switching abilities, which allows for both NTSC / PAL60 and PAL versions, plus the selection screen at startup, and an additional title screen with music. So in summary, the PAL / NTSC switching will only be available with a physical cartridge.

 

Hope this helps.

 

By the way, I should also mention that the additional space available in the upcoming Brik cartridge will be utilised with a special bonus game, Brik180 which works with joystick and paddles :) Also, the original version of Brik will have a non-flicker mode that can be enabled with the 2600's 'Select' switch.

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:idea: Instead of using an integer frame skip, you should use fractional math in such cases as mentioned in the Stella Programmer's Guide.

 

This requires just one RAM variable, where you add a constant value per frame. This constant value is different between NTSC and PAL. The PAL value is 6/5 (assuming 312 and 262 scan lines) of the NTSC value.

 

Example: Trigger event (e.g. scrolling) every 4th frame.

In NTSC, you add 64 (256/4). Whenever the variable overflows, you scroll. For PAL you add 76 (64*6/5), so the game will scroll every ~3.37 frames.

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Thanks for the suggestion.

 

I did take a look at this at the time, but unfortunately that would have pushed the game past the 4K limit. Towards the end I was fighting for every byte and in fact, some of the "features" of the game are a result of having to make compromises to make every single byte count. By the time it came to make the PAL version there were next to zero bytes free, so as a result the NTSC version scrolls every 4th frame and the PAL version every 3rd frame (rather than 3.37), which means the PAL version runs a little faster than it should. I hindsight, if I'd have known it would be released on a 32Kb cartridge I could have implemented this, along with other features that I had to leave out, but maybe these could be something for a future sequel :)

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