It's not hard to build programmer for at89c2051 - if You have
some expirience with x51.
Programming model of 2051 is not complicated - see datasheet.
As Mr.Jan Waclawek says - there is no need for LCD.
For debuging You can use serial port.


Use one 89x51 as master/programmer.
Connect P0,P1 to ports of 2051 (maybe trough 100...300 ohm resistors).

There are 3 hardware problems -
- how to power 2051 - Master can conect 5v trough PNP
transistor.
- how to manipulate RST pin of 2051
-- connect RST pin to 5V trough 1...10k
-- connect NPN transistor between RST pin and ground
Master will control this transistor.
In series - 200..500 Ohm resistor for protection
-- connect optron between RST and +12V supply.
In series - 200..500 Ohm resistor for protection
Master will control this optron.
- how to power whole circuit
--Use 12V accumulator (even from car).
--Use Regulator 7805 to produce 5V
--Some LDO regulator circuit for Vpp limits : 11.5....12.5V



Firmware must provide low levels on all 2051 connected pins when
target has to be inserted/removed in/from socket.

Firmware can retrieve binary data from EEPROM chip , or
can include this data.


regards,
Stefan