Stunt car racer for super cpu

[Jbizzel]

A guy created a mod for the c64 version to play on fast CPUs...


https://csdb.dk/release/index.php?id=230122


Would it be possible to mod a version for the spectrum in the same way, for use on the spectrum next and other systems with fast CPUs?

This is an incredibly advanced game for it's time, and when you see it running at 50fps - just wow!

I tried it original game as faster speeds on my NGO but it becomes hard to control, so I think some form of mod could make this game amazing on faster hardware!

[Jbizzel]

Buttery smooth

[Lee Bee]

I'm all in favour of upgrading the Speccy's CPU. As far as I'm concerned, it's the machine's only significant weak point that could do with "fixing".

Generally, I'm not in favour of "upgrading" classic hardware, as you can no longer really call it a "Spectrum". However, I would exclude a CPU upgrade from this, because the machine is doing exactly the same thing only faster. To use an analogy, it's like if I'm really tired and I eat a meal and get some energy, I'm still "me" - arguably, I'm even more "me" when I'm not lagging.

[catmeows]

Commodore's SuperCpu is 65816 clocked up to 20MHz i.e. you will get clock x20, 16bit accumulator instead of 8bit and 24bit addresss space. Not like all this is needed to speed up old game.
On other side, we have Z80 at 7 or 14 MHz (I'm not sure if 28MHz is a thing, last time I was interested in super spectrums, informations about 28MHz were little bit confusing).
Which leaves us with clock x4 (or perhaps x8), plus multiplication and division instructions for Z80N.

According description in video, the modder increased fps seven times and increased view distance.
Imho, you could get proportional improvement i.e. speed up game 4x or maybe 8x times but there is no super spectrum clocked at 3.5*20=90Mhz so I'm not sure whether it is possible to get 50fps and increase view distance at the same time.

[Seven.FFF]

spectrum next and other systems with fast CPUs?

I'm not sure if 28MHz is a thing, last time I was interested in super spectrums, informations about 28MHz were little bit confusing).

The Next has 3.5, 7, 14 and 28MHz. It's as simple as pressing NMI+8 to toggle between the four speeds while you're running the game. No game mods are needed. You can also select the speed you want it to run as on the TAP/TZX/Z80/SNA loader menu (and it remembers it for next time). You can also press NMI and fiddle with speeds and other settings on the fly in the NMI menu (an enhanced multiface) in the middle of running any game.

Of course running at a higher speed has little effect if the game is coded with a HALT every frame to sync screen drawing to the interrupt. When you run at higher speeds you have the same number of frames per second, but more T-states per frame. So a HALT still waits for the next frame and just burns more Ts waiting for it. Games like that would require some redesign.

But the slow ones are usually the one which aren't synced. They tend have a massive screen updating workload and they just plough through it as fast as possible. Classic offenders like Outrun and Driller are very playable at 14MHz. 28MHz is too fast for those.

[Jbizzel]

The game runs smoothly at a higher speed on the next, but becomes uncontrollable.

Same with driller etc.

Mods are needed!

[Seven.FFF]

Mods are needed!

So yes, obviously it's possible to do any mod at all on any Speccy or Next game. What did you have in mind? Just design it, then code it

I'm not trying to be flippant, but at 14MHz I'm able to get about halfway through Outrun stage 3 most times using the keyboard, which is the same as I can do in the standup arcade version (we have one in a local restaurant, which pleased me no end).

You could make it skip processing left/right input every other frame, or some mathematical ratio that pleased your taste, I suppose.

I agree Driller is a bit uncontrollable. For that I'd prefer to see a key repeat delay rather than simple skipping of input processing. What do you think?

[SaNchez]

Simply increasing the processor frequency where it was not foreseen in advance leads to deterioration of control. If the game logic is mixed with image output, it will be easier to rewrite such a game from scratch than to adapt it ¯\_(ツ)_/¯

[Jbizzel]

wow the super c64 version is so playable - I actually won a race for the first time ever. Its so playable!

[Lethargeek]

Commodore's SuperCpu is 65816 clocked up to 20MHz i.e. you will get clock x20, 16bit accumulator instead of 8bit and 24bit addresss space. Not like all this is needed to speed up old game.
On other side, we have Z80 at 7 or 14 MHz (I'm not sure if 28MHz is a thing, last time I was interested in super spectrums, informations about 28MHz were little bit confusing).
Which leaves us with clock x4 (or perhaps x8), plus multiplication and division instructions for Z80N.

currently in the Next wiki:

selectable speeds of 3.5 MHz, 7 MHz, 14 MHz or 28 MHz with wait states.

Obsolete info for core 2.x (limitation was lifted in core 3.0): the visible Layer 2 will cause the slow down of CPU to 7MHz.

The zxnDMA operates at the same speed as the CPU, that is 3.5MHz, 7MHz, 14MHz or 28Mhz. This is a contended clock that is modified by the ULA and the auto-slowdown by Layer2. Auto-slowdown occurs without user intervention if speed exceeds 7Mhz and the active Layer2 display is being generated (higher speed operation resumes when the active Layer2 display is not generated).

so i guess it still drops down to 7mhz, just not for the whole frame now
basically, a heavier version of original ZX contention (in addition to)
giving effective ~15-20mhz depending on the Layer2 size
(and much closer to 28mhz when it's disabled)

[SaNchez]

Not to engage in speculations, it is enough to write a small test, run it on a real Next and see that one interrupt takes about 450K clock cycles, i.e. its effective frequency is about 22.5 MHz on the current firmware version.
ZX Spectrum Next is really a constantly evolving computer, so unlike many other systems, its capabilities and performance grow as new firmware versions are released.

[R-Tape]

@Lethargeek and @SaNchez we don't want this thread to turn into another argument between you two. I'll be deleting (more) posts if it continues. You'd be better ignoring each other.

[catmeows]

One thing that could be fun is to rewrite Freescape to be cpu speed agnostic and attach data from various games. At least, there is not only sixtet of original games but also about ten or so homebrew games authored in 3D Construction Kit.

[Pegaz]

This new supercpu c64 version of Stunt Car Racer is totally awesome and extremely addictive !
I played the Spectrum version on a ZX Uno at 28Mhz, but the animation is nowhere near as fluid.
Also, I tried it on SpecEmu with a 50 Mhz cpu speed and even then, the smoothness was not comparable, but it did become more playable.
Stunt Car Racer is btw, one of my favorite C64 games, which I played for years and along with Indy 500 (Amiga), are the best racing games ever.

[Jbizzel]

I mean its amazing. better than the 16bit versions too. Maybe the BEST version of the game?

It really lets Geoff Crammond's amazing programming shine. I never noticed how much physics is acting on the rival car. Its so much fun just to get close and ride behind it, and watch. Its so cool.

I feel like this might be possible on an accelerated spectrum, but far beyond anything I could do sadly.

[Pegaz]

I mean its amazing. better than the 16bit versions too. Maybe the BEST version of the game?

It really lets Geoff Crammond's amazing programming shine. I never noticed how much physics is acting on the rival car. Its so much fun just to get close and ride behind it, and watch. Its so cool.

I feel like this might be possible on an accelerated spectrum, but far beyond anything I could do sadly.

This is definitely the best version of the game and the only one that can come close is the BBC Master port from 2019.
Also, there are several other good games that take advantage of super cpu expansion, for example the excellent Protovision shooter Metal Dust, several racing/flight sim games, as well as freescape titles like Driller, Darkside, Total Eclipse, Castle Master...
I also tried Last Ninja 2, every screen is displayed instantly...and here is an example of what Wolfenstein 3D looks like on C64 with super cpu.
This is the full 16 color version, which looks very nice, there is also a 4 color version, with buttery smooth animation.

[ANDREWRYALS]

Got to admit this piece of hardware looks pretty tasty.