Wriggler on ZX Spectrum+2 - UK Vintage Radio Repair and Restoration Discussion Forum

raystav · 9th Oct 2015, 11:07 am

Hi

I have just bought a ZX Spectrum + 2 which plays all games except Wriggler.

I bought another Wriggler tape but that won't load either.

Please help.

I used to love that game.

Ray

Courtney Louise · 9th Oct 2015, 12:41 pm

There were definite inconsistencies between an original ZX Spectrum 48k and a Spectrum +2, does the Wriggler box state it is +2 compatible?

richrussell · 9th Oct 2015, 4:19 pm

Wriggler was released in 1985, so just predates the +2 by about a year. Is it that it won't load, or that it crashes as soon as it finishes loading? I've only ever run it on a 48, 128 and emulators.

It's one of my favourite Spectrum games too

The graphics were all drawn by an 8 year old Allin Kempthorne who went on to become an actor in the Harry Potter films amongst other things.

SiriusHardware · 9th Oct 2015, 6:19 pm

Is this the grey 'Amstrad' Spectrum +2, which comes up with an 'Amstrad 1986' copyright message in 48K mode instead of a 'Sinclair 1982' message?

If so, that could be the reason why. That (and possibly other changes) to the original 16/48K ROM caused no end of trouble, the reason being that a lot of copy protection schemes worked by using the ROM data to encode (XOR, etc) the data onto tape originally, and then doing the reverse when the code was being loaded back in from tape. It was a way of ensuring that the game could only be loaded on a machine with an unmodified ROM.

Why would they do this? Well, the presence of a modified ROM meant that possibly something else, such as a hardware 'snapshot' type copy device, was present.

Unfortunately, Amstrad's unnecessary 'vanity' change to the logo (and possibly other changes) meant that a few bytes of the newer ROM were different to the original Sinclair version of the ROM, and it broke a lot of loaders.

Borrow a rubber-key Spectrum to check your tapes first.

If they work, if you are handy with an eprom programmer you could try reading the +2 ROM, overwriting the 16/48K portion of the ROM with the exact code from an original 16/48K Spectrum and writing it to an equivalent EPROM to see if that fixes the problem.

julie_m · 10th Oct 2015, 2:18 am

Ah, yes, the hackery that even we mere mortals can do with modern computers, as compared to all that was available at the time!

Try experimenting with running the game in an emulator (just use your favourite search engine). There are some games that require a more strict "48K" mode than the slightly imperfect emulation afforded by the +2, whose extra hardware sometimes gets in the way of certain programming techniques that simply aren't expecting it to be there. If a memory snapshot taken in "real 48K" mode will run in "Plus 2 48K" mode, then you should be able to make a tape of that and play it on the real +2.

julie_m · 11th Oct 2015, 12:01 am

UPDATE: I downloaded a .tzx of the game and it ran successfully under the FUSE emulator in "48K" mode. I then tried it in "Spectrum +2" mode, and it seemed to run successfully in that mode.

What are the actual symptoms when you try the game on your Spectrum +2? If it's too complicated to put into words, can you upload a video onto YouTube (most modern phones can do this straight from a "share" menu in the camera app) and post the link here?

9th Oct 2015, 11:07 am	#1
raystav Retired Dormant Member Join Date: Oct 2015 Location: St Ives, Cambridgeshire, UK. Posts: 1	Wriggler on ZX Spectrum+2 Hi I have just bought a ZX Spectrum + 2 which plays all games except Wriggler. I bought another Wriggler tape but that won't load either. Please help. I used to love that game. Ray

9th Oct 2015, 12:41 pm	#2
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,328	Re: Wriggler on ZX Spectrum+2 There were definite inconsistencies between an original ZX Spectrum 48k and a Spectrum +2, does the Wriggler box state it is +2 compatible? __________________ *33, 45, 78, around and around they go...*

9th Oct 2015, 4:19 pm	#3
richrussell Heptode Join Date: Jul 2008 Location: Selby, North Yorkshire, UK. Posts: 979	Re: Wriggler on ZX Spectrum+2 Wriggler was released in 1985, so just predates the +2 by about a year. Is it that it won't load, or that it crashes as soon as it finishes loading? I've only ever run it on a 48, 128 and emulators. It's one of my favourite Spectrum games too The graphics were all drawn by an 8 year old Allin Kempthorne who went on to become an actor in the Harry Potter films amongst other things.

9th Oct 2015, 6:19 pm	#4
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,586	Re: Wriggler on ZX Spectrum+2 Is this the grey 'Amstrad' Spectrum +2, which comes up with an 'Amstrad 1986' copyright message in 48K mode instead of a 'Sinclair 1982' message? If so, that could be the reason why. That (and possibly other changes) to the original 16/48K ROM caused no end of trouble, the reason being that a lot of copy protection schemes worked by using the ROM data to encode (XOR, etc) the data onto tape originally, and then doing the reverse when the code was being loaded back in from tape. It was a way of ensuring that the game could only be loaded on a machine with an unmodified ROM. Why would they do this? Well, the presence of a modified ROM meant that possibly something else, such as a hardware 'snapshot' type copy device, was present. Unfortunately, Amstrad's unnecessary 'vanity' change to the logo (and possibly other changes) meant that a few bytes of the newer ROM were different to the original Sinclair version of the ROM, and it broke a lot of loaders. Borrow a rubber-key Spectrum to check your tapes first. If they work, if you are handy with an eprom programmer you could try reading the +2 ROM, overwriting the 16/48K portion of the ROM with the exact code from an original 16/48K Spectrum and writing it to an equivalent EPROM to see if that fixes the problem.

10th Oct 2015, 2:18 am	#5
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Wriggler on ZX Spectrum+2 Ah, yes, the hackery that even we mere mortals can do with modern computers, as compared to all that was available at the time! Try experimenting with running the game in an emulator (just use your favourite search engine). There are some games that require a more strict "48K" mode than the slightly imperfect emulation afforded by the +2, whose extra hardware sometimes gets in the way of certain programming techniques that simply aren't expecting it to be there. If a memory snapshot taken in "real 48K" mode will run in "Plus 2 48K" mode, then you should be able to make a tape of that and play it on the real +2. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

11th Oct 2015, 12:01 am	#6
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Wriggler on ZX Spectrum+2 UPDATE: I downloaded a .tzx of the game and it ran successfully under the FUSE emulator in "48K" mode. I then tried it in "Spectrum +2" mode, and it seemed to run successfully in that mode. What are the actual symptoms when you try the game on your Spectrum +2? If it's too complicated to put into words, can you upload a video onto YouTube (most modern phones can do this straight from a "share" menu in the camera app) and post the link here? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.