Cassette games

Discuss the games, programs, utilities... and vaporware!
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RayXambeR
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Cassette games

Post by RayXambeR » Sun Nov 24, 2013 10:24 am

I have seen there is audio files on this site. Do I understand that if I can use these file on a cassette and use it in the cassette CV player, I can play these games (some of them are exclusive and not exist in cart format)? Do you think it would be possible th place them on a cartridge? It could be a good idea to publish a cart containing all cassette exclusive games :) It is just an idea ;)
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Mobsie
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Re: Cassette games

Post by Mobsie » Sun Nov 24, 2013 10:38 am

the first point must answer Luca, i have never used my cassette player to play games. I only test the demo tape, thats all.
But your idea with ALL cassette games on a cartridge is very nice and from the software side no problem. We store all in packet format, like i o with my graphics and sound, then a nice menu software and have :D
But from the hardware side is an question to Tom who try to make the first homebrew cart, like we have for the ColecoVison etc.
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MADrigal
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Re: Cassette games

Post by MADrigal » Sun Nov 24, 2013 6:52 pm

Cartridge games are loaded into the "cpu RAM".

Cassette games are loaded into the "video RAM". It's the BASIC's task to load data from a cassette, and then store it to the video RAM, using peculiar routines.

I have an idea about how to store listings on a ROM, but it's very hard to apply to this specific case, because the ROM wouldn't have enough space to fit the listing *and* the BASIC interpreter.

BASIC interpreter is 12 KBytes but it actually fits around 24 KBytes in the cpu RAM map.
The listing could be up to 9 KBytes.
Total: 33 KBytes.
The maximum ROM space available to CreatiVision is 32 KBytes.

My idea would be:
- adding a single BASIC listing to the BASIC ROM program
- adding a routine to the BASIC, which is executed automatically at boot time
- the routine would take data (listing) from the ROM and copy it into the video RAM.

But you could save 1 only listing at a time, on a separate ROM program.

Not useful at all.
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Mobsie
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Re: Cassette games

Post by Mobsie » Sun Nov 24, 2013 7:36 pm

i made a test with basic and put a small listing inside. i change the start jump to a small routine from me. here i copy the listing to the vdp and set the needed vars
then jump to run.

if we made a a cart like this we can use all the space which take the basic commands we don`t no longer need for example the cload , csave , crun etc.
also the line editor we can use. the listings will then be packet, my de-pack ask routine for example is VERY small.

With this is possible to make cart with some interesting listings inside and a small menü with maybe only numbers, you then press 1 for listing 1, 2 for listing 2 etc.
but if someone has interest on this, i don`t know.
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carlsson
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Re: Cassette games

Post by carlsson » Mon Nov 25, 2013 9:14 am

Well, if you need a cartridge anyway, why not stick with Basic and then have TOM make adapters for the Commodore 1530, which are plentiful? Or if you want to take it one step further, either a bit-banging SD interface or even a serial connection to a PC that lets you load a program directly into the VRAM?

For that matter, I'm sure the Basic listings can be compressed a lot, given they are stored as ASCII. The routine to unpack them into VRAM should not take very much space, so you could fit more listings in one cartridge if you go ahead with a custom cartridge containing both Basic interpreter and listings.
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