CRT format for the VIC-20

[eslapion]

no, we will certainly add no magic guessing.

If you think 'magic guessing' is required then you understood nothing.

... no problem at all, since you need a loader anyway.

Where in the hell ??

.. it'd be a bad idea no matter who suggested it.

Every idea is bad if you don't bother making sense of it.

[groepaz]

Where in the hell ??

so how will you load your suggested format into vic20 memory without additional loader? yeah sure, you could have specific hardware to like you suggest - however without such extra hardware you need a loader that puts the data where it belongs. and with the extra hardware you will have to know how to setup the hardware before loading. and thats a terrible idea for emulator - for emulation the fileformat should provide all info that is needed to run the cartridge.

Every idea is bad if you don't bother making sense of it.

and some ideas are just bad.

[eslapion]

so how will you load your suggested format into vic20 memory without additional loader? yeah sure, you could have specific hardware to like you suggest - however without such extra hardware you need a loader that puts the data where it belongs. and with the extra hardware you will have to know how to setup the hardware before loading. and thats a terrible idea for emulator - for emulation the fileformat should provide all info that is needed to run the cartridge.

In the C64 .CRT files, you have codes telling the emulator what to do, what type of cartridge image you're dealing with and there is software components in VICE (or even an Easy Flash cart or 1541 Ultimate cart) that recognize these codes and process the information accordingly.

You are correct in indicating the old unified format was originally intended for RAM expansions with specific hardware added, a very simple one.

But the file format itself acts the same way the codes of a C64 .CRT do. They can tell an emulator or cartridge replicator what to do.

1. It's really a .PRG file with a very specific subset of characteristics. They only load at $2000 or $4000 and they can only be 16386, 8194 or 4098 bytes in size. If they load at $4000 and contain the A0CBM immediately after the loading address then the content of BLK2 should be transferred to BLK5. If they load at $2000 and contain the A0CBM signature at byte 8194 then the content of BLK2 should be transferred to BLK5. The last case is if they load at $4000 but contain no A0CBM signature then they are Scott Adams games.

AFAIK, the above information is as clear as the information codes found in C64 .CRT files.

2. If you don't have the original hardware, you can still load them on most VIC-20s having 16k or more of added RAM. If you load the file to it's intended address and find the A0CBM signature at $4000, transfer the content of BLK2 into BLK5

Code: Select all

FORT=16384TO23575:POKE T+24576,PEEK(T):NEXT

Then turn your expansion to read-only (most 32k-37k expansions have a switch for that nowadays) then SYS64802 (then SYS32592 if you're running a Scott Adams game)

Every idea is bad if you don't bother making sense of it.

and some ideas are just bad.

To prejudiced people, every idea is bad and everyone is wrong no matter how good they may really be.

[beamrider]

If you are using an emulator it's likely to be VICE, in which case you can just load the meg-cart image.

Most users with real hardware asking how to load carts on social media, have no clue about inspecting the A0CBM signature. For these (many of whom have 32K/penultimate etc) I suggest it would be more efficient to convert the cartridge images to 32K prg files with an exomomiser loader that puts them into the right place and runs them?

Such PRGs would also work with FPGA emulators, look at the instructions for MiSTer below, most of it is spent explaining the VIC's cartridge idiosyncrasies.

https://github.com/MiSTer-devel/VIC20_MiSTer

[eslapion]

Most users with real hardware asking how to load carts on social media, have no clue about inspecting the A0CBM signature.

I have absolutely no clue why users would have to do that... the emulator loading the file would have to do it.

[groepaz]

But the file format itself acts the same way the codes of a C64 .CRT do. They can tell an emulator or cartridge replicator what to do.

in a really limited way - which doesnt cut it. how would a megacart image look like in this format? how would the emulator know it must use the megacart hardware for it?

If you don't have the original hardware, you can still load them on most VIC-20s having 16k or more of added RAM. If you load the file to it's intended address and find the A0CBM signature at $4000, transfer the content of BLK2 into BLK5

like i said - a small loader is needed. plus knowledge about the fileformat and cartridges
and as also said - VICE can *already* load combined files. they are different than what you propose - but serve the same purpose.

To prejudiced people, every idea is bad and everyone is wrong no matter how good they may really be.

and that still does not invalidate that some ideas are just bad ideas - no matter how good someone thinks they are.

[eslapion]

But the file format itself acts the same way the codes of a C64 .CRT do. They can tell an emulator or cartridge replicator what to do.

in a really limited way - which doesnt cut it. how would a megacart image look like in this format? how would the emulator know it must use the megacart hardware for it?

As clearly stated above this file format is only for cartridge images limited in size to 16k. Obviously you've never taken the time to read but you already made up your mind.

If you don't have the original hardware, you can still load them on most VIC-20s having 16k or more of added RAM. If you load the file to it's intended address and find the A0CBM signature at $4000, transfer the content of BLK2 into BLK5

like i said - a small loader is needed. plus knowledge about the fileformat and cartridges

Then you'll have to tell me what this loader would do because AFAIK, it's absolutely not needed. Once more, you've made up your mind without knowing.

and as also said - VICE can *already* load combined files. they are different than what you propose - but serve the same purpose.

The format I suggest VICE supports is the only one I know of that was in use in 1981. AFAIK, it's the first one.

[Mike]

@eslapion: PM sent

[groepaz]

Obviously you've never taken the time to read but you already made up your mind.
Once more, you've made up your mind without knowing.

i'll come back when you are ready to discuss technical matters without resorting to ad hominem all the time.

[eslapion]

i'll come back when you are ready to discuss technical matters without resorting to ad hominem all the time.

I clearly specified the proposed format was used strictly for cartridges of no more 16k and only for those published before 1986.

Then you're asking how such a format would support a Megacart image. Clearly there is something that has eluded you here.

It doesn't get any more technical than that.

[Mike]

It doesn't get any more technical than that.

It has been clearly laid out to you, several times here in this thread and in PM, that the file format you propose is not general enough to be sensibly regarded for inclusion into VICE (or any other emulator, for that matter).

Thread closed. It will only be reopened by me, if both parties (groepaz and eslapion) explicitly ask me in PM to do so.