Tutankham - Copy protection or poor programming?

[kevgal]

We cannot consider it a copy protection simply because if you use 8k RAM expansion on BLK5 only, the game works without modifies.

In effect this "issue" is not unusual for BLK5 rom images, I've noticed it by working on the "cheated" version of a lot of cartridge games for the next Mega-Cart revision.

Normally to fix it, I've used the same method suggested by Mike.

Gday guys, I've started converting carts to single file prgs

Which kind of conversion are required?

You may find almost all cart image in PRG format on Zimmers, with 8K RAM on BLK5 just type:
LOAD"BLK5FILE",8,1
SYS64802

or use my CBM-FileBrowser.

PS: you may use also the CBM 8K Expansion by changing dipswitches inside

Gday nbla000, I'm converting these to run as single file PRGs for Retroarch where I can leave the Vice config at full mem expansion without messing around with options and it autostarts the game (although there may be a setting for this in the config? Maybe better ways to pre-set Retroarch Vice configs?). I'm trying to avoid the virtual keyboard as much as possible.
I suspect this may not be the correct forum for this?
In any case the modified CRTs I can use in my multicart without having to mess around with memory switching.
Cheers
Kev

[Mike]

I'm converting these to run as single file PRGs for Retroarch where I can leave the Vice config at full mem expansion without messing around with options [...]

Instead of that, you mess around with the binaries.

Note, VICE can run cartridge images out-of-the-box, given the right configuration options, from the command line.

That is a much preferable option than taking working, original cartridge images and altering them in haphazard ways.

[nbla000]

I'm converting these to run as single file PRGs for Retroarch where I can leave the Vice config at full mem expansion without messing around with options and it autostarts the game (although there may be a setting for this in the config? Maybe better ways to pre-set Retroarch Vice configs?). I'm trying to avoid the virtual keyboard as much as possible.

I've configured retroarch with both retropie on Raspberry Pi 3 B+ and my android phone by using XVIC libretro core configured as VIC-20 PAL Automatic, if I'm not wrong it sets the mem config based on file name for example, for a game that requires 3K just rename it "game [3K].prg", for 16K "game [16K].prg" and for cart i've used "game [A0].prg" and it works without problems but maybe I've done some customizations, I don't remember now, it was just an experiment.

It recognize also file extension .A0 .20 .40 .60 etc etc

[Mike]

But why would you test a value that is in ROM that way? you can just hardcode it, you already know what the MSB is

I don't recall the actual explanation, probably it was a table and so LSR VALUE,X would have been a better example.

Andy Finkel is cited with this remark in Giacomo M. Vernoni's "Commodore VIC-20 A Visual History", on page 123:

There's a rumour that Commodore copy protected its ROM cartridges. I can say, there's no truth to this rumour at all. It's true that if you tried to copy most of them to RAM and run them, they would fail badly, corrupting themselves and crashing if you tried.
But this wasn't copy protection at all... it came from some tricks that I used to do on the 6502 when I wanted to test values in an array without using the accumulator or either index register. By using ROR or ROL on a location in ROM, I could test bit 7 and bit 0 and branch on the results without changing any registers; because the program is in ROM, it would remain unchanged. [...]

Nonetheless, examples of cartridge firmware that deliberately (try to) overwrite themselves exist, RTC V-Link being one of them.

[kevgal]

I'm converting these to run as single file PRGs for Retroarch where I can leave the Vice config at full mem expansion without messing around with options and it autostarts the game (although there may be a setting for this in the config? Maybe better ways to pre-set Retroarch Vice configs?). I'm trying to avoid the virtual keyboard as much as possible.

I've configured retroarch with both retropie on Raspberry Pi 3 B+ and my android phone by using XVIC libretro core configured as VIC-20 PAL Automatic, if I'm not wrong it sets the mem config based on file name for example, for a game that requires 3K just rename it "game [3K].prg", for 16K "game [16K].prg" and for cart i've used "game [A0].prg" and it works without problems but maybe I've done some customizations, I don't remember now, it was just an experiment.

It recognize also file extension .A0 .20 .40 .60 etc etc

Thanks nbla000, I'll definitely try those out.
Cheers
Kev