How Do you Go About Converting a TAP to PRG?

[Pedro Lambrini]

TAP files are great for the sake of preservation but they're a pain in the neck when it comes to modern storage devices as used on a real VIC. The most common and affordable modern storage solutions (SD2IEC and uIEC)can't even do anything with them...

I would love to start converting some TAP only games to PRG but I haven't a clue how to do it. I've tried messing around with the likes of WAV-PRG and TAPclean but I haven't really worked anything out as yet.

What kind of knowledge do I need to embark upon this project? Is it even possible for someone as ignorant as me to learn!?

[eslapion]

TAP files are great for the sake of preservation but they're a pain in the neck when it comes to modern storage devices as used on a real VIC. The most common and affordable modern storage solutions (SD2IEC and uIEC)can't even do anything with them...

I would love to start converting some TAP only games to PRG but I haven't a clue how to do it. I've tried messing around with the likes of WAV-PRG and TAPclean but I haven't really worked anything out as yet.

What kind of knowledge do I need to embark upon this project? Is it even possible for someone as ignorant as me to learn!?

Many TAP files have to stay in that format because the original games either use a tape accelerator or some form of copy protection.

Unless the game has no protection, the type of conversion you want to do is more or less a matter of cracking the software you want to convert.

It is quite normal that SD2IEC and uIEC can't do anything with these as these devices are substitutes to disk storage device which use a completely different type of data transfer.

In other words, how you go about converting a TAP to a PRG is a case by case matter and it is VERY complicated, most of the time.

[Boray]

You can try the buttons "Save as" and "Next" in PRG Starter. That can help you extract the files at least.

[Mike]

Pedro,

Unless the game has no protection, the type of conversion you want to do is more or less a matter of cracking the software you want to convert.

just to give you a small hint at what is involved in this:

- one would at first simply load in the game as normal, checking the type of the autostart and fastloader involved (if any),

- the next big issues: what parts of the RAM are actually used? Could it be saved as one-filer? Is there an identifiable start-address? [1] Does it rely to be started from an 'unmodified' state?

- normally the goal is to prepare the game in a state in memory, as if it had just been loaded from tape, but has not yet been 'started'.

- the next step: inhibit the autostart(ing fastloader), and instrument its code so it just loads the game, but doesn't start it - rather writes a memory dump to disk,

- as final step, write a loader/intro for the memory dump, which then starts the game, or use a packer to compress the memory dump which then quite as well starts the unpacked dump at the start address.

A lot of copy protection measures went a long way to keep the cracker from saving that raw memory dump to another medium. Nowadays, with VICE and its built-in monitor it's not so difficult anymore, but you still need a good lot of programming experience.

Michael

[1]: you'd usually look for code which initialises the stack, the video chip registers, sets up interrupt vectors etc., like 'SEI, LDX #$FF, TXS' ...

[tlr]

Copy protection methods seem to be far less developed on the Vic-20 than on the c64 though.

The protected games usually just rely on what is loaded in the tape buffer and sometimes the screen contents. They also fill most of the memory to make it more difficult to transfer.

I have rarely encountered any custom fast loaders.

You can try this to get the initial dump: raw tape transfer 1.1

[Mayhem]

I'll also chime in:

- if the game is more than one-parter, even if the game section is one load, there might be data loaded in from the previous part that the game uses.

TLR's program is pretty handy, and I've been able to use it to transfer a few games so far that fall into the constraints (single load, unexpanded).

@TLR - if you want to see a custom fast loader, I believe the Anirog release of "Jump Jet" uses one. It's 16K and yet doesn't go past about 27 on the counter. Unless it's that small code wise and needs all the memory for processing.

[eslapion]

I have rarely encountered any custom fast loaders.

Sink your teeth in the tape version of paratrooper.

[tlr]

@TLR - if you want to see a custom fast loader, I believe the Anirog release of "Jump Jet" uses one. It's 16K and yet doesn't go past about 27 on the counter. Unless it's that small code wise and needs all the memory for processing.

I have rarely encountered any custom fast loaders.

Sink your teeth in the tape version of paratrooper.

I'd love to see those, where do I get them (as .tap)?

[Mike]

Sink your teeth in the tape version of paratrooper.

Or the tap of Las Vegas 20 (for +16K VIC-20), from which I could extract a single file *.prg some years ago.

tlr, if you are also interested in this one, just PM me your e-mail address.

[Mayhem]

Jump Jet is in GB20, as I made the TAP from my own original.

[tlr]

Jump Jet is in GB20, as I made the TAP from my own original.

Aha, where do I get it? I only found v0.2 on Roberts site and Jump Jet doesn't seem to be in it. Maybe I missed something?

[tlr]

Code: Select all

    1 print"{clr}anirog cracker / tlr":print
    2 print"insert original and";
    3 sys63407:print"loading..."
    4 poke913,44:poke916,44
    5 poke929,116:poke930,196
    6 sys849

download: anirog_cracker.prg

Load original tape using above program and then save.
Worked on Flight Path 747 and Las Vegas. Others?

[Mayhem]

Jump Jet will be in v0.3 coming out shortly. I thought I may have uploaded it somewhere first too... or maybe not. Have to check.

[Pedro Lambrini]

Bugger. Well, this is certainly out of my league! Thanks for all the replies though.

[Mayhem]

Yeah, if it was fairly easy, I'd be doing it to populate parts of GB20...