Super Cars II (Atari ST) - finally cracking how the graphics and tracks work

[exxos]

That is great work. I'm looking forward to seeing how smooth it is.

Yeah it's nice. But also have to remember it still is a bit jerky simply down to the low resolution.

Are you going to keep the SFX the same as the original ST version? Using the YM2149? Then you can use the STe DMA sound to stream your new music (stereo WAV data) from the HDD

For the moment i dont have any plans to change the SFX. I think it would be time consuming and I'm not trying to spend huge amounts of time on it all at the moment.

Due to the DMA volume issues in the STe analog audio mixer (which mixes the YM2149 and LMC1992 together) you might need two recordings..

Assume it's this? https://www.exxosforum.co.uk/atari/last ... /index.htm
Near the bottom of the page.

[exxos]

Super Cars II STE: two player mode, old and new

A quick look at how two player mode has changed in the STE version. Both screenshots are from the same race, at the same moment, with the same game logic running, so the cars and weapons are all in the same places. Only the way it is shown has changed.

Original

SC2ORIG2P.PNG (41.12 KiB) Viewed 58 times

STE version

SC2STE2P.PNG (51.42 KiB) Viewed 58 times

What is different

• The original puts the two players side by side, each with a view 152 pixels wide and 148 high, with both panels across the bottom of the screen.
• The STE version puts them one above the other, each with a view the full 320 pixels wide and 98 high, with a thin black line between them.
• The panels have moved down into the opened bottom border, so they no longer take any of the screen away from the track.
• Each player now sees about 39% more track than before. You see further to the sides and a bit less up and down, so there is some trade-off, but there is more track on screen overall.
• The panels have been squashed onto fewer lines, with POS and LAPS sitting next to their figures, and the lettering is red for player one and green for player two so it is easy to tell who is who at a glance.

Why the change

• The STE version keeps the whole track in memory as one big picture and uses the STE's hardware scrolling to move the view around it. That is what lets it run at 50 frames a second instead of the original's 17.
• Hardware scrolling works on whole screen lines. Each line of the display can only start from one place in memory, so two different views side by side on the same lines is not something it can do. The original gets away with it by redrawing each half itself, which is a big part of why it runs at a third of the speed.
• Top and bottom works perfectly with it. Part way down the screen the video address is simply changed to point at the second player's part of the track, so both views scroll by hardware with no copying at all.
• Both views look into the same track picture, so a car only has to be drawn once even when both players can see it, which keeps the cost of two player mode down.

Same race, same cars, twice the width and three times the frame rate. Not bad for an old wooden panel.

[alexh]

Due to the DMA volume issues in the STe analog audio mixer (which mixes the YM2149 and LMC1992 together) you might need two recordings..

Assume it's this? https://www.exxosforum.co.uk/atari/last ... /index.htm

I don't remember the exact details but a normal STe the YM2149 is perceived to be a much higher volume than the DMA which if you use them both at the same time results in very quiet DMA sound and loud YM2149. This modification fixes this, results in something closer to a 50:50 volume mix (or at least I think that is what it did?)

I *think* early STe enhanced game developers of the time had a SW fix of adjusting the volume of the YM2149 outputs down and pre-amplifying the samples being played by the DMA. It is a fudge and I *think* can introduce distortion.

If you were going to mix YM2149 and DMA sound and you didn't want the SFX to overpower the music you might need to do the same thing? But it might sound wrong to those who have applied the HW fix?

I don't really know for sure. Certainly nothing to worry about for a while until you're fine polishing it

[exxos]

Yeah it's a problem. Theres modified and unmodified STE. Plus I'm questioning if doing the ST version is worth the trouble now. The ST could support larger tracks but it be very limited over the STe version. It would have to use the original game engine and it would probably still need more ram which a lot of machines probably only have 1MB.. Or less.

There is another problems of if the bottom border gets cut off on some monitors or upscales etc It's turning into to many combinations of stuff. It's same with the music, some may prefer the original chip and some may like the new music. Options can be done but I really need to be careful it doesn't start turning into a huge time sink in trying to do all the combinations.

Claude thinks the original game engine works on 512KB and 1MB.. But the pre-shifting is done at 2px or 4px depending on RAM. It's unproven. But if someone was so inclined to test and see if the scrolling looks smoother on a 1MB machine vs 512k..

[exxos]

DMA hard drive sound playback testing

Steem__00007.png (39.87 KiB) Viewed 25 times

Shame the STE only has 8bit sound, gets a bit hissy when the track is quiet. I guess i'll have to do 16bit STE system next

[exxos]

There's a bug that the main music starts on the super cars logo screen, then music restarts on the main title screen (with the car) you can't notice it on chip music, but playing sampled sound you hear it.. so they had a bug in there nobody ever noticed !

[JezC]

Shame the STE only has 8bit sound, gets a bit hissy when the track is quiet. I guess i'll have to do 16bit STE system next

That would be a great next project