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PostPosted: Fri Oct 28, 2011 11:02 am 
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Hi,

I'm sure this has been talked about before - but I couldn't find the post.

Anyway I have my Mode7 program at $6000 and want to *LOAD a large data file in at $1900 and then do a *TAPE and relocate it downwards. Unfortunately the file is so long it will overwrite my program.

If I *LOAD it in at $1000 things would be ok - I can test this but I don't have a real BBC-B and was wondering how reliable this would be anyway.

Is there a breakdown of how the DFS uses $D00-$1900?

Also if I'm not using sound or key definitions I can use the memory at $400-$CFF right?

Can I *LOAD a file directly into $400-$CFF and as long at I leave $D00-$1900 alone the DFS will continue to function ok?

- PJ


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PostPosted: Fri Oct 28, 2011 12:02 pm 
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$400-$CFF should be okay I think. The lowest you can normally load is $1100.


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PostPosted: Fri Oct 28, 2011 8:08 pm 
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All the detail's at MDFS: http://mdfs.net/Docs/Comp/BBC/Disk/DFSMem

In essence, as long as you're careful you can *LOAD into &1400, or maybe even &1300 - but I'd make sure that you make sure that the *LOAD is the only disc access and that all other file handles are closed.

You can use DFS to load anywhere in memory - though it'll corrupt the data if you touch between &e00 and &1400. (In theory you may even be able to overwrite &e00 to &fff - as this is just a copy of the current directory, but you may want to try this out first!)


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PostPosted: Fri Oct 28, 2011 10:37 pm 
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You can safely load at $1100. *LOAD doesn't use the open file buffers, so you can safely overwrite them.


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