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Cassette Loads with !


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I have been looking at quite a few cassette programs recently with a view to compiling an XML for MESS. MESS does not have a cassette interface yet but I am preparing for when it does.


Anyway, I have noticed that a few cassette files display an exclamation mark (!) in the lower right of the screen when loading. Is this similar to the "k file" for disk based files. I know the "k" indicates that the disk is not original and is using a loader developed by Ken. Is this the same for the cassette files with the "!" displayed.




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The ! is displayed (by mistake) by one notorious cassette binary loader (the loader has no name, but it is known as "exclamation mark loader.")

Usage of this loader usually indicates one of the following

  • The program was transferred from disk to tape using Nudmehi Software's BOOT CASSETTE MAKER
  • The program was transferred from disk to tape using a utility that has stolen the loader from the Boot Cassette Maker
  • The tape image was created by a utility that runs on PC (XEX2CAS, MagoTrans,...) and also uses the loader


So in most cases, the program is not an original version.

For more information, just google "exclamation mark loader atari" or search atariage forums.

Edited by baktra
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As a side note, I must add that chilean atari fan Franco Catrin did a research on the reason behind the exclamation mark.

He explains that when the loader prints a clear screen character, it does it by executing this code:

765 169 125     LDA #125   ; CLEAR SCREEN
767 32  164 246 JSR PRINT  ; $F6A4

However, the printing routine located on $F6A4 is only valid for 400/800 computers.

On the XL/XE machines, that routine is located somewhere else.

Quote from Mapping the Atari:



Many 400/800 programs made direct jumps to keyboard ‘get’ and ‘put’ routines rather than through the proper vectors, which makes them incompatible with XL/XE machines. The get routines in the XL/XE begin at 62026 ($F24A). This was 63038 ($F63E) in the 800. The put routines begin at 62128 ($F2B0). or 63140 ($F6A4) in the 800. If you have a program which won’t work on your XL/XE, try finding if it uses these locations and change them.


You can confirm this by changing the call from $F6A4 to $F2B0.

The result is that the loader will clear the screen instead of printing the exclamation character.


Source (in spanish):




Kind regards,


Louis BQ

Edited by lbaeza
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