I do not know exact PICBasic syntax but i guess that it is PulseOut. Anyway, you have to set D0 low for some time to send a zero nd D1 low for the same time to send one.
Both data lines must not be low simultaneously.
Card readers output data in 26 bit's where 1-st and last bits are for parity and remaining 24 bits represent some hex numbers. This way you can store many numbers. If you have to send ASCII symbols, for example, you are limited to only 3 characters (24 bits makes 3 bytes)! That's why i used a "pseudowiegand" format.