Definitive list of games incompatible with +2A/+3 and of compatible versions (if any)

[Alessandro]

@amazin, I looked into the code and found the problem - a classic case of incompatibility with the +2A/+3 ROM of the I register set as IM2 vector at address 14847 (39FFh). Changing the byte value at address 40005 from 57 to 59 solved it for both titles. Fixed files will follow soon.

[Ast A. Moore]

Alessandro beat me to it.

I made a fix earlier and only just now got home and uploaded Kidnap to my website.

[amazin]

Brilliant stuff, thanks Ast, thanks Alessandro.

Here it is, running on the real hardware



Thanks ever so much for your effort in demistifying that the +2A/+3 are inferior machines.

Thanks again.

[Ast A. Moore]

Nice! Kudos for the Maxell tape in the Datacorder.

[Alessandro]

The fixes have been put on the website.

Just one word of caution, both games should be loaded under 48 BASIC, otherwise the keyword SPECTRUM will appear all across the starting screens and kill the playing character upon impact, making them unplayable.

[amazin]

Nice! Kudos for the Maxell tape in the Datacorder.

AHHAH Thanks, they are indeed really good. I'm not an expert, but I got some Maxell, some Sony, some TDK.

Actually it is quite hard nowadays to find 60 minutes tapes. 90 minutes are more common.

[Ivanzx]

Seems like Scaramouche is also incompatible with the +2A, as even being loaded in 48K mode the game would not start, screen freezes in the 1st stage:

https://spectrumcomputing.co.uk/entry/1 ... caramouche

Would there be an easy way to fix it, via Poke entered in the loader?

[Alessandro]

@Ivanzx, Scaramouche seems to be incompatible with the 128/+2 as well.

The game hangs here:

Code: Select all

25254  LD A,(BC)
25255  LD E,A
25256  ADD HL,DE
25257  INC BC
25258  LD A,C
25259  CP 128
25261  JR NZ,25254

It seems the value of C and therefore of A after the LD A,C instruction is never equal to 128, so the conditional jump at location 25261 is executed in an endless loop.

Interestingly, if you load and run The Ghost before the game, it will work as expected.

[Ivanzx]

@Ivanzx, Scaramouche seems to be incompatible with the 128/+2 as well.

The game hangs here:

Code: Select all

25254  LD A,(BC)
25255  LD E,A
25256  ADD HL,DE
25257  INC BC
25258  LD A,C
25259  CP 128
25261  JR NZ,25254

It seems the value of C and therefore of A after the LD A,C instruction is never equal to 128, so the conditional jump at location 25261 is executed in an endless loop.

Interestingly, if you load and run The Ghost before the game, it will work as expected.

Thanks, Alessandro for the confirmation.

Wow, this Ghost is such a discovery, isn´t it?? :O Theoretically will enable all the incompatible games work??

By the way, I am going to type it up and save it to one cassette, but there are 2 listings... Do I have to type them and save them separatedly one after the other?

[Alessandro]

@Ivanzx : The Ghost is a bit of a hit-and-miss, but in this case it proved itself to be useful.

There is no need to follow the original instructions if you just wish to use it on real hardware. You can play the second and third block from the TAP file - the BASIC and machine code blocks - with a utility like Tapir and save them to a tape connected to your PC through the usual 3.5 mono cables. Start recording, then open the GHOST.TAP file in Tapir, highlight the "Prog: GHOST" header, select Block > Play from cursor and wait a few seconds until playback has stopped.

That is, until someone more expert than me in the exoteric art of understanding Z80 machine code comes up with a permanent solution...

[Ivanzx]

@Ivanzx : The Ghost is a bit of a hit-and-miss, but in this case it proved itself to be useful.

There is no need to follow the original instructions if you just wish to use it on real hardware. You can play the second and third block from the TAP file - the BASIC and machine code blocks - with a utility like Tapir and save them to a tape connected to your PC through the usual 3.5 mono cables. Start recording, then open the GHOST.TAP file in Tapir, highlight the "Prog: GHOST" header, select Block > Play from cursor and wait a few seconds until playback has stopped.

That is, until someone more expert than me in the exoteric art of understanding Z80 machine code comes up with a permanent solution...

Hi Alessandro, unfortunately, I don´t have the knowledge and equipment you mentioned, so for me it is easier to do it in the old way, typing the program and saving it in the cassette

It is also interesting what you mentioned about the program being a hit and miss, will try it with many games, to see how it works out

Anybody could tell me if typing and loading the 2 listings of The Ghost is the right way?

[jpnz]

Courtesy of the other forum, you can add The Rats to the list

I have a fix - will post about that after some more testing

[Alessandro]

Thanks @jpnz, will wait for news from you then.

[Bolton80]

Courtesy of the other forum, you can add The Rats to the list

I have a fix - will post about that after some more testing

It was me who queried this on the other forum. Thank you for picking this up. Will look forward to seeing if you can provide a fix. I was a massive James Herbert fan but didn't know the game existed until I spotted it on eBay a couple of weeks ago.

I've got a DIVMMC Future on it's way to me, so a TAP version would be ideal (as far as I know TZX won't work on these devices?)

I'm quite out of touch to be honest. I've only just re-purchased a Spectrum after selling my whole collection dirt cheap about 20 years ago... I regret that now!

[goodboy]

@Ivanzx, Scaramouche seems to be incompatible with the 128/+2 as well.

The game hangs here:

Code: Select all

25254  LD A,(BC)
25255  LD E,A
25256  ADD HL,DE
25257  INC BC
25258  LD A,C
25259  CP 128
25261  JR NZ,25254

It seems the value of C and therefore of A after the LD A,C instruction is never equal to 128, so the conditional jump at location 25261 is executed in an endless loop.

Alessandro, you're a little bit wrong.
this piece of code counts the checksum of memory in the range (#0000- #007f) and then checks it with the template at 25267.

[goodboy]

Courtesy of the other forum, you can add The Rats to the list
I have a fix - will post about that after some more testing

#FB8F LD A,#39 ; vector to IM2

[Alessandro]

Thanks for the clarification @goodboy.

I examined the code running on Spectaculator and noticed it was endlessly repeating this part, so I thought that the CP 128 operation never returned a value of zero, thus making the program counter continuously jumping back to 25254.

[jpnz]

It was me who queried this on the other forum. Thank you for picking this up. Will look forward to seeing if you can provide a fix. I was a massive James Herbert fan but didn't know the game existed until I spotted it on eBay a couple of weeks ago.

I've got a DIVMMC Future on it's way to me, so a TAP version would be ideal (as far as I know TZX won't work on these devices?)

I'm quite out of touch to be honest. I've only just re-purchased a Spectrum after selling my whole collection dirt cheap about 20 years ago... I regret that now!

Fix is tested and ready!



Download is here - includes TAP, TZX and source code

Just load in the TAP then playback the game tape

A note about the strange loader from the Crash review

While the game is loading it is easy to believe that an error has occurred the tape error warning used in the sequence is totally useless and it's difficult to tell whether the program is being received. This problem is aggravated by the disablement of the speaker, and for some totally inexplicable reason, some of the blocks are not actually received at all, to judge by the border during loading. It is natural to assume that the system has crashed but if you leave well alone, the game loads perfectly in the end. This weird pretence of failing to load is very annoying particularly since it isn't referred to in the instructions. Very unfriendly.

#FB8F LD A,#39 ; vector to IM2

Yup, that's exactly it - alter the interrupt vector to 0x3B and we're good

[Bolton80]

Fix is tested and ready!



Download is here - includes TAP, TZX and source code

Just load in the TAP then playback the game tape

A note about the strange loader from the Crash review





Yup, that's exactly it - alter the interrupt vector to 0x3B and we're good

Thank you! Looking forward to playing this. Out of interest, is there a way to combine the patch and Rats TAP file into a single TAP file, just for convenience?

[jpnz]

Thank you! Looking forward to playing this. Out of interest, is there a way to combine the patch and Rats TAP file into a single TAP file, just for convenience?

Sure thing, TAP/TZX with patch inserted is here

[Alessandro]

Thank you @jpnz

The correction has been added to the list.

Now, if someone more knowledgeable than your humble writer could take a look at that issue with Scaramouche...

[goodboy]

to game "Rats"

A note about the strange loader ...

try remove POP HL at 27290 ; change to NOP
the game creates a random script so not all episodes are loaded
.............
and there is also a save/load current state of game.
s/s+S or L on map screen

[Bolton80]

Sure thing, TAP/TZX with patch inserted is here

Thank you jpnz. Great work

[goodboy]

Now, if someone more knowledgeable than your humble writer could take a look at that issue with Scaramouche...

Alessandro, check your email

[Alessandro]

Already done

Thanks to @goodboy, a cure has been found for Scaramouche, and has been added to the list.