Code:
@ device pic12F519, intrc_osc, wdt_off, mclr_off, ioscfs_on, protect_off, cpdf_off
option_reg=$80 : tmp var byte : tmp2 var byte : ledtmp var byte
badflag var bit : trisb = $3c : portb=0 : led var portb.0
main: badflag = 0 : for tmp=0 to 63 : write tmp,tmp : pause 10 : read tmp,tmp2
if tmp<>tmp2 then gosub flashbad
next tmp : if badflag = 0 then gosub flashgood
goto main
flashbad:  badflag = 1 : for ledtmp=0 to 9 : led=1 : pause 50 : led=0
pause 50 : next ledtmp : return
flashgood: for ledtmp=0 to 9 : led=1 : pause 500 : led=0 : pause 500
next ledtmp : return
end
Code will write the value into the eeprom location, then read it back, stepping thru each eeprom location in the '519.
If the readback doesn't match what was written, the led will flash fast 10 times.
If the readback is good, it'll flash slowly 10 times after the loop is complete, then start over...