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an old Atari ST demo running on the Jaguar


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with source code available :




A total conversion of the ST CONNEXION Demo - Let's Do The Twist Again - to the Atari Jaguar

original credits:
Coding: Alien
Graphics: Krazy Rex
Music: Celtics

using LSP by Arnaud Carré : https://github.com/arnaud-carre/LSPlayer ported to Atari Jaguar

complete source of this demo is available at https://github.com/ericde45/mega_JAG

Thanks to CyranoJ, Dilinger, Zerosquare, SCPCD, Fadest, 42bs for technical support and good advices

Thanks to Dyno & WAB.COM for the graphics assets and scrolltext.
Curves are coming directly from the ST

No 68000 !
No Blitter !
GPU & DSP only.

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The YouTube link looks cool, but I've tried this on three different Jaguars connected to three different displays now with four different Skunkboards and a GameDrive, both the ABS and .j64 ROM. Doesn't work. I see the intro screens, then it just goes black. On one system, I get the music. On the rest, just silence. Finally, I tried switching to 50Hz on my system that supports this, and on the 2nd try it worked there. Seems to be an NTSC/PAL thing. NTSC support plz! ;-)

Edited by cubanismo
Tried Game Drive and 50Hz too now.
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I think it's more subtle than that. @DEATH reported elsewhere that it did run fine on his Jaguar in NTSC mode.


I have mixed results:

- the ABS version (uploaded with BJL) crashes at PC=0x401D with 68K exception 3

- I have tested the ROM version in both PAL and NTSC mode, both with the normal boot ROM and with the BJL ROM. Sometimes it works fine, sometimes the title screen is OK but the screen turns black when the demo starts, sometimes I only get a black screen. Sounds appears to work in all cases.


I think it's either uninitialized RAM or uninitialized video registers.

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regarding 0x401D error, difficult to know what's going on as code starts at $4000 and $401d is not an instruction step

does the BJL needs some specific initializations ?

BSS RAM is cleared at start. stack also and OL areas also

i think i have issues with the fact that i have video inits + object list for first part and another video init + another OL for second part.

but currently as i only have 50 HZ jaguar, it is difficult to test. under emulators this is fine. ( at least on my PC :) )

004000: 23FC0007000700F0210C      move     [#F0210C], #70007
00400A: 23FC0007000700F1A10C      move     [#F1A10C], #70007
004014: 2E7C001FFFFC              movea    a7, #1FFFFC
00401A: 33FC06C700F00028          move     [#F00028].w, #6C7
004022: 33FC010000F14000          move     [#F14000].w, #100
00402A: 41F900053D40              lea      a0, [#53D40]
004030: 43F900063768              lea      a1, [#63768]
004036: 7000                      moveq    d0, #0
004038: 10C0                      move     [a0+].b, d0.b
00403A: B3C8                      cmpa     a1, a0
00403C: 66FA                      bne      #4038
00403E: 41F9001FFF98              lea      a0, [#1FFF98]
004044: 43F9001FFFFC              lea      a1, [#1FFFFC]
00404A: 7000                      moveq    d0, #0
00404C: 10C0                      move     [a0+].b, d0.b
00404E: B3C8                      cmpa     a1, a0
004050: 66FA                      bne      #404C
004052: 41F9001E0C00              lea      a0, [#1E0C00]
004058: 43F900200000              lea      a1, [#200000]
00405E: 7000                      moveq    d0, #0
004060: 10C0                      move     [a0+].b, d0.b
004062: B3C8                      cmpa     a1, a0
004064: 66FA                      bne      #4060
004066: 61000450                  bsr      #44B8
00406A: 610007C6                  bsr      #4832
00406E: 7000                      moveq    d0, #0
004070: 303900F14002              move     d0.w, [#F14002].w
004076: 23FC0195CA6C00053D40      move     [#53D40], #195CA6C
004080: 23FC0006572A00053D44      move     [#53D44], #6572A
00408A: 08000004                  btst     d0, #4
00408E: 6714                      beq      #40A4
004090: 23FC0195BEBA00053D40      move     [#53D40], #195BEBA

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updated :)


so it should be better

conclusions :

- i emptied the object lists at start with 0.l 4.l, instead of zeros. better filled with stop :)

- i added an object list for the introduction, as it seems better to avoid modifying an object list while it is used ...

- i removed move #$2700,sr, seems to be ugly in Jaguar world.


thanks a lot for all your tests



Edited by Ericde45
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  • 2 weeks later...

New version works on my US NTSC Jaguar as well now, all three files!

Did a (full scrolltext) video of this:




Btw. the first time here that the YT-video looks better than the source video I used for uploading! That has the usual "not quite in sync" stuttering, which were much better if not almost gone on YT! ?

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Yep, it's quite versatile as it also has (apart from HDMI) DVI, VGA via DVI adapter and S-Video/Composite/Stereo adapter.

For sound I usually use the Stereo line-in instead of HDMI, as it sometimes gives better results, e.g. Falcon and STE with their direct line out connectors.

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  • 6 months later...
  • 4 weeks later...
36 minutes ago, Ericde45 said:

i don't see what you mean by tremblement ? is that the name of an effect in the mad max tune ?


and this very old TNT demo would be quite easy on Jaguar.

The German word is "Schwebung". IIRC if two (or more) tones are close to each other, you get the rising/falling of volume (interference).

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