J. P. Winkle -- is it bugged?

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By wyrdwad

Paladin (814)

wyrdwad's picture

31-01-2019, 15:39

I am somewhat interested in finding out the cause of the problem, but I'm not sure I'd be the one to pinpoint it, considering I wasn't even smart enough to include the ,R switch on that BLOAD command. Wink My primary goal with this topic was to determine whether or not the cartridge I received from eBay was defective, and I'm quite confident now that it is not -- the problem is in the software, not the hardware (or if it is in the hardware, it's in my hardware somehow, not the cartridge I received; though since no other games in my collection exhibit this behavior, I'm inclined to say it's the software!). So rather than expend too much energy chasing demons here, I think I'll just go back to playing one of the mountain of other games in my backlog (when I'm not translating) and see if I can solve the mystery of J. P. Winkle at a later date.

So for the time being, I guess just consider this topic a general report/advisory that owners of the Panasonic FS-A1WX system may want to think twice before purchasing J. P. Winkle cartridges!

Thanks for your help, though, to everyone who replied.

-Tom

By MP83

Master (194)

MP83's picture

31-01-2019, 18:09

Just tried this game on my FS-A1WX system (with 512kb main RAM). The game is also freezing for me from time to time, forcing me to unfreeze it by pressing the hardware pause key, as if the game code somehow activates the hardware pause function by mistake. The game especially likes to freeze about 5 times in a row whenever switching rooms, when the screen is scrolling.

By NYYRIKKI

Enlighted (5423)

NYYRIKKI's picture

31-01-2019, 20:27

I had to test the game on openmsx, but as I expected, it fails to freeze there. It seems you have really found some hidden control feature from A1WX that we are not aware of yet... Exciting, I must say... This machine seems to have lot of secrets.

BTW one thing I would like to hear is, does executing: OUT 64,8:OUT 65,0 before BLOAD"WINGKLE.BIN",R make any difference?

By wyrdwad

Paladin (814)

wyrdwad's picture

31-01-2019, 21:10

To my amazement... yes! Executing that line before the BLOAD fixes the problem entirely. No more freezing whatsoever!

What in the world does that mean? And how the hell did you figure that out?! Wink

-Tom

By mars2000you

Enlighted (5525)

mars2000you's picture

31-01-2019, 22:17

This instruction activates the 5.37 MHz Mode on the Panasonic MSX2+.

See https://www.msx.org/wiki/Panasonic_FS-A1WX

By Grauw

Ascended (8612)

Grauw's picture

31-01-2019, 21:31

Just the timing may have changed, making the bug not occur?

The pause key puts the Z80 in a wait state, so this also affects the timing.

By NYYRIKKI

Enlighted (5423)

NYYRIKKI's picture

31-01-2019, 21:59

wyrdwad wrote:

And how the hell did you figure that out?! Wink

MP83's tip that screen scrolling makes the game freeze gave me an idea that this might be somehow VDP related. I remember reading from somewhere in this forum that this machine has a bit special timing when it comes to VDP. I also did take a peek inside game code and it seems to rely quite a much to CPU timing & use BIOS calls to do pretty much everything, so I thought the problem is unlikely in some "wrong values sent to I/O ports" type of problem... So... I did not really "figure it out" but the idea was simply "Hmm... what happens if we mess up with the timing a bit more?"

By gdx

Prophet (3156)

gdx's picture

01-02-2019, 08:20

It looks like an interruption problem.
Try these versions and tell me if one works please.
https://mon-partage.fr/f/DgIN42eO/

By wyrdwad

Paladin (814)

wyrdwad's picture

01-02-2019, 16:46

I assume you wanted me to test each of them without using the OUT 64,8:OUT 65,0 commands, correct? If so, then I'm sorry to say none of them fixed the problem -- and in fact, JPWINKLA.BIN actually had it even worse than before, freezing every 5 seconds or less.

JPWINKLE.BIN may have been a tiny improvement over the base rom, though it's hard to say. It didn't seem to freeze AS often, but that could've just been luck of the draw.

And JPWINKA2.BIN seemed roughly the same as the base rom.

-Tom

By gdx

Prophet (3156)

gdx's picture

02-02-2019, 00:40

  • JPWINKLE.BIN is an unmodified version.
  • JPWINKLA.BIN is an version that use interruptions of system.
  • JPWINKA2.BIN is an version with the scrolling buffer moved to unused area in RAM because it overwrite the variables of the system.
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