Detecting BeebEm

discuss bbc micro and electron emulators (including mame) here!
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chrisn
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Detecting BeebEm

Post by chrisn » Sat Jul 20, 2019 1:39 pm

I notice some of the games being distributed have been patched to detect BeebEm:
Michael Brown wrote:
Sun Oct 01, 2017 9:05 am
NOTE: Due to a minor graphics fault with BeebEm 4.14, Devils Island does not work properly. However, it has been modified to detect BeebEm 4.14 and patch the problem.
How is BeebEm being detected?

I'm not working on the graphics timing / rendering emulation at the moment, but I am making other improvements (e.g, following this thread, I have fixed the CRTC and Video ULA reads), and I'd want any patched games to continue to work until we have fixed the graphics issues.
Last edited by chrisn on Sat Jul 20, 2019 1:54 pm, edited 1 time in total.

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lurkio
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Re: Detecting BeebEm

Post by lurkio » Mon Jul 22, 2019 8:08 pm

chrisn wrote:
Sat Jul 20, 2019 1:39 pm
Michael Brown wrote:
Sun Oct 01, 2017 9:05 am
NOTE: Due to a minor graphics fault with BeebEm 4.14, Devils Island does not work properly. However, it has been modified to detect BeebEm 4.14 and patch the problem.
How is BeebEm being detected?
User Sutty is the one who has done a lot of BeebEm detection, mainly for GAC games, I think.

Looks like this might be the relevant post:
:?:

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Re: Detecting BeebEm

Post by chrisn » Mon Jul 22, 2019 10:13 pm

Many thanks! Picking another patched game at random, I found the same test used in Guardian, from here. I'll add an issue to GitHub to capture this.

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Re: Detecting BeebEm

Post by Michael Brown » Tue Jul 23, 2019 12:46 pm

Basically, BeebEm has a few faults with its emulation.
This means several games do strange things that they do not do on a real BBC or under B-em.

The current version of BeebEm 4.14 stores the variable &64 at location &FE10 where B-em returns a value of 0.
Therefore it has become possible to check location &FE10 and if it is &64 then jump to a routine that tries to correct the fault with the game the best it can whilst ignoring the patch if played on a real BBC or under B-em.

A few games to mention are...
1) The GAC graphical adventures like Alien from out of Space what has corruption with its text under BeebEm so does a patch to correct the text the best it can.
2) Firetrack that does not print the correct MODE7 widescreen loader so does a narrower version under BeebEm that prints amended text to fit the screen.
3) The Shapes Game from Beebug that uses MODE7 and suffers graphics glitches under BeebEm but works fine on a real BBC and under B-em. This game has no BeebEm fix at the moment and really require the author(s) of BeebEm to sort the problem.

Hopefully, the ?&64 at &FE10 will remain in all new versions of BeebEm until all the problems are sorted.

Other games with BeebEm specific issues include...
Atom Smasher from Romik that has graphics corruption.
Dune Rider from Micro Power that has MODE7 text issues with its loader.
Pharaoh's Curse from H.Soft where screen goes blank at start due to issues with light pen reading.
Rig Attack from Tynesoft where screen goes blank at start.

It would be great if all the above games could be made to work properly under BeebEm as they do under B-em.

Hope this helps
regards,
Mick.
Last edited by Michael Brown on Tue Jul 23, 2019 12:48 pm, edited 2 times in total.

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Pernod
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Re: Detecting BeebEm

Post by Pernod » Tue Jul 23, 2019 1:38 pm

Michael Brown wrote:
Tue Jul 23, 2019 12:46 pm
Hopefully, the ?&64 at &FE10 will remain in all new versions of BeebEm until all the problems are sorted.

It would be great if all the above games could be made to work properly under BeebEm as they do under B-em.
I really don't approve of 'fixing' games to work with specific emulators. It's the emulator that is wrong, not the game! This just creates and spreads more hacks around the internet.
Either fix the emulator, or use an emulator that works!
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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BigEd
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Re: Detecting BeebEm

Post by BigEd » Tue Jul 23, 2019 1:50 pm

But it would be great for this 'bug' in beebem to be fixed only after all known emulation issues with games are fixed.

And it would be bad for this 'bug' to be fixed first, because that just breaks games that have workarounds.

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Re: Detecting BeebEm

Post by Michael Brown » Tue Jul 23, 2019 2:15 pm

I think myself and others have posted the issues with BeebEm here for nearly 6 or 7 years and have asked for the emulator to be fixed and some of these fixes have been sorted like the keyboard issue with some games like Doctor Who The First Adventure etc,

Sadly the other fixes like with the games mentioned above have not yet.
I originally ran 2 sets of games discs with BBC Micro/B-em games on one and BeebEm patched versions on the other.
Once the ?&FE10 detection came my way I was able to create one disc that contained versions of the games that worked on both main emulators as well as a BBC Micro.

I would have hoped that until such time that the author(s) of BeebEm fixed these issues, that the workaround versions would be accepted as the best alternative.
Obviously a perfect solution would be to get BeebEm fixed and then it would be no problem for me to remove the fixes and re-post the discs with the original versions.
That would be no problem at all.

Would it help the author(s) of BeebEm if we all posted a complete list of all affected games detailing exactly what the issues under BeebEm are and then once we have all inputted our issues, then the author(s) then sorted the emulator once and for all.

I think I have mentioned all the games that I have amended.
As for Guardian, that was an Electron title that required a slow-down routine to work on a BBC. Then we found out that it worked at a different speed under BeebEm than under B-em and a BBC so the detection routine was added.

What we have done is not what we really wanted, but it was what we could do in the meantime whilst we wait for an emulator fix.

As for which emulator to use. I really like the graphics of B-em, but prefer the ease of BeebEm and would not have been able to copy over a lot of the inlay info for the games without the paste facility.

regards,
Mick.
Last edited by Michael Brown on Tue Jul 23, 2019 2:20 pm, edited 3 times in total.

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Re: Detecting BeebEm

Post by Pernod » Tue Jul 23, 2019 2:58 pm

BigEd wrote:
Tue Jul 23, 2019 1:50 pm
But it would be great for this 'bug' in beebem to be fixed only after all known emulation issues with games are fixed.

And it would be bad for this 'bug' to be fixed first, because that just breaks games that have workarounds.
Are you serious? If the BeebEm bugs are fixed then there's no need for these games with workarounds, you can go back to the original game as it's author intended.
Michael Brown wrote:
Tue Jul 23, 2019 2:15 pm
I would have hoped that until such time that the author(s) of BeebEm fixed these issues, that the workaround versions would be accepted as the best alternative.
Obviously a perfect solution would be to get BeebEm fixed and then it would be no problem for me to remove the fixes and re-post the discs with the original versions.
That would be no problem at all.
I appreciate what you're saying but I doubt BeebEm will be fixed anytime soon, someone needs to take ownership of it. There are multiple forks of BeebEm on github now, some may have fixes, but no-ones packaging and releasing them. Having such an old codebase probably requires 10+ years old development tools to build it too, it needs modernising to be maintainable and attract developers.
Personally I prefer the b-em code, it's much cleaner and easier to work with, but my hands are full with MAME.

Both BeebEm and b-em have their strengths and weaknesses, but if a game doesn't work in BeebEm then simply use b-em.

As we don't even have a public archive of clean software (like http://archive.worldofdragon.org/archive/index.php) then these 'fixed' games will be seen as original. I've seen BBC games reviewed on YouTube (posted to the Acorn FB group) where the reviewer clearly has no BBC history and was reviewing your versions with added instructions thinking this was how they were original released.

We need to be preserving history! If your versions that are becoming widely available are the only ones easily found in another 20 years then we have seriously failed.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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BigEd
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Re: Detecting BeebEm

Post by BigEd » Tue Jul 23, 2019 3:05 pm

Pernod wrote:
Tue Jul 23, 2019 2:58 pm
BigEd wrote:
Tue Jul 23, 2019 1:50 pm
But it would be great for this 'bug' in beebem to be fixed only after all known emulation issues with games are fixed.

And it would be bad for this 'bug' to be fixed first, because that just breaks games that have workarounds.
Are you serious? If the BeebEm bugs are fixed then there's no need for these games with workarounds, you can go back to the original game as it's author intended.
Hmm, did I make a mistake in what I wrote? I wrote "only after" and "first" in those sentences, intending to be clear. Yes, it's best to fix all bugs. But, while bugs remain - which is presently true - it's best to have an easy way to detect the emulator. So, fix this bug, which allows detection, last.

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Re: Detecting BeebEm

Post by lurkio » Tue Jul 23, 2019 4:11 pm

Pernod wrote:
Tue Jul 23, 2019 2:58 pm
... I doubt BeebEm will be fixed anytime soon, someone needs to take ownership of it. There are multiple forks of BeebEm on github now, some may have fixes, but no-ones packaging and releasing them.
chrisn has been fixing bugs in BeebEm for Windows, and his fork seems to be the most up-to-date version of the code. One particularly useful fix was for quite a nasty 8271 emulation bug:
And user SpaceFlightOrange has recently volunteered to try to develop BeebEm for Mac, though it's early days yet:

Pernod wrote:
Tue Jul 23, 2019 2:58 pm
As we don't even have a public archive of clean software (like http://archive.worldofdragon.org/archive/index.php) then these 'fixed' games will be seen as original. I've seen BBC games reviewed on YouTube (posted to the Acorn FB group) where the reviewer clearly has no BBC history and was reviewing your versions with added instructions thinking this was how they were original released.
The "About" page on bbcmicro.co.uk explains the ethos of the site, which is to provide versions of the games that have been made as easy to play (hence the added instructions) and as compatible with a variety of storage solutions and emulators as possible.

Ideally, we'd also have people working on preserving a second, separate archive of games where the priority was authenticity -- to try to create an archive of games that are identical to the original releases, for the sake of posterity -- but that would take quite a bit of volunteer effort and time. (Anyone remember GUAPP?!)
Pernod wrote:
Tue Jul 23, 2019 2:58 pm
We need to be preserving history! If your versions that are becoming widely available are the only ones easily found in another 20 years then we have seriously failed.
I guess people have just been trying to do the best they can with the human and technical resources that are available.

:idea:
Last edited by lurkio on Tue Jul 23, 2019 4:19 pm, edited 2 times in total.

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Re: Detecting BeebEm

Post by Michael Brown » Tue Jul 23, 2019 5:15 pm

Yes myself and many others on this forum have spent a lot of time trying to make the games work the best they can using the resources at hand.

As for the added instructions, These are part of the package you buy, but not always written into the game.
I am still adding missing inlay instructions as they are found.
I hope that these provide future players of the games with the instructions needed to play the game as intended.

Even BITD I added some instructions to my games even on the 40 track versions where space provided and those discs are as old as the games themselves.
Also, don't forget we also amended some grammar and bad spelling in some of the games. This is probably something that others would have done to their collections anyway.

The idea here is to preserve the games in the best possible way we can, which may mean slightly editing them.
Also we changed some of the keys in games where keys like shift lock were used which won't work on a QWERTY keyboard.

A lot of people have helped over the past 5 years with getting these games to work for future generations.
If anyone wants to play the originals, surely they can go to STH and download the uef tapes and play those.

I would like to thank everyone who has helped me over the years to create the collection we now have today.
I will from time to time make some amendments as things get found, as long as people want me to.

regards,
Mick.

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Re: Detecting BeebEm

Post by Pernod » Tue Jul 23, 2019 5:24 pm

Michael Brown wrote:
Tue Jul 23, 2019 5:15 pm
Yes myself and many others on this forum have spent a lot of time trying to make the games work the best they can using the resources at hand.
Just to clarify, I am not criticising what you have achieved over the years, especially when it's all available at bbcmicro.co.uk with the aim of playing the games. I just don't see the need to 'fix' for BeebEm when the main use case is jsbeeb, which is clearly the most accurate emulator we currently have.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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tricky
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Re: Detecting BeebEm

Post by tricky » Tue Jul 23, 2019 6:15 pm

I think one of the main aims of bbcmicro.co.uk is to bring as many people to acorn as possible and Mike's versions certainly support that.
YouTube is another way to bring people in and most of the videos that I have seen have used beebem, probably because it produces videos.
I have a number of fixes in my beebem, but it is based on an older version that had speech support and now has quite a bit of extra debugging code.
I would imagine that MAME would also be popular, but it is still a little tricky to use (fullscreen) and I'm not sure where compatibility is, but I know it has come a long way with Pernod's help.

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Re: Detecting BeebEm

Post by lurkio » Tue Jul 23, 2019 6:16 pm

Pernod wrote:
Tue Jul 23, 2019 5:24 pm
I just don't see the need to 'fix' for BeebEm when the main use case is jsbeeb, which is clearly the most accurate emulator we currently have.
What if people want to play the games offline? BeebEm is still the first desktop emulator to appear in the results of a Google search for bbc micro emulator.

Also, the work to fix the games for BeebEm was started long before JSBeeb was even a twinkle in Godbolt's eye...

Btw, JSBeeb does also have issues running certain games, and dev work on it seems to have stalled, sadly:
:idea:

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leenew
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Re: Detecting BeebEm

Post by leenew » Tue Jul 23, 2019 6:55 pm

Do you think Matt would hand over development work to anyone else who has a little more time?

Lee

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Re: Detecting BeebEm

Post by danielj » Tue Jul 23, 2019 7:00 pm

It's on github, anyone can write a fix and issue a pull request.

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Re: Detecting BeebEm

Post by chrisn » Tue Jul 23, 2019 7:06 pm

Michael Brown wrote:
Tue Jul 23, 2019 12:46 pm
Hopefully, the ?&64 at &FE10 will remain in all new versions of BeebEm until all the problems are sorted.
Yes, that's the plan, and is the reason I started this thread:
chrisn wrote:
Sat Jul 20, 2019 1:39 pm
... I'd want any patched games to continue to work until we have fixed the graphics issues.
Michael Brown wrote:
Tue Jul 23, 2019 2:15 pm
Would it help the author(s) of BeebEm if we all posted a complete list of all affected games detailing exactly what the issues under BeebEm are and then once we have all inputted our issues, then the author(s) then sorted the emulator once and for all.
This would be helpful, to me at least, as there may be specific issues I'm not aware of (e.g, the GAC adventures, Atom Smasher, Dune Rider, Pharaoh's Curse, Rig Attack that you mentioned). I know that lurkio posted the issue with The Shapes Game to GitHub. But if, as you say, the issues have been posted here, then I can search the forum.
Michael Brown wrote:
Tue Jul 23, 2019 2:15 pm
What we have done is not what we really wanted, but it was what we could do in the meantime whilst we wait for an emulator fix.
I have to say that bbcmicro.co.uk is a fantastic collection =D> and I am hugely appreciative of the extra effort that's been put in to make the games work with an imperfect emulator [-o<

The other thing to remember is that we each contribute to the projects we find interesting, in our own spare time. Nothing happens without contributors. I like working on BeebEm for Windows. Whether I'm able to fix all the issues with it, who knows? But my goal is to make it a more accurate emulator, improve its user interface, modernise the codebase a little, and integrate feature improvements from others in the community.

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Re: Detecting BeebEm

Post by Michael Brown » Wed Jul 24, 2019 8:56 am

Yes, when I started amending the games for BeebEm, only BeebEm and B-em were around.

Now onto more issues...

Twin Kingdom Valley by Bug Byte. There is some Mode7 problem under BeebEm with the instructions in the main game. The top line of text on the last two pages disappears. Not sure if this is caused by the double height text at the bottom of the page pushing it up, but the cursor is in a different place during these pages than the previous ones which seem OK.
No problem under B-em.

The other GAC type games affected are Winter Wonderland, Ransom, Gotta Go Home and Operation Safras.

As for Atom Smasher... The Graphics error is in main game when hit by blue neutron in BeebEm. The screen should shake from side to side. A patch was added which does a sort of fix. The game works correctly in B-em which should show you the difference/issue.

hope this helps.

regards,
Mick.
Last edited by Michael Brown on Wed Jul 24, 2019 8:57 am, edited 1 time in total.

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Re: Detecting BeebEm

Post by jgharston » Wed Jul 24, 2019 8:24 pm

Michael Brown wrote:
Tue Jul 23, 2019 12:46 pm
Hopefully, the ?&64 at &FE10 will remain in all new versions of BeebEm until all the problems are sorted.
Reading &FE10 does not return ?&64, it returns ?&FE10. In BeebEm the SERULA is a read/write device, and reading from it returns whatever was previously written to it. When not reading or writing bytes to/from tape, with the tape motor off, and with RxBaud=TxBaud=9600 that wlll be &64 (note, *not* ?&64).

Code: Select all

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

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Re: Detecting BeebEm

Post by Michael Brown » Thu Jul 25, 2019 8:31 am

Yep, sorry about the ? error.

A simple test is...

10 IF ?&FE10=&64 THEN PRINT "BeebEm".

You could also change the &64 to simply 100.

This routine is how BeebEm4.14 gets detected.

regards,
Mick.

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Re: Detecting BeebEm

Post by Rich Talbot-Watkins » Thu Jul 25, 2019 9:22 am

I don't particularly agree with the principle of fixing up legacy code which worked properly on real hardware so that it runs as expected on an inaccurate emulator. We should of course be attempting to improve emulator accuracy, using issues with emulated software as our testing ground.

That said, I think if we do want to be able to detect whether code is running on an emulator or not, it wouldn't be a bad thing to introduce a deliberate 'glitch in the matrix' in the emulated environment that can be explicitly tested, rather than having to rely on emulation inaccuracies/shortcomings which (hopefully) will get fixed in the future. An example of this might be (for example), to respond to a read from CRTC register 255 (which doesn't exist on real hardware, as only registers 0-31 are valid, and only 0-17 are defined) with a known non-zero value, something which the hardware will never do.

Regarding this:
Pernod wrote:
Tue Jul 23, 2019 2:58 pm
As we don't even have a public archive of clean software (like http://archive.worldofdragon.org/archive/index.php) then these 'fixed' games will be seen as original. I've seen BBC games reviewed on YouTube (posted to the Acorn FB group) where the reviewer clearly has no BBC history and was reviewing your versions with added instructions thinking this was how they were original released.

We need to be preserving history! If your versions that are becoming widely available are the only ones easily found in another 20 years then we have seriously failed.
Agree with this, but I think the problem is that we still don't really have a standard file format for BBC disk images which can be used to preserve all aspects of them, protection and all. We've been down this rabbit hole a few times without clear conclusions. I and some others are reluctant to introduce yet another bespoke format as the 'standard', but meanwhile there don't seem to be many options out there. One possibility is a raw dump of clock and data bits on the disk surface (zipped), but this can't represent fuzzy bits (as used by some protection systems), and also lacks the flexibility of a chunked file format.

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Re: Detecting BeebEm

Post by Rich Talbot-Watkins » Thu Jul 25, 2019 9:33 am

Just wanted to add that, while BeebEm for a long time was the best we had, and a lot of fantastic work went into it over the years (for which we are all immensely grateful), it's slipped behind others in terms of accuracy and performance. There are now far more accurate emulators: Sarah's B-Em, Tom Seddon's b2, Pernod's great work on MAME, and of course jsbeeb. I agree pretty much with Pernod's statement that if a game doesn't work properly with BeebEm, the best thing to do is just to turn to another emulator in which it does!
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Re: Detecting BeebEm

Post by lurkio » Thu Jul 25, 2019 11:25 am

Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:22 am
I don't particularly agree with the principle of fixing up legacy code which worked properly on real hardware so that it runs as expected on an inaccurate emulator.
Unless that emulator has been the most popular Beeb emulator for many years; the work to fix games for it began long before more recent emulators were created; it's still the top desktop Beeb-emulator Google-search hit; it's more user-friendly in several ways than the other ems -- easier to get started with -- particularly for casual users; and it can actually emulate some games better than at least one of the more recent emulators.
Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:22 am
We should of course be attempting to improve emulator accuracy, using issues with emulated software as our testing ground.
I don't think anyone would disagree with that.

chrisn has been fixing bugs in BeebEm for Windows, and his fork seems to be the most up-to-date version of the code. One particularly useful fix was for quite a nasty 8271 emulation bug:
And user SpaceFlightOrange has recently volunteered to try to develop BeebEm for Mac, though it's early days yet:

Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:33 am
Just wanted to add that, while BeebEm for a long time was the best we had, and a lot of fantastic work went into it over the years (for which we are all immensely grateful), it's slipped behind others in terms of accuracy and performance. There are now far more accurate emulators: Sarah's B-Em
I think I agree that B-em's emulation, including but not limited to its emulation of MODE 7, is better than BeebEm's, but I find B-em a bit more fiddly to use than BeebEm.

BeebEm's great strength, I think, is the layout of its menus and options, which are relatively easy to understand and use.

B-em's one big drawback, for me, is that its Teletext font isn't as smooth or as good-looking as BeebEm's, which is a shame, because the MODE 7 font is the best of all the 8-bits'.

And there isn’t a native Mac version of B-em.

Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:33 am
Tom Seddon's b2
b2 is very impressive but it runs on fewer macOS versions than BeebEm and has very non-standard menus, on macOS at least. Thus in b2 it's not immediately obvious how to load third-party ROMs, for example. And generally the complicated and numerous menus and options in b2 are much trickier to navigate and use than BeebEm's -- which might put casual users off.

Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:33 am
Pernod's great work on MAME
Again, very impressive work. But not as easy as BeebEm to install and get going with.

Rich Talbot-Watkins wrote:
Thu Jul 25, 2019 9:33 am
and of course jsbeeb
Several games that work in BeebEm simply fail in JSBeeb:

I'm glad we now have a variety of emulators and I'm awed and impressed by the people who created them and continue to work on them. But all the emulators have flaws.

:idea:

Moderators note: The discussion about Uridium and other games not working on JSBeeb has been moved to it's own thread here ;-) Mark
Last edited by 1024MAK on Sat Aug 03, 2019 11:24 pm, edited 2 times in total.

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Re: Detecting BeebEm

Post by jgharston » Thu Jul 25, 2019 4:47 pm

Michael Brown wrote:
Thu Jul 25, 2019 8:31 am
10 IF ?&FE10=&64 THEN PRINT "BeebEm".
Hmmm....
10 *FX7,4
20 IF ?&FE10=&64 THEN PRINT "BeebEm"

*Configure Baud 4
Ctrl-Break
IF ?&FE10=&64 THEN PRINT "BeebEm"

Code: Select all

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

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Re: Detecting BeebEm

Post by 1024MAK » Sun Jul 28, 2019 4:50 pm

So having read through the whole thread, some things that I think are worth saying:
  • Be very careful with “on a plain BBC B” as many machines in use are no longer “plain”. Firstly because most have either a floppy disk system, Econet or other mass storage system these days, and secondly, a fair number have sideways RAM.
  • Even if a Beeb does not have any internal or external expansions, there are various board revisions and not all Beebs have the same make of chips. So there may well be minor differences.
  • And of course, B+ and Master machines are different again.
  • It is inevitable that ‘fixed’ versions of games and other software will outnumber archives of original ‘untouched’ software. The ‘fix’ could be moving code around to allow a cassette only title to work in a system fitted with a FDD. Or it could be to disable or remove protection systems. Or it may to be fix a known bug. Or it may be to allow the software to work on a Master.
  • Really, there should be an archive that contains both copies of original untouched software, as well as the various ‘fixed’ versIons. But there also needs to be a file detailing what is known about the different versions. Copies of instructions/booklets/ cassette tape inlays/etc. should also be in the archive. As well as any other details that are thought worthwhile keeping (authors, coders, graphic artists, musicians, original software house/distributor, copyright holder, original price etc..).
  • Of course, emulators should be as accurate as possible, but we are talking emulation, not 100% cycle and hardware timing accurately here. So if the game/software has already been modified (‘fixed’), and is no longer ‘original’ then I don’t see why a minor modification can’t be applied if it means it will work on a wider range of emulators. As long as it still works on the real machine(s) it was intended for. Obviously it is helpful if the code, or the package it comes with should explain what has been done and why. As far as I am concerned, this is not much different from modifying software so that it works on a wider range of real hardware (e.g. making a BBC B software also work on a Master say).
  • If it becomes known that some software has problems running on certain hardware, or certain emulators, then there should be a file giving details included in the archive.
By the way, I fully acknowledge that carrying out all the work involved in the above list is going to take a long time and will require the community to put a lot of effort in. Hence, it is unlikely to happen anytime soon, if ever.

Mark

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