I must admit that I am somewhat awed by the fact that a complete stranger would take the time to compose such a detailed and concise response.
You have my sincerest thanks. Del Ventruella ----- Original Message ----- From: "Logan Shaw" <[EMAIL PROTECTED]> To: "Palm Developer Forum" <[email protected]> Sent: Sunday, October 09, 2005 4:31 PM Subject: Re: Databases > Del Ventruella wrote: > > DmCreateDatabase Function > > > 1. Can the ROM emulator simulate a device with a memory card, permitting me > > to use these API calls? > > The emulators and simulators all simulate devices with memory cards, > because all devices have memory cards. > > The terminology is a bit confusing. Do not think of a memory card as > a removable card like an SD Card or a CompactFlash card. A memory > card instead refers to RAM. The Palm OS design supports the idea of > having more than one chunk of RAM in different address ranges. A > hypothetical device might come with some built-in RAM and then have > a slot where you could install an additional card. Since that card > could be in a different address range, the API supports the notion > of multipe different cards. But in reality, this functionality was > virtually never used, and essentially all devices have just one card, > and it is card #0. So just pass 0 for the card number and don't worry > about that parameter. > > Also, the other thing to realize about this is that since a "card" > refers to RAM, your database will be created in RAM. On Palm devices, > the RAM is battery-backed (or on newer devices, it is a cache of data > that is stored on flash), so it can be used as permanent storage. In > fact, when you reset the Palm, the RAM isn't erased, unlike on a > desktop machine. > > > 2. Will these database API calls cease to be functional in the Cobalt OS? > > Yes, they should be. Cobalt also adds some newer, more advanced types > of databases, but the traditional databases that exist now should > continue to be supported. > > > 3. If one is going to create a program that creates large databases, memory > > cards are the way to go? > > A Palm device's RAM is divided (with fixed divisions) into several pieces, > and one of these pieces is used to store database data. This region is > called the storage heap. Most devices have at least 5 or 6 MB of storage > heap, because most devices have 8 MB or more of RAM, and on most devices, > the storage heap takes up most of the RAM. Some of the bigger devices > have a storage heap which is on the order of 50 MB. So, depending on > what you mean by "large", the storage heap might or might not be a good > place to store your data. > > The other alternative is to store it in a file on a filesystem. That > means you'd be storing it on an SD Card on most devices, although some > devices have built-in flash that stores a filesystem. SD Cards are > available in sizes as big as a gigabyte, so if you need to store lots > of data, that might be your best bet. > > > 4. How does one determine the card number (is this a card serial number, or > > a slot designator in the device)? > > As I mentioned above, in practice it's always zero. > > - Logan > > -- > For information on using the PalmSource Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/ > -- For information on using the PalmSource Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
