| ??? 11/15/07 16:14 Read: times |
#147024 - ??? Responding to: ???'s previous message |
Mike Stegmaier said:
Andy Neil said:
The bootloader simply loads the image into memory - then runs it;
not quite. a bootloader (in similest terms) is a piece of software that runs first before any OS starts. You mean, "runs first before any other software starts". A bootloader could (and, on an 8051, often does) load the application with no OS. Andy, do you mean "the computer" instead of "Bootloader"? OK, to be pedantic, I mean: The bootloader is a piece of software that allows the system to load its main software That "main software" could be the complete application (most likely for an 8051), or an OS that will then have further facilities for loading and running applications. Remeber that x means external. so xdata = external data. That was its original meaning way back with the very first 8051 from Intel. Nowadays, "XDATA" may or may not be physically external to the chip - or there may even be some XDATA inside the chip, and some outside. If you need to define a lot of values, use bits. That just makes no sense at all! If you need single-bit values ("flags" or whatever), then remember that the 8051 has facilities to manipulate bits, and has an area of bit-addressable RAM... If that doesn't work, you could try to compress your variables. We already know that the OP is short of CODE space - so adding extra code for data compression is not a good idea! He has plenty of XDATA RAM space - he just isn't using it! |
