dvIceT
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Registered: Dec 2000
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Posts: 152 |
quote: Originally posted by argent
PiDirect will not run programs directly from the memory card. That's not possible. The memory on the CF or SM card is not accessible from the Visor. Let me repeat that. The memory on the card is not accessible from the Visor.
PiDirect will have to do what AutoCF does, and copy individual records from the card when they're "locked" by the application. "Locking" a record is the equivalent of "reading" a block from a file on a conventional OS.
For efficiency, they will probably create a cache of a few hundred K, so that when you request a record in cache it will not be copied in again.
Since applications lock all the code records for a program when it's launched (otherwise they could move around as the program modifies databases), launching a program will effectively load the whole program in.
So, basically, the only time you'll be hitting the actual CF or SM card is when you read new database entries, or when you do a search on a large file.
Question for PI: could you verify whether my speculation about cache is correct?
What you say about running programs directly from the memory card is true, in the same way that PC's do not run programs directly from the hard drive. I think we have different understandings of what AutoCF does though. My understanding is that AutoCF works similarly to PC's in that needed code is read off the external memory device on an as-needed basis, put into RAM, then accessed by the processor. The difference between PC's and the PalmOS device, is that by and large, the PC can put far greater amounts of code into live RAM, than the PalmOS device can. Even if it does turn out that whole applications need to be copied into handheld RAM, the ability to offload databases(especially large ones) to external memory will be a godsend (for the lucky ones). 
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