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AKA :
Count Duckula +5D 102%
Credits :
Intro used in this crack:
Scrolltext and other text in this release : ()
Download :
Look for downloads on external sites:
Pokefinder.org
Production Info
Submitted by Pitcher on 12 January 2019
30 years since release, we finally manage to give you a fully working version with some rather unique trainers.
# Key bug is in the game's second door, due to a rather severe original bug in code.
This causes the Derbyshire ram, Laser and Twilight versions to totally crash. The Ikari & Talent, Dcs and Ics versions flicker like mad.
In our version, this bug has been identified and fixed.
What is the issue? A routine, that is a core part of the sprite handling, creates a table on $03 and reads from it using "lda $0003,y". But it stores using "stx $03,y". In the first instance, if Y passes the page boundary, it reads from the lower part of the stack. But the store instruction wraps and starts writing to $00 and $01, which alter the memory configuration after poking in $01. The general effect is that the Kernal ROM is flipped in, which means the triggered IRQ starts using the vector at $0314/5 and not the $fffe/f one the game normally uses.
Given that an area on zero page is initiated, it's obvious that the intention is not to read or write beyond the end of that but it does, and the bug comes into play. We haven't bothered to dig to the bottom of why this happens, if the root cause it anything else than no proper stop in the loop - but we have implemented a security mechanism that prevents access beyond the intended area. And the flicker after this is gone.
To validate this, go right (follow stairs up and then down) until you hit a door. Then go back up the stairs and jump right to the higher floor. Continue right until you get the key. Now go back to the door again, pass it and go right two additional screens until you see another key. When you pick it up, bad things happen in other versions.
# The second bug is the end sequence
Laser's version also points out that the end sequence is broken and that they've fixed it. We agree - it's broken and it's fixed in Lasers version. Well done, Rough!
So, what's the problem? One of the strings wrap around so that the ends starts to print on the beginning on the line. How? The game tries to print a $22 bytes long string. As this is plotting to the bitmap, every char is eight bytes. This means that they want to plot 8 times $22 bytes, i.e. $120 bytes which you of course cannot store in the x register. The check is fixed and the text moved around so that no line is more than $20 chars long.
Testing wise, this game has been a nightmare, not helped by the 30 second long tune, that after a few weeks it starts to send you slightly mad. Hence we gave it the nickname of Cunt Drakula.
So Enjoy, Bacchus & Pitcher 2019. |
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