Poll: most challenging game that could be ported to msx in the'80

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By PingPong

Prophet (3449)

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05-12-2017, 22:20

What is the game of the 80 that was more challenging to port to msx (and does not exists) in terms of techhical limitations?
(For example because of the ram, psg, vdp limits? ). And for msx2?

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By wolf_

Ambassador_ (9769)

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05-12-2017, 22:25

One game I've never seen done well is Outrun. As in: decent controls, fast and smooth landscape movement, and colourful large sprites.

By PingPong

Prophet (3449)

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06-12-2017, 00:35

on msx1 is more challenging to do. on msx2 there is already a outrun that is not so good because of sloppy implementation.

By sd_snatcher

Prophet (3069)

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06-12-2017, 00:57

MSX1: Ghost and Goblins, Rygar
MSX2: Pole Position, Hard Driving, Ghost and Goblins, Rygar, R-Type, Hang-On, Space Harrier
MSX2+/TR: TMNT (the arcade game), Prehistoric isle in 1930, Double Dragon

By PingPong

Prophet (3449)

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06-12-2017, 01:00

sd_snatcher wrote:

MSX1: Ghost and Goblins, Rygar
MSX2: Pole Position, Hard Driving, Ghost and Goblins, Rygar, R-Type, Hang-On, Space Harrier
MSX2+/TR: TMNT (the arcade game), Prehistoric isle in 1930, Double Dragon

ok can we exp!ain briefly because it is challenging? (For example: memory, speed, vdp,etc)

By sd_snatcher

Prophet (3069)

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06-12-2017, 01:15

MSX1:GnG/Rygar: Number of sprites per line, lack of smooth scroll
MSX2/Pole Position: smooth horizontal scroll, sprite size
MSX2/Rygar: smooth horizontal scroll, multiple planes, sprite size.
MSX2/Hard Driving: CPU speed, blitter speed
MSX2/R-type: Maybe something similar to the SMS could be done
MSX2/Hang-On: smooth horizontal scroll, sprite size
MSX2/Space Harrier: Maybe something similar to Feedback could be done
MSX2+,TR/TMNT (the arcade game): Sprite size and color limit, number of sprites per line, or blitter speed
MSX2+,TR/Prehistoric Isle in 1930: Sprite size and color limit, number of sprites per line
MSX2+,TR/Double Dragon: Maybe something similar to the SMS could be done

By santiontanon

Paladin (834)

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06-12-2017, 06:29

Another one that comes to mind is "Stunt Car Racer", since the VDP of the MSX 1 is really not the best when it comes to 3D rasterization algorithms I think it would be quite a challenge to port this one! there was a ZX Spectrum version that was pretty good though!

By andrea.denara

Resident (60)

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06-12-2017, 10:03

I would only add a comment on the post above:

The Msx is not the only machine that have graphics limitations, ZX spectrum has a lot of limits, C64 is the target machine of early 80's and software of that years are made main for it.
Msx1 has no hardware scroll and 4 sprite for line, but Msx2 is great, you can do horizontal scroll and vertical by hardware,
is very similar to master system (but different)
So, I think no problem to do the software listed above, the problem is lack of time.
I was a teenager when I meet msx, but today with a family it's hard to find some time to develop a game.
Probably many users have the same problem.

By TomH

Champion (327)

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06-12-2017, 16:51

santiontanon wrote:

Another one that comes to mind is "Stunt Car Racer", since the VDP of the MSX 1 is really not the best when it comes to 3D rasterization algorithms I think it would be quite a challenge to port this one! there was a ZX Spectrum version that was pretty good though!

Even the C64 version isn't that bad, and that thing doesn't even run at 1Mhz in PAL territories. Different CPUs, etc, but a sub-1Mhz 6502 is definitely slower than a 3.58Mhz Z80.

A serviceable MSX port could be achievable by a talented and dedicated programmer though, as it looks to be playable even when only somewhere in the 5–10 fps range (different times, different standards, etc), and — having just measured it — the Spectrum display window is only somewhere around 224x144 pixels, so a little less than 4kb for the animated region.

On the CPU side you'd run a pretty simple split process, whereby the main thread of processing generates the next frame, and an interrupt routine shovels the most recently completed frame to VRAM for as long as fast access is available, then returns and lets frame calculation continue until the next interrupt. Theoretical maximum on an NTSC device: 12fps, with a bit less than 30% of CPU time lost to VRAM pushing. Of course, the interrupt routine would return immediately if a next frame weren't available yet and 12fps is very optimistic so you'd end up with a number somewhere less than 30% in real life.

The main problem would be squeezing two video buffers into VRAM. You might need to be smart enough to generate a tiled display directly for screen 1, otherwise I guess it's one of the undocumented half-bitmap arrangements of screen 2 that breaks you on an MSX 2. So, ummm, implement a separate MSX 2 version that's graphically better all around?

The actual 3d plotting is relatively simple on that title, at least. On the 8-bit versions there's an assumption that you're generally upright or close enough, so for each floor section it just fills from the top of the polygon down to the bottom of the screen and then draws the vectors on top. Only the top sections of the track get the real 3d maths applied, the sides and bottom are just sort of implied by the fill-to-the-bottom trick. So most views are maybe a dozen vertices at most. Which would help a lot with a hypothetical screen 1 adaptation since tiles make for fast area fills.

Am I dedicated enough to test this assertion? Almost certainly not. It's armchair work at best.

By santiontanon

Paladin (834)

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06-12-2017, 19:11

Hmmm, interesting! 10 fps would be already amazing I think! Definitively a project I'd follow if you decide to give it a try! Big smile (MSXDev'18? Wink )

By PingPong

Prophet (3449)

PingPong's picture

06-12-2017, 19:47

The vdp hybrid screen 2 mode works on msx2 too. It does not work on some vdp clones

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