Problematic Holiday Lemmings 94 demo disk

MethodGit · 31 October 2010, 06:22

I recently discovered one of the Holiday Lemmings 94 disks in TOSEC to be a demo disk rather than the full version. Interested, I wanted to play through it for fun, but it seems no matter what quickstart config I use, the game will freeze on a black screen (with the lemming hand cursor still interactive) after you click the mouse button on the level info so you can start the level.

I know for a fact that the demo available on one of The One's coverdisks from January 1995 works brilliantly, so I attempted to do file comparisons. Only the executable differed from the two versions, and the TO version was crunched, so I had to unpack it first.

Upon unpacking, TO's demo exe weighed in at 142948 bytes, compared to the TOSEC exe's 142944 bytes. Hex-wise, the files aren't dramatically different, with only the sporadic byte changes incurred no doubt as a result of the packing process the TO exe originally went through, though at some point (mainly at the start of the "end of demo" text) the files will veer off one another by just one character, and it stops becoming easy to find major hex changes. I attempted to get around this by editing the TO exe bit-by-bit until the files were more aligned with one another, but despite all this I can't find any significant changes aside from the aforementioned sporadic byte modifications, and I still can't work out why one exe fails and the other performs marvellously.

So, if anyone wants to look into it further - by whatever means necessary - then find "Lemmings - Holiday Lemmings 1994 (1994)(Psygnosis)[a].7z" on the EAB file server, and grab the TO version from the above link, and frolic away!

(Of course, if navigating the server is too much bother, I *could* zone up the two versions if there are enough requests.

)

mai · 31 October 2010, 09:40

...at least A1200 works fine here.

TCD · 31 October 2010, 09:47

Quote:

Originally Posted by mai

...at least A1200 works fine here.

Here as well. A500 & A600 doesn't though.

MethodGit · 31 October 2010, 15:46

Strange. An AGA-only demo? That doesn't sound right somehow. Lemme check anyway.

MethodGit · 31 October 2010, 17:06

Okay, what it seems to boil down to is processor. The demo will not work correctly on anything below a 68020.

On a 68000 the "freeze on black screen" bug occurs. On a 68010 it won't even get past the initial opening text in the CLI window. On all other processors - including a 68060 - it'll work as intended. Even with JIT and CPU speed cranked all the way up!

This surely makes for one fudged up executable if it's been compiled to fail on the earliest Amiga models. Maybe someone with more technical wizardy could explain what went wrong somewhere in the code?

Since the 68020 is faster than the 68000, maybe it's a display speed issue.

TCD · 31 October 2010, 17:12

Quote:

Originally Posted by MethodGit

Maybe someone with more technical wizardy could explain what went wrong somewhere in the code?

Who really cares (except you of course

) about it anyway? A working non-demo version exists, so I wonder what the actual use of such an investigation would be.

MethodGit · 31 October 2010, 18:24

Because something obviously had to go wrong in order for a program to lose all 68000/010 compatibility when a similar demo works on all Amigas? People need to know these things in case you get more threads of this calibre again in future.

mai · 31 October 2010, 18:33

...thanks for info, [68020] added.

TCD · 31 October 2010, 18:54

Quote:

Originally Posted by MethodGit

People need to know these things in case you get more threads of this calibre again in future.

Fingers crossed that it doesn't happen...

MethodGit · 01 November 2010, 13:06

I should probably have asked that if anyone happens to own a real 68000 Amiga, then could they test the disk on one to confirm that the problem occurs under real hardware also? Thanks.

fitzsteve · 01 November 2010, 14:04

Quote:

Originally Posted by MethodGit

I should probably have asked that if anyone happens to own a real 68000 Amiga, then could they test the disk on one to confirm that the problem occurs under real hardware also? Thanks.

I can do that later, can you zone the ADF so I'm using the same one?

Give me somthing to do instead of boring housework

My A600 has 68k / 020 and 1.3 / 3.1 roms so it should be good platform to test all configurations for you on real hardware

MethodGit · 01 November 2010, 16:04

Just zoned it for you, buddy.

Even put it in a zip for you in case Amigas still have trouble with the 7z format.

Mad-Matt · 01 November 2010, 16:26

This seems to work ok in uae 68000 with ce and mc dissabled.

Toni Wilen · 01 November 2010, 16:29

I can't see any loading problems. Works until level is supposed to start and then it crashes because it writes longs to odd address (need 68020+)

MethodGit · 01 November 2010, 18:01

Quote:

Originally Posted by Mad-Matt

This seems to work ok in uae 68000 with ce and mc dissabled.

Oooooh so it's an issue with the More Compatible tag? I did test with CE both on and off and got the freeze issue.

MethodGit · 01 November 2010, 18:49

Okay, so here are my findings based on certain settings...

68000, Cycle Exact on (Quickstart A500 default) = freezes on black screen.
68000, Cycle Exact off, More Compatible on = freezes on black screen.
68000, Cycle Exact off, More Compatible off = works!
68010, Cycle Exact on, More Compatible on/off (doesn't really matter) = hangs on opening text CLI screen.
68010, Cycle Exact off, More Compatible on = works!
68010, Cycle Exact off, More Compatible off = works!

Say Toni, would you be able to explain why MC would be the one conflicting with the game's code and its performance on certain processors (like, how does it work and what not)?

Kinda ironic given its name and all.

Toni Wilen · 01 November 2010, 19:03

Black screen is CORRECT behavior on a 68000! It requires 68020 or "non compatible 68000".

EDIT: Compatible = includes address error exception checks (more work to do), non compatible = ignores address errors = faster.

MethodGit · 01 November 2010, 19:27

Quote:

Originally Posted by Toni Wilen

Black screen is CORRECT behavior on a 68000! It requires 68020 or "non compatible 68000".

Then I guess it's just a pretty borked executable. Like I said, the version distributed by The One has no such problems on a 68000.

Quote:

EDIT: Compatible = includes address error exception checks (more work to do), non compatible = ignores address errors = faster.

Thanks for the explanation, Mr Wilen.

fitzsteve · 01 November 2010, 19:48

Hey!

I guess you guys have it sussed, but anyway I tried on my A600 and in 68k mode it black screens at the start of the level. (Tried both 1.3 and 3.1 Rom)

In 020 mode it worked just fine

Steve.

Eclipse · 08 November 2010, 03:56

There was probably meant to be an AGA version at some point. I'm guessing things might have got mixed up between an AGA and standard demo.

31 October 2010, 06:22	#1
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Problematic Holiday Lemmings 94 demo disk I recently discovered one of the Holiday Lemmings 94 disks in TOSEC to be a demo disk rather than the full version. Interested, I wanted to play through it for fun, but it seems no matter what quickstart config I use, the game will freeze on a black screen (with the lemming hand cursor still interactive) after you click the mouse button on the level info so you can start the level. I know for a fact that the demo available on one of The One's coverdisks from January 1995 works brilliantly, so I attempted to do file comparisons. Only the executable differed from the two versions, and the TO version was crunched, so I had to unpack it first. Upon unpacking, TO's demo exe weighed in at 142948 bytes, compared to the TOSEC exe's 142944 bytes. Hex-wise, the files aren't dramatically different, with only the sporadic byte changes incurred no doubt as a result of the packing process the TO exe originally went through, though at some point (mainly at the start of the "end of demo" text) the files will veer off one another by just one character, and it stops becoming easy to find major hex changes. I attempted to get around this by editing the TO exe bit-by-bit until the files were more aligned with one another, but despite all this I can't find any significant changes aside from the aforementioned sporadic byte modifications, and I still can't work out why one exe fails and the other performs marvellously. So, if anyone wants to look into it further - by whatever means necessary - then find "Lemmings - Holiday Lemmings 1994 (1994)(Psygnosis)[a].7z" on the EAB file server, and grab the TO version from the above link, and frolic away! (Of course, if navigating the server is too much bother, I could zone up the two versions if there are enough requests. )

01 November 2010, 19:03	#17
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,519	Black screen is CORRECT behavior on a 68000! It requires 68020 or "non compatible 68000". EDIT: Compatible = includes address error exception checks (more work to do), non compatible = ignores address errors = faster. Last edited by Toni Wilen; 01 November 2010 at 19:11.

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31 October 2010, 09:40	#2
mai Registered User Join Date: Feb 2008 Location: Federativnaya Respublika Germaniya Posts: 4,994	...at least A1200 works fine here.

31 October 2010, 15:46	#4
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Strange. An AGA-only demo? That doesn't sound right somehow. Lemme check anyway.

31 October 2010, 17:06	#5
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Okay, what it seems to boil down to is processor. The demo will not work correctly on anything below a 68020. On a 68000 the "freeze on black screen" bug occurs. On a 68010 it won't even get past the initial opening text in the CLI window. On all other processors - including a 68060 - it'll work as intended. Even with JIT and CPU speed cranked all the way up! This surely makes for one fudged up executable if it's been compiled to fail on the earliest Amiga models. Maybe someone with more technical wizardy could explain what went wrong somewhere in the code? Since the 68020 is faster than the 68000, maybe it's a display speed issue.

31 October 2010, 18:24	#7
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Because something obviously had to go wrong in order for a program to lose all 68000/010 compatibility when a similar demo works on all Amigas? People need to know these things in case you get more threads of this calibre again in future.

31 October 2010, 18:33	#8
mai Registered User Join Date: Feb 2008 Location: Federativnaya Respublika Germaniya Posts: 4,994	...thanks for info, [68020] added.

01 November 2010, 13:06	#10
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	I should probably have asked that if anyone happens to own a real 68000 Amiga, then could they test the disk on one to confirm that the problem occurs under real hardware also? Thanks.

01 November 2010, 16:04	#12
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Just zoned it for you, buddy. Even put it in a zip for you in case Amigas still have trouble with the 7z format.

01 November 2010, 16:26	#13
Mad-Matt Longplayer Join Date: Jan 2005 Location: Lincoln / UK Age: 44 Posts: 1,851	This seems to work ok in uae 68000 with ce and mc dissabled.

01 November 2010, 16:29	#14
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,519	I can't see any loading problems. Works until level is supposed to start and then it crashes because it writes longs to odd address (need 68020+)

01 November 2010, 18:49	#16
MethodGit Junior Member Join Date: Dec 2002 Location: The Streets Age: 39 Posts: 2,731	Okay, so here are my findings based on certain settings... 68000, Cycle Exact on (Quickstart A500 default) = freezes on black screen. 68000, Cycle Exact off, More Compatible on = freezes on black screen. 68000, Cycle Exact off, More Compatible off = works! 68010, Cycle Exact on, More Compatible on/off (doesn't really matter) = hangs on opening text CLI screen. 68010, Cycle Exact off, More Compatible on = works! 68010, Cycle Exact off, More Compatible off = works! Say Toni, would you be able to explain why MC would be the one conflicting with the game's code and its performance on certain processors (like, how does it work and what not)? Kinda ironic given its name and all.

01 November 2010, 19:48	#19
fitzsteve Professional slacker! Join Date: Jul 2009 Location: Kent, UK Age: 44 Posts: 6,683	Hey! I guess you guys have it sussed, but anyway I tried on my A600 and in 68k mode it black screens at the start of the level. (Tried both 1.3 and 3.1 Rom) In 020 mode it worked just fine Steve.

08 November 2010, 03:56	#20
Eclipse Turpentine Join Date: Oct 2007 Location: Kent, United Kingdom Posts: 744	There was probably meant to be an AGA version at some point. I'm guessing things might have got mixed up between an AGA and standard demo.

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