How do exactly works the .CAS Format ?

Thank you very much.

How do you recognize if a file on a tape is a Binary or not?

Now I understand... Thank you very much for your help

This sequence of bytes:

0x1F 0xA6 0xDE 0xBA 0xCC 0x13 0x7D 0x74

is the "header" of your file stored on tape: it tells the MSX that what follows on the tape is not garbage but a program (or at least some valuable data). This is followed by ten bytes that explain to the MSX which kind of file it is going to read. All these ten bytes must have the same value:

if the byte value is 0xD0, then it's a binary file
if the byte value is 0xD3, then it's a basic file
if the byte value is 0xEA, then it's an ASCII file
if the byte value is not one of these three, then the MSX knows that it is going to read a data block. A data block can be used to store data, for example if you'd like to create a turbo loader you could make a binary file first with the program that handles the turbo loading, then you could store the file you want to load in a data block.

you usually could have to handle one of these cases:

1) A BINARY FILE:

* When this byte value is 0xD0, 0xD3 or 0xEA (Binary, Basic or ASCII) this is followed by six bytes / six characters that contains the name of the file.

* After the name of the file you have six bytes that explains to MSX:

- the STARTING ADDRESS; From which RAM address the MSX will have to store data (2 bytes)
- the ENDING ADDRESS; that is equal to STARTING ADDRESS + FILE LENGTH - 1. Just remember that FILE LENGTH is the length of your file *WITHOUT* the header information, just the plain file you're going to load. (2 bytes)
- the EXECUTION ADDRESS; that tells the MSX on which memory address it will found an assembly routine to execute the file. (2 bytes)

REMEMBER: all these addresses (STARTING, ENDING and EXECUTION) takes two bytes *BUT* the byte values are stored "swapped"; this method does have a name and if I am not mistaken it was invented by Intel, but in this moment I cannot remember its name (big-endian and low-endian).
If I show you an example, maybe you'll understand this concept better:

let's say we want to store address 0x4000. In this case we'll have to put bytes 0x00 and 0x40. You swap 40 and 00.
Now let's say we want to store address 0x1234. In this case we'll have to put bytes 0x34 and then 0x12. You swap 12 and 34.

2) A BASIC FILE:

* When this byte value is 0xD0, 0xD3 or 0xEA (Binary, Basic or ASCII) this is followed by six bytes / six characters that contains the name of the file.
* Remember that what follows is a tokenized basic file.

3) AN ASCII FILE:

* When this byte value is 0xD0, 0xD3 or 0xEA (Binary, Basic or ASCII) this is followed by six bytes / six characters that contains the name of the file.
* Every 256 bytes you have a resynchronization (the long "BEEEEEEEEP" sound you hear when you try to listen a msx tape). resynchronization is (again) 0x1F 0xA6 0xDE 0xBA 0xCC 0x13 0x7D 0x74.
* If the length of your program is less than 256 bytes, you should fill it with the value 0x31. I don't know why or if you could use another value, but 0x31 worked for me.

If you want some weeks ago I have started to convert some portions of MSX Taper in PHP, you can read the sample code to read a tape file by visiting this web address:

http://code.google.com/p/msx-tape-tools/source/browse/trunk/msxtape.php

This simple PHP script will read the content of a .CAS file, put it into a XML file and then it will print it on the screen. The indentation of the code is not really good on the site, I probably forgot to use TABs instead of spaces on some lines because it's perfect on my IDE, and the comments are still written in Italian, but maybe you can have an idea about what it does.

Quick question (really old thread i know... but meh)

How do you handle the custom types? CAS2WAV doesn't like these, and it'd be good to put them in (as certain cas files don't work after converting)