They Stole a Million
I noticed that the tzx on the site is missing a Speedlock Block for Part 2. I don't own the original so cant make a perfect tzx, but I did recreate the missing speedlock block from the TAP version.
It was interesting to learn how a simple Speedlock 2 block works, steps were...
1) recreate the encryption. Speedlock is doing LD A,69 XOR (HL) ADD A,239 so I did SUB 239 LD B,A LD A,69 XOR B to make the encryption
2) recreate the check byte. By XORing all the encrypted bytes together.
On the original tape, I think there must be no gap between the 2 blocks for part 2, as part of the 2nd clicking leader is "attached" to the end of the data stream of the existing first block, anyway I put a second gap between them.
Maybe someone could make a perfect TZX but in the meanwhile here's mine:-
http://nugget.no-ip.biz/spectrum/stoleamill.zip
Have a great day!
It was interesting to learn how a simple Speedlock 2 block works, steps were...
1) recreate the encryption. Speedlock is doing LD A,69 XOR (HL) ADD A,239 so I did SUB 239 LD B,A LD A,69 XOR B to make the encryption
2) recreate the check byte. By XORing all the encrypted bytes together.
On the original tape, I think there must be no gap between the 2 blocks for part 2, as part of the 2nd clicking leader is "attached" to the end of the data stream of the existing first block, anyway I put a second gap between them.
Maybe someone could make a perfect TZX but in the meanwhile here's mine:-
http://nugget.no-ip.biz/spectrum/stoleamill.zip
Have a great day!
Post edited by nuggetreggae on
Comments
I checked my notes I made when trying to convert one of my copies and I think I just got fed up with it because MAKETZX converts the first two Speedlock blocks ok and then ignores the third. Or something like that. It may explain why the WOS one is missing a block. I think I tried editing one out to see if it would convert properly then but my notes were a little vague.
If a game loads ok from the sample but starts becoming too much of a hassle to convert to TZX I tend to file it under "to do when I've run out of tapes". This was one of those games.
Anyway, I've uploaded a sample in case anyone wants to have a look at it and compare it against nuggetreggae's clever reverse engineered version. At the very least, the gap either side of the block can be adjusted if necessary.
https://db.tt/2qehFIgg
Can makeTZX not just convert the 1 missing block then paste it in using ZX blockeditor? Obviously it wasn't designed to handle all of them at once..... although beach head also has 4 blocks and thats perfect....