BobG,

        Thanx... It makes sense to me now, I think I remember reading something in
the spec sheets for the '877 on Microchip's web site about this...

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Robert E. Griffith
Sent: Wednesday, July 25, 2001 7:03 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: Bootloaders?


Some PICS with Flash memory like the 16F877 can program themselves, without
the aid of programming hardware (low voltage programming).  A bootloader is
a small PIC program that resides at the top 256 bytes of program memory.
The reset vector points to it.  When the device resets the bootloader
executes and determines if there is new firmware waiting to be delivered on
a serial port or other comm channel. If it is, it downloads it into the rest
of the program memory. If not, it jumps to the normal program entry point.

A common configuration is to have a program on your PC platform that uses
the serial port to transfer a new program to a device over a serial port.

--BobG

-----Original Message-----
From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On
Behalf Of James Burkart
Sent: Wednesday, July 25, 2001 4:31 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: Bootloaders?

I've been messing with pics for a while. I have heard the term 'bootloader'
but am not familiar with what it is or the reason someone would need it in
the first place? Can anyone suggest any source of info that I may learn a
little more about these things?

Thanx...

James Burkart
jamesburkart@yahoo.com

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