Acornsoft Labyrinth

reminisce about bbc micro & electron games like chuckie egg, repton, elite & exileRelated forum: adventures


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kppot
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Acornsoft Labyrinth

Post by kppot » Tue Jun 12, 2018 1:32 pm

HALP!
Hello everyone. Recently I god sd-card for my Model B, and mostly all games work fine, but 747 (it stops at line 242 saying it has a syntax error, bet nevermind that) and Acornsoft Labyrinth.
The late one is actually what is all about, I am totally crazy about this game. But I cant play it. It has some sync (?) error, or I do not what. Occasionally the screen goes out of sync (??). I do not how to describe it since I never seen anything like that. TV blinks and goes black for a fraction of second. I am pretty sure it has nothing software-wise (since it uses same graphics mode as the rest of games). I played 2-3 hours for Galaforce and Gauntlet, everything is fine. But I do need help with Labyrinth. I made a short video of that problem, please find it below

https://www.youtube.com/watch?v=D_ERkhGg9UU

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Rich Talbot-Watkins
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Re: Acornsoft Labyrinth

Post by Rich Talbot-Watkins » Tue Jun 12, 2018 1:39 pm

Yeah Labyrinth programs the video controller with non-standard values, specifically the horizontal timing is too long for a PAL display. My TV even used to have some small problems with it back in the day.

It'll be easy enough to patch I suspect, but it'll need someone to find where CRTC R0 is written, and change it from 129 to 127 (and hope it doesn't break the game timing!).

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Rich Talbot-Watkins
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Re: Acornsoft Labyrinth

Post by Rich Talbot-Watkins » Tue Jun 12, 2018 1:49 pm

Found it! This works on the Acornsoft release on the STH site - haven't tested any other versions.

Code: Select all

*LOAD LABRNTH
?&18D1=127
CALL&5D00

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lurkio
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Re: Acornsoft Labyrinth

Post by lurkio » Tue Jun 12, 2018 3:10 pm

Rich Talbot-Watkins wrote:
Tue Jun 12, 2018 1:39 pm
Labyrinth programs the video controller with non-standard values, specifically the horizontal timing is too long for a PAL display.

Any idea why that was done?

:?:

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kppot
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Re: Acornsoft Labyrinth

Post by kppot » Tue Jun 12, 2018 3:35 pm

Rich Talbot-Watkins wrote:
Tue Jun 12, 2018 1:49 pm
Found it!
Cheers for the answer.
However it looks a bit complicated for me. I am using a SD collection of games so looks like I need that specific drive with the game and load it manually?
I do use special menu otherwise
http://joxi.ru/v29Xeq1i3pY95m

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Rich Talbot-Watkins
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Re: Acornsoft Labyrinth

Post by Rich Talbot-Watkins » Tue Jun 12, 2018 3:36 pm

lurkio wrote:
Tue Jun 12, 2018 3:10 pm
Any idea why that was done?

:?:
Maybe they thought it gave the graphics a strange swirly ethereal quality (which it certainly did on my TV) and thought it fitted the game. Or more likely it was just a mistake. It also has the effect of lowering the frame rate to 49.3fps but I doubt they did it to win back extra time per frame for rendering!

(The reason it does CRTC programming at all is to be able to go between its small MODE 1 and MODE 7 without the OS clearing the screen on the mode change, which would wipe out the code living between &3000 and &5800!)

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Rich Talbot-Watkins
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Re: Acornsoft Labyrinth

Post by Rich Talbot-Watkins » Tue Jun 12, 2018 3:38 pm

kppot wrote:
Tue Jun 12, 2018 3:35 pm
Cheers for the answer.
However it looks a bit complicated for me. I am using a SD collection of games so looks like I need that specific drive with the game and load it manually?
I do use special menu otherwise
http://joxi.ru/v29Xeq1i3pY95m
Yes - mount the disk image which contains Labyrinth and try entering the steps above by hand. If it works, I can walk you through permanently making the change. (Not sure how the SD card works regarding mounting disk images, or if there's some command you need to make them writable).

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lurkio
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Re: Acornsoft Labyrinth

Post by lurkio » Tue Jun 12, 2018 4:03 pm

kppot wrote:
Tue Jun 12, 2018 3:35 pm
However it looks a bit complicated for me. I am using a SD collection of games so looks like I need that specific drive with the game and load it manually?
Try this:

Code: Select all

*DIN 40
*CAT
*LOAD LABRNTH
?&18D1=127
CALL&5D00
:?:

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kppot
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Re: Acornsoft Labyrinth

Post by kppot » Tue Jun 12, 2018 5:46 pm

Rich Talbot-Watkins wrote:
Tue Jun 12, 2018 3:38 pm
I can walk you through permanently making the change. (Not sure how the SD card works regarding mounting disk images, or if there's some command
Many thanks for such excellent proposal!
I will return to this problem right after I will replace caps on my PSU
(YEP they did it!)
I was able to turn the machine off while smoke appeared )and machine naturally keep working), but there was SO MUCH smoke I decided to make a short video of such disaster
https://www.youtube.com/watch?v=DD8eAAKgnRQ

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kppot
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Re: Acornsoft Labyrinth

Post by kppot » Tue Jun 12, 2018 11:45 pm

lurkio wrote:
Tue Jun 12, 2018 4:03 pm

Try this:

Code: Select all

*DIN 40
*CAT
:?:
Cheers, this is exactly what I needed. It would takes hours navigating from DIN 0 to DIN 509 :mrgreen:

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Lardo Boffin
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Re: Acornsoft Labyrinth

Post by Lardo Boffin » Wed Jun 13, 2018 6:37 am

I think you can maybe do *DCAT? This lists the disc contents one at a time but without all the typing. Not 100% sure as I have not used one for a while.
BBC model B 32k issue 4, 16k sideways RAM, Watford 12 ROM board, Retroclinic Datacentre + HDD, Viglen twin 40/80 5.25" discs, acorn cassette, Acorn 6502 coproc
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