Game issues on Mame 0.232

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NeoMK
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Game issues on Mame 0.232

Post by NeoMK »

Evening All,

I’m currently expanding Pipmick’s BBC Micro package (for Coin-Ops Next 2). At its heart, it’s now running Mame 0.232.

Most games have been integrated just fine, but I’ve a few that either don’t work at all, or have a severe issue. I’m new to running beeb games under Mame, so perhaps these are well know issues.

1. Firetrack

Despite trying lot of different versions (both Electric Dreams and Superior) and different machines (B and Master), the game suffers from a severe scrolling, stuttering issue. One version even crashes completely.

Is there any known fixes for the scrolling problem?

2. Stunt Car Racer

This game appear to run fine until the point you start the actual race itself. At this point, the graphics appear corrupt, like zoomed in alternating colour blocks. You can still hear the sound, perhaps control the car but it’s pointless. Any known fixes?

3. Trickysoft Games

I’ve been working through an alphabetical list of games and was looking forward to testing ‘T’ with Richard’s games.(all labelled Trickysoft_ )
So, Carnival, Pac-Man and Asteroids all work fine.

However, Astro Blaster, Frogger, Phoenix and Scramble all exhibit the same type of graphical issues as Stunt Car Racer. (see pics enclosed)

Tricky - I think you have explained why Mame has perhaps a few issues with some of your games. I hope your suggestion can be taken up by the Mame developers to open up the rest of your game library for everyone to enjoy.
Also, when selecting 'bbcm' to emulate the Master and gain Sideways RAM, I did hear speech on Astro Blaster though the pitch was slightly sped up.

That’s is for now. Appreciate any advice.
Scramble in-game
Scramble in-game
Phoenix in-game
Phoenix in-game
Frogger in-game
Frogger in-game
AstroBlaster in-game
AstroBlaster in-game
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tricky
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Re: Game issues on Mame 0.232

Post by tricky »

Astro Blaster plays sampled speech at the beginning, but I don't think that MAME supports speech on the beeb, which is a shame as the speech chip simulation in beebem came from MAME!
Fire track does similar tricks to some of my games, so will require the same fixes. I don't remember what SCR does, but I thought it was basic screen residing.
I would love to see the basic Beeb fully supported, but I think our current MAME developer is concentrating on preservation and supporting all the rare machine variants and add-ons.
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kieranhj
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Re: Game issues on Mame 0.232

Post by kieranhj »

NeoMK wrote:
Mon Jul 19, 2021 11:31 pm
2. Stunt Car Racer

This game appear to run fine until the point you start the actual race itself. At this point, the graphics appear corrupt, like zoomed in alternating colour blocks. You can still hear the sound, perhaps control the car but it’s pointless. Any known fixes?
All of these issues look like problems with vertical rupture techniques, which is essentially reprogramming 6845 CRTC video chip registers at specific points on the display. If the 6845 implementation is not accurate and/or the 6522 interrupt timers are not accurate then it could easily result in the glitches that you describe.

For SCR specifically, the screen is ruptured three times such that the top damage bar is one fixed address, the central view is double-buffered MODE 5 RAM addresses (not using SHADOW) then the final lower portion with the engine is also at a fixed address. If the IRQ timing is sufficiently out such that the CRTC registers are not updated in time, then the CRTC will not produce a valid PAL signal and the display will be unstable.

For these timing sensitive games I recommend using a more accurate emulator such as beebjit, b2, jsbeeb or b-em. YMMV with BeebEm and sounds like MAME has a way to go yet in the accuracy stakes.
Bitshifters Collective | Retro Code & Demos for BBC Micro & Acorn computers | https://bitshifters.github.io/
NeoMK
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Re: Game issues on Mame 0.232

Post by NeoMK »

Thanks for the feedback. Let’s hopefully MAME emulation can be fixed to correct the timings.

Just for reference, both Uridium and White Light also exhibit similar graphic issues, though Uridium is slightly playable.

Can I ask which out of the PC emulators suggested, is the best one for running any of these timing sensitive games - executed via a dos command prompt? Thanks.
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vanekp
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Re: Game issues on Mame 0.232

Post by vanekp »

I would suggests giving beebjit a look at it runs from a dos (in windows) command prompt.
Regards Peter.
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tricky
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Re: Game issues on Mame 0.232

Post by tricky »

For the games, beebjit, b2 and b-em.
beebem works with nearly all games.
For Bitshifter demos, beebjit and with maybe an exception or two b2.
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kieranhj
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Re: Game issues on Mame 0.232

Post by kieranhj »

NeoMK wrote:
Wed Jul 21, 2021 9:54 am
Just for reference, both Uridium and White Light also exhibit similar graphic issues, though Uridium is slightly playable.
That is unsurprising as both of these games also use timing sensitive vertical rupture techniques.
Bitshifters Collective | Retro Code & Demos for BBC Micro & Acorn computers | https://bitshifters.github.io/
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