Hi Andy,

there is no harddisk inside the micro and the only way
to store a program was to burn it into the micro like into
an EPROM.
Many universal programmers can burn EPROMs
and also micro controllers.

Also now some newer micros can be ISP (in system program)
or IAP (in application progam).
Then you need only some connections to the serial
or parallel port and the burning software.

You must look at the data sheet of your micro, how it
can be programmed.

Please watch, that some micros can only be programmed
1 time (OTP), since they can not be erased.

Your compiler give you the executable program as hex file,
which was the common input format for all programmers.

An example of a self made low cost micro programmer
can you see at:
http://www.specs.de/~danni/to.../index.htm


Peter