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Tennis, anyone?


glurk

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This wasn't supposed to work.  Back in January, I did a partial disassembly of Activision's "Tennis."  I couldn't figure it all out, so I quit on it and posted what I had finished in the 2600 forum.  And mostly forgot about it.

 

But recently, I had an idea.  What if instead of figuring it all out, I JUST took the disassembly I had and made it work on the 8bits by changing GRP0 to GRAFP0, COLUBK to COLBK, etc, etc etc...  To my great surprise, it actually worked.  A bit more work, and I added in some graphics for the playfield stuff, a sound routine, and my ubiquitous logo.  And it's all working pretty well.  Some minor issues, but I thought I'd get a demo out there.

 

This one balances things out for me, as I've now done 2 Steve Cartwright's. 2 David Crane's and 2 Alan Miller's...   I'll polish this one off at a later time, but for now:

 

tenny.bin

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39 minutes ago, glurk said:

I'm calling these the FINAL releases.  I can't find any bugs...  OPTION changes difficulty settings, although computer kicks my butt regardless... Same as the original version, LOL.  I may try, at a later time, to get this on the 5200.  NTSC and PAL for now.

 

Tennis - FINAL [NTSC].car 8.02 kB · 3 downloads

Tennis - FINAL [PAL].car 8.02 kB · 1 download

This is awesome!  Any chance someone could make an XEX version,  please....?  That way you can load it right off a SIO2SD.

 

 

Edited by ACML
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REALLY FINAL this time, I hope, LOL...  These fix a small graphics issue with out-of-bounds balls.  It was easy enough to fix, and makes it look better than having a glitch...

 

There will be no 5200 version, due to programming difficulties.  I could probably make it work, with much time and effort, but this game is not really worth taking up that much time on.  Not that I think I've done a bad port, I just don't think it's a particularly inspiring game...

 

EDIT: I goofed, I uploaded ones without the fix added.  I'll post them later, I'm in need of rest and getting sloppy...

 

Edited by glurk
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OK, now I got em...  Just a couple small fixes to finish this off.  Not much changed from the original Activision game on this one, black-webby net and a yellow ball (which is hard to even notice).   Some few other tiny unnoticeable things...

 

This was kind of an easy (accidental) port, it was an experiment that worked.  Turns out that the original 2600 kernel for this one was so "loose" (not cycle-counting precise, "tight") that it ported over to the 8bits and just worked.  I didn't have to do very much at all.

 

I could have gone crazy with this, and added more court lines, and texturified grass, blah, blah.  But that's never been my intent, and I suck at graphic art anyways.  But it's a nice little Tennis 'simulation' and the first Tennis game to use this perspective I think (read that somewhere...)  Fixed versions:

 

Tennis - FINAL [NTSC].car 

Tennis - FINAL [PAL].car

 

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I was already aware of those sprite issues.  But the data is at the same LSB offsets as the original, and I even tried a +1 / -1 bump to no avail.  I put it down to minor timing differences and left it at that, because it seems to have zero effect on gameplay.  It might be an easy fix, it might take weeks to track down, who knows.  I chose to just leave it...

 

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There are some other oddities with the sprites too. If you look at their rackets, they don't have the same shape, and sometimes appear square in the 800 version. Also, their extended arm should always look as seen in the 2600 screenshot above.

 

I had a look into the ROM, and the sprite data looks to be correct. So, it has to be something with how they're being rendered.

 

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Just FYI to all... I've located and fixed the sprite issues noted by @MrFish and @SpiceWare but I'm going to go over the code a bit more before I release the new ones.  It was a combination of issues.  For one thing on the 2600, all the TIA registers are zero-page but on the 8 bit, the ANTIC/GTIA registers are NOT.  So the stores take longer to GRAFP0 than to GRP0 for example.  So I sorted thru all that crap...  It does look better now, but must test a bit more before release.

 

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Sometimes it takes a while to get all the kinks out.  Probably a good thing that people point out these issues, keeps me on my toes.  I was probably going to let this one slip, but I've found and fixed the sprite problems, and now it's a better game and more like the original.  So, again:

 

Tennis - FINAL [NTSC].car

Tennis - FINAL [PAL].car

 

I still don't think I'll be able to do a 5200 version though.  I tried again, and it's just not working out at all...  Sorry about that.  This game is programmed in a whole different way than all the others I've done, it's basically a bare-metal port of the 2600 kernel.  And it was from scratch, in that I did the whole 2600 disassembly and conversion all on my own.  But it doesn't use any of the framework stuff I usually use, so it won't readily convert to 5200.

 

 

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  • 10 months later...
On 4/4/2022 at 5:32 AM, glurk said:

Sometimes it takes a while to get all the kinks out.  Probably a good thing that people point out these issues, keeps me on my toes.  I was probably going to let this one slip, but I've found and fixed the sprite problems, and now it's a better game and more like the original.  So, again:

 

Tennis - FINAL [NTSC].car 8.02 kB · 134 downloads

Tennis - FINAL [PAL].car 8.02 kB · 66 downloads

 

I still don't think I'll be able to do a 5200 version though.  I tried again, and it's just not working out at all...  Sorry about that.  This game is programmed in a whole different way than all the others I've done, it's basically a bare-metal port of the 2600 kernel.  And it was from scratch, in that I did the whole 2600 disassembly and conversion all on my own.  But it doesn't use any of the framework stuff I usually use, so it won't readily convert to 5200.

 

 

Love this, you have won the race against time and it's working nicely. I missed this earlier and just caught up today. Thank you

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On 4/4/2022 at 5:46 AM, Wrathchild said:

If you chuck the sources onto the DM thread for 5200 porting I added you to then we can take a look

Love this port.  Still would be greatly appreciative if someone could make this an XEX file so it could be loaded with a SIO2SD.

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