write b0,b0 ' writes the value in b0 to the location in EEPROM with the address in b0 (but note that the first b0 is the address and the second is the value to be written)
Not the "RAM contents of b0" (in normal terminology), but the value of b0 to the address in EEPROM corresponding to that value, so that when b0 is 0, zero gets written to EEPROM address 0, then 1 gets written to EEPROM address 1, 2 gets written to EEPROM address 2, etc. through value and address 10.
Then the second loop reads the values at EEPROM addresses 0-10 sequentially into b1, and prints that value with sertxd.
The second loop has no WRITE command in it, so it doesn't alter the contents of the EEPROM--it just reads the stored values and prints them.
b0 technically +is+ RAM (that is, volatile memory whose contents will be lost upon power-off), but we would generally think of it as a variable. That variable is at RAM address 0, so "BPTR=0: SERTXD(@BPTR)" would print the value of b0, just as SERTXD(b0) would.
I'm not sure that I answered all of your question--please ask again for additional clarification.
Note that geoff07's caveat holds--if you reprogram the chip and don't include the directive, "#no_data", everything that you have previously written to EEPROM will be zeroed out. If you include "#no_data", the contents of EEPROM will be preserved.