Konami scroll patches and the AX370

By h0ffman

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27-08-2021, 01:16

I'm preparing some games for a future Twitch stream using my AX370 MSX2. Most notably I'm trying to get the patched version of Nemesis 2 working so I can have the smooth scrolling. Running the patched rom via Sofarun works, but the scroll patch isn't working.

I know this is an MSX2 but the system has the MSX2+ VDP (tested this by running Space Mambow and get the clean edges) but I did hear that these particular models, while having the VDP, are running an MSX2 bios which means checking there will not recognise the VDP chip.

My guess is there are two options

1. Without modifying the MSX in question, does anyone know if there is an updated patch which correctly detects the VDP on this machine? If not, anyone know what the code looks like for detection?

2. Is it possible to replace the bios with an MSX2+ ROM instead?

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By ren

Paragon (1868)

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27-08-2021, 14:23

According to FRS (sd_snatcher) you need a real MSX2+ machine: /forum/msx-talk/openmsx/best-machines?page=2#comment-408287 (some related discussion earlier in that thread).

If you want to get in touch with him, best bet seems Twitter, he doesn't seem that active here lately.

By h0ffman

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27-08-2021, 14:24

To be fair, he's probably not that interested in reworking his patch from 2009.

The good news is I just patched it to force it into thinking it's an MSX2+ and now I have smooth scrolling on real hardware Big smile so I have a working version for my stream when it happens.

Still interested in switching out the BIOS on this thing though, but I guess I'll ask the question in Hardware instead.

By ren

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27-08-2021, 14:51

You hacker you, would it be something to release to / share with the public?

Do you have a date planned for the stream?

By h0ffman

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27-08-2021, 14:59

Could do yes. I'll compile all the patches once I've done all of them.

Stream date is not set yet, just waiting for the scart cable to arrive.

By ren

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27-08-2021, 18:52

Since you apparently got it working via a simple hack (right?), I do wonder what this means/says in relation to FRS's statement? Perhaps results may differ on other machines / MSX2 + V9958 mod systems?

By h0ffman

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27-08-2021, 22:30

It's because the msx check is done from a byte in the bios at location #2d. My msx has the msx2+ vdp but an msx2 bios so the patch doesn't recognise it. If you upgrade you msx2 to a plus but don't switch the bios you get the same result.

There's better methods for checking the vdp without the bios now so coould be improved. My dirty hack was to just fool it into thinking its an msx2+

By ren

Paragon (1868)

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27-08-2021, 23:19

https://twitter.com/djh0ffman/status/1431327401112395781

Hmm... I'm under the impression it's running slower than I've seen / remember it. It does look like the speed is on par with the PSP version, which is actually a good thing IMO :) I've always felt that the scrolling with the patch is too fast; feels like racing, and it seems there isn't proper time to deal with the enemies, getting your power-ups etc.

Some vids for comparison: emulated turboR, MiSTer