Upgrade Time: Encounter

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Dbug
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Upgrade Time: Encounter

Post by Dbug » Sat Mar 10, 2018 10:51 am

Hi, I wanted to look at the listing of the game Encounter (https://www.oric.org/software/encounter-1165.html) from Severn Software, and found out that both Oricutron and Tap2Bas were failing on the same place in the code:

Code: Select all

 11148 IF(B$="TIS")AND(TT=0)THENTT=A:GOTO15000
 11150 IF(B$="PET")AND(PT=0)THENPRINT:PRINT"The petrol evaporates":
So I looked directly in Oricutron and noticed that this particular line, instead of finishing by a "GOTO15000" like all the ones above instead had a "NEXT WITHOUT FORT13550"!
ErrorInLine11150.png
Looking with an hex editor we can see that instead of a code 97 (GOTO) it has F7 54
HexView.png
So basically what I'm wondering is if it's some sort of anti-printing out protection, or if it's just the result of a bad dumping of the game.
I looked at 5 different versions (OricBase, one I had laying around, plus two others downloaded from random sites) and they all seem to be the exact same version.

If any of you has the game on tape, could you take a look at this line?

Thanks :)

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Re: Encounter - Corruption, or protection?

Post by Symoon » Sat Mar 10, 2018 1:18 pm

My transfer (2007), from an original tape and without errors reported, is similar too!
Jean also did a transfer from another tape, in 2004, and is byte-for-byte similar.

So I'd rather say all tapes were like this... Protection or bad master - I've seen several bugged tapes!

(message editied after I re-discovered Jean's version)
Last edited by Symoon on Sat Mar 10, 2018 2:40 pm, edited 1 time in total.

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Re: Encounter - Corruption, or protection?

Post by Dbug » Sat Mar 10, 2018 1:59 pm

So basically the question become, what happens in the game if you try to use the petrol :)

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Re: Encounter - Corruption, or protection?

Post by Symoon » Sat Mar 10, 2018 2:41 pm

Exactly ;)

It is also possible that earlier or later versions didn't have this bug. For example, if I recall correctly, "simulateur de vol" from ASN (French version of Tansoft's Flight Simulator) had tapes with a bug, and others without.
Loriciels also corrected spelling mistakes in Kikekankoi, and so on (Tyrann authors warned of a bug in the early tapes).

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Re: Encounter - Corruption, or protection?

Post by dave3622 » Sun Mar 11, 2018 2:16 pm

The version I had ended with GOT13550. I've checked line 13550 and it seems to be the correct GOTO line so I simply corrected the spelling mistake which doesn't appear to have caused any kind of corruption in the code.
Attachments
ENCOUNTER.tap
(30.24 KiB) Downloaded 41 times

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Re: Encounter - Corruption, or protection?

Post by Symoon » Sun Mar 11, 2018 3:21 pm

Hi David!
That's interesting, do you know if it was a direct original tape dump?

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Re: Encounter - Corruption, or protection?

Post by Dbug » Sun Mar 11, 2018 4:11 pm

Interesting, this version seems to be almost identical up to half way in the program, and then there are minor changes pretty much everywhere!
DaveVersionComparison.png

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Re: Encounter - Corruption, or protection?

Post by Symoon » Sun Mar 11, 2018 4:17 pm

Dbug: it's the Basic lines addresses that change, since I think two (faulty) bytes were replaced by a single one. You can see the values differ only by 1, which is the shifting due to the removed byte.
I suspect it just changes from the faulty bytes?

From 20 years of Oric tapes transfers, I came to the conslusion that the best way to compare two Basic programs is to LLIST them, then use any Windows (or Linux or Mac or whatever) text comparison tool ;)

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Re: Encounter - Corruption, or protection?

Post by Symoon » Tue Mar 13, 2018 11:22 pm

Dbug wrote:
Sat Mar 10, 2018 1:59 pm
So basically the question become, what happens in the game if you try to use the petrol :)
bug_Encounter.png
bug_Encounter.png (2.43 KiB) Viewed 2331 times
Dom made the test today ;)
He gave a solution in the CEO-Mag in 2004, which didn't involve using the order DROP PETROL. So the game could be finished without the bug being triggered!

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Re: Encounter - Corruption, or protection?

Post by Dbug » Wed Mar 14, 2018 5:48 pm

Cool, so the version is indeed buggy :)

Can you tell me in which issue the solution is?

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Re: Encounter - Corruption, or protection?

Post by Symoon » Wed Mar 14, 2018 8:50 pm

Ceo-Mag #173, September 2004 (preceeded by several articles about the internals of the game in the 4 previous issues)

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Re: Encounter - Corruption, or protection?

Post by Dbug » Sun Mar 18, 2018 2:13 pm

Sorry for the crappy sound quality (and deafening PINGs), but here is the first part of a series of videos on how to improve old games.


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Re: Encounter - Corruption, or protection?

Post by Symoon » Sun Mar 18, 2018 3:03 pm

BTW, just uploaded Encounter on Oric.org, along with inlay, tape scans, as usual ;)

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Re: Encounter - Corruption, or protection?

Post by Dbug » Sun Mar 25, 2018 11:18 am

and here is the second part of the "upgrade encounter" videos:


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Re: Upgrade Time: Encounter

Post by Dbug » Sat Mar 31, 2018 1:39 pm

Tomorrow I'm supposed to have the third part of the video series on "upgrading" Encounter, but I was told it would be nice to see how I'm actually doing the graphics.

Since it would be too long to do that as a normal video, I did instead a tile lapse at 15 times the normal speed to give you a rough idea of what it looks like.

Hope you like it :)

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