Prince of Persia

[darkatx]

I still can't believe it! It never ceases to amaze me on what the Vic-20 can do.
Well Done!

[Lechuck]

I still can't believe it! It never ceases to amaze me on what the Vic-20 can do.
Well Done!

Thanks darkatx!,

yes, it is nice to see how much our VIC-20 is capable of...

Cheers

[Ghislain]

Thanks for that. As the game is using 27 columns, I was asuming it wouldn't look OK in NTSC and was initializing it just for PAL (my bad...). Good to see it might be also 'playable' (to some extent) in NTSC.

Cheers

No problem! Based on the photo I posted of your game being played on my TV, do you foresee any significant visual elements necessary for gameplay being cut off? I can tell that one of the energy bars is missing, but the game still seems quite playable to me, regardless.

You might as well incorporate a shortcut key that lets NTSC players re-center the screen or even better, just have the game autodetect the video mode and then position the screen accordingly.

[Orangeman96]

Thanks for that. As the game is using 27 columns, I was asuming it wouldn't look OK in NTSC and was initializing it just for PAL (my bad...). Good to see it might be also 'playable' (to some extent) in NTSC.

Cheers

You're famous now: the 8-Bit Guy mentions your work in his latest! -OGM

[Lechuck]

You might as well incorporate a shortcut key that lets NTSC players re-center the screen or even better, just have the game autodetect the video mode and then position the screen accordingly.

I guess I can do both. I will initialize it with the correct values depending whether it is PAL or NTSC (for NTSC, I'll use the values you mentioned in a previous post) but can also provide the option to center the screen by using cursor keys (that is already available, but only from the presentation screem, so will enable that also during the game).

I'll upload a new version with that change next week.

Cheers

[Lechuck]

You're famous now: the 8-Bit Guy mentions your work in his latest! -OGM

Thanks!. Yes, I saw it. When he mentioned he was going to try Prince of Persia in the Atari 400 mini, I thought he might mention the VIC-20 version. And he did, and also showed a short video of it

Cheers

[Ghislain]

I guess I can do both. I will initialize it with the correct values depending whether it is PAL or NTSC (for NTSC, I'll use the values you mentioned in a previous post) but can also provide the option to center the screen by using cursor keys (that is already available, but only from the presentation screem, so will enable that also during the game).

I'll upload a new version with that change next week.

I didn't know you could adjust the screen position with the cursor keys already. You see, I found out about your game from the aforementioned 8-bit guy video and he also said that the game also only works in PAL. So, I got so excited about playing it that I downloaded it and immediately from here.
I then proceeded to make the modification to get it centered on an NTSC screen.

So if you had mentioned the cursor key thing in another post or in documentation somewhere, I didn't read it.

My bad!

[Orangeman96]

You're famous now: the 8-Bit Guy mentions your work in his latest! -OGM

Thanks!. Yes, I saw it. When he mentioned he was going to try Prince of Persia in the Atari 400 mini, I thought he might mention the VIC-20 version. And he did, and also showed a short video of it

Cheers

Once again, well done! -OGM

[Lechuck]

I didn't know you could adjust the screen position with the cursor keys already. You see, I found out about your game from the aforementioned 8-bit guy video and he also said that the game also only works in PAL. So, I got so excited about playing it that I downloaded it and immediately from here.
I then proceeded to make the modification to get it centered on an NTSC screen.

So if you had mentioned the cursor key thing in another post or in documentation somewhere, I didn't read it.

My bad!

Yes, I mentioned it in the Description, in the post where I uploaded the zip with the game

But, initializing differently for PAL/NTSC is a good practice, anyway. And centering with the cursor keys, also in the game, will be helpful too…

Thanks

[Mike]

The ROM table at $EDE4 can be used to obtain useful default values for XPOS and YPOS by applying constant offsets, regardless whether you have a PAL or NTSC VIC-20:

• $EDE4 contains 12 for PAL and 5 for NTSC, when you substract 5, you get 7 for PAL and 0 for NTSC.
• $EDE5 contains 38 for PAL and 25 for NTSC, when you subtract 10, you get 28 for PAL and 15 for NTSC, the latter which should still be in order (Ghislain empirically obtained 13 instead).

This saves you a complicated PAL/NTSC detect routine, and it is exactly the same method MINIGRAFIK uses to re-center the display window for the 160x192 pixel resolution.

[Lechuck]

The ROM table at $EDE4 can be used to obtain useful default values for XPOS and YPOS by applying constant offsets, regardless whether you have a PAL or NTSC VIC-20:

• $EDE4 contains 12 for PAL and 5 for NTSC, when you substract 5, you get 7 for PAL and 0 for NTSC.
• $EDE5 contains 38 for PAL and 25 for NTSC, when you subtract 10, you get 28 for PAL and 15 for NTSC, the latter which should still be in order (Ghislain empirically obtained 13 instead).

This saves you a complicated PAL/NTSC detect routine, and it is exactly the same method MINIGRAFIK uses to re-center the display window for the 160x192 pixel resolution.

Thanks, Mike,

OK, perfect. Haven’t done it yet, so will use that method to initialize it.

Cheers

[Jeff-20]

2024 game releases have been mindblowing.

[Lechuck]

2024 game releases have been mindblowing.

Thanks, Jeff,

just uploaded a new version. It now initializes $9000 and $9001 diferently for PAL/NTSC.

Screen can be centered, now, also during the game, using the cursor keys.

Cheers

[Barney]

No matter what I try, I can't get Prince if Persia to worrk on my Vic-20. Does anybody have any suggestions?

(mod: Please check the Rules for Announcement posts, especially the section about non-announcing/discussion posts. Thanks.)

[Mike]

No matter what I try, [...]

You should be more specific in that, and give at least some information about your setup (real h/w vs. emulation, RAM size; on real h/w: brand of RAM expansion), at what point PoP diverts from the expected behaviour, and what is shown on screen instead.

In any case, PoP needs +35K RAM to run - merely +32K is not sufficient!