Plig faulty on BBC B

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Michael Brown
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Plig faulty on BBC B

Postby Michael Brown » Wed Jun 10, 2015 9:11 am

Hi All,

There was a game called Plig issued by the EUG back in 2002ish which says it is for the BBC B in its text.
However, it seems to want to load a database file called G.PTS at &1100 which seems to cause the error "Disk changed at line 100).
I can confirm that there is some machine code that can be changed from &11 to &13 which then loads this file in at &1300 but this means that the game screen does not appear.
I take it that I would have to find the code that looks at &1100 for the screen code and change this to &1300 and hope it works without over-writting any other code higher up in memory.

Can anyone help with this matter or do they have a fixed version they can post here.
I will take a look at this over the coming week and may resolve it myself, or in many such cases... not!.

regards,
Mick.

PS the game does work correctly in Master mode.

duikkie
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Re: Plig faulty on BBC B

Postby duikkie » Wed Jun 10, 2015 10:43 am

if you point out where the ssd can be downloaded , i can look for you at the machine code

disk changed is a DFS error , sometimes nobody knowns why that happens .
(dfs0.9 was is not, or was dfs0.9 the only one that did not have this option ?)


Michael Brown wrote:Hi All,

There was a game called Plig issued by the EUG back in 2002ish which says it is for the BBC B in its text.
However, it seems to want to load a database file called G.PTS at &1100 which seems to cause the error "Disk changed at line 100).
I can confirm that there is some machine code that can be changed from &11 to &13 which then loads this file in at &1300 but this means that the game screen does not appear.
I take it that I would have to find the code that looks at &1100 for the screen code and change this to &1300 and hope it works without over-writting any other code higher up in memory.

Can anyone help with this matter or do they have a fixed version they can post here.
I will take a look at this over the coming week and may resolve it myself, or in many such cases... not!.

regards,
Mick.

PS the game does work correctly in Master mode.

Michael Brown
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Location: Nottingham

Re: Plig faulty on BBC B

Postby Michael Brown » Wed Jun 10, 2015 2:02 pm

Hi Duikkie,

here is a copy of the disc it is featured on.

regards,
Mick.

plig.zip
(105.73 KiB) Downloaded 61 times

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jgharston
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Re: Plig faulty on BBC B

Postby jgharston » Wed Jun 10, 2015 3:39 pm

duikkie wrote:if you point out where the ssd can be downloaded , i can look for you at the machine code.
disk changed is a DFS error, sometimes nobody knowns why that happens.
It's because it's loaded right smash on top of the DFS workspace, specifically, the open files information at &1100-&11FF. So, next time DFS looks in it's open file workspace for something it thinks the disk has been changed because the disk validation bytes in the workspace no longer match the actual disk in the drive.

You don't get the error when running on the Master because the workspace is in high RAM at &C000-&DFFF so is safe from being trampled over by something loading to &1100.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Wed Jun 10, 2015 7:13 pm

thanks for the info.
Mick.

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Sun Jan 31, 2016 4:36 pm

Now managed to change all the source code by moving it all up 200 bytes so the data now loads from &1300 instead of &1100.
Also you now have to load the basic bits at &2A00 instead of &2900 to avoid bad program.
The data that stored the "PLIG" title is now stored at &700 instead of &27B3 to avoid corruption.

Just tarting up some other problems. Making it revert back to level 1 after level 25 instead of looking for level 26 which doesn't exist.

Just testing the levels, making sure that a "no room at line" message doesn't occur and adding the instructions so should have it ready and working properly for next weekend.
I will post the finished game then.

Mick.

PS Looks like we have another lost little gem!

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Sun Jan 31, 2016 9:49 pm

Here is what I have done so far.

Just needs play testing for any faults.

PligBBC.zip
(8.27 KiB) Downloaded 56 times

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lurkio
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Re: Plig faulty on BBC B

Postby lurkio » Mon Feb 01, 2016 7:21 pm

Michael Brown wrote:Here is what I have done so far. Just needs play testing for any faults.
PligBBC.zip

The ACORNS level is a bit screwy. Doesn't register when you're on top of an apple.

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leenew
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Re: Plig faulty on BBC B

Postby leenew » Mon Feb 01, 2016 10:18 pm

lurkio wrote:The ACORNS level is a bit screwy. Doesn't register when you're on top of an apple.

Been on the LSD again Chet? :shock:

Lee

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lurkio
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Re: Plig faulty on BBC B

Postby lurkio » Mon Feb 01, 2016 11:01 pm

leenew wrote:
lurkio wrote:The ACORNS level is a bit screwy. Doesn't register when you're on top of an apple.

Been on the LSD again Chet? :shock:

Why break the habit of a lifetime? 8) :lol: :-x :-P :oops: :cry: 8-[ ](*,) :-#

Seriously, though, here are some screenshots of what I believe are bugs in Plig:
1.png
2.png
3.png

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Tue Feb 02, 2016 1:00 pm

Yes I noticed the Acorns Level too.
At first I thought it was a fault with my newly amended DFS version, so I tested the original disc in master mode on both BeebEm and b-em and found the same thing happening - So wasn't anything I had done.
Then when reading through Chris Dewhurst's notes on the EUG 63 disc, I found that he mentioned using 1's in his code to make things transparent. Also in the Acorns level you only get 3 seconds. I did change this to 30 in the source code but found that only the Acorn to your right is the right one as not only are the other 3 transparent, but also you get stuck in a endless loop if you go for them.
So it looks like the author intended you to have to try this level up to 4 times to get it right. Could this be correct? Is this level how the author intended it or is the code corrupt. I did re-transfer the whole game from the basic source code files, so if the game is wrong then the source code is wrong. I therefore assume this level to be correct - so you get 3 seconds to simply move to the Acorn over on the right of the screen to complete the level.

If anyone knows different, please let me know.
The source code is fairly simple to follow, so making any amendments shouldn't be too big an issue.

regards,
Mick.

PS Has anyone found any other errors yet?
I have had several goes myself and there is an error cause by me. If you enter an incorrect password, then it says "out of data". This was caused by compacting the basic code to avoid a "no room at line..." error. Adding back the ",-" to the end of the line with the Password names corrects this error.
I will re-post the corrected version at the weekend after I have added the Passwords to the instructions file.

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lurkio
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Re: Plig faulty on BBC B

Postby lurkio » Tue Feb 02, 2016 5:24 pm

Michael Brown wrote:...only the Acorn to your right is the right one as not only are the other 3 transparent, but also you get stuck in a endless loop if you go for them. So it looks like the author intended you to have to try this level up to 4 times to get it right ... I therefore assume this level to be correct - so you get 3 seconds to simply move to the Acorn over on the right of the screen to complete the level.

Perfectly good assumption (about a completely wacky level design!).

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CMcDougall
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Re: Plig faulty on BBC B

Postby CMcDougall » Wed Feb 03, 2016 9:44 pm

Michael Brown wrote:......after I have added the Passwords to the instructions

found them :
PWsCUT.png

had a quick play, it's ok, but could do with some music while playing.
not bad for 2002 re-make of a Arc game on ElectonUserGroup#63 disc, did the original Arc version have music :?
goes to check, and play more......

EDIT: just played more, and last level had a bug, need to collect bottom can on left first, if collect the bottom right it goes 'Game Over'
correct way & it's then back to level1!
Attachments
end.png
ImageImageImage

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Thu Feb 04, 2016 8:40 am

A very strange game with some very strange gameplay (unless it is bugged!).

Here is my final copy of Plig.
I have added the Passwords to the instructions. As usual with my loaders - you need to press P on the last page of the instructions to display the passwords (which can also be listed as data in the main game).

I have left all the levels as the author intended them (as long as he did intend them to be like they are).

It looks like they all load properly via DFS and I have had many a go and so far have not got a "no room at line...) error due to moving the basic part up from &2900 to &2A00 to avoid the amended M/C that now loads higher to avoid corrupting the DFS as the data loads for each screen.

Hopefully, this will be another restored gem (well... it's better than some of the games I have come across recently!).

Enjoy!
Mick.

PligBBC.zip
(8.2 KiB) Downloaded 43 times


PS Let me know if there is anything that needs sorting.

Michael Brown
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Re: Plig faulty on BBC B

Postby Michael Brown » Mon Feb 08, 2016 8:42 am

Just played all the screens (via using the passwords) and found that some require you to go through the walls in order to complete the screen.

Is this how the original Archimedes game was?
Does anyone have the original game and if so can they post a picture of each screen here so they can be compared to the BBC version - just in case there is an error.

regards,
Mick.


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