Alfredo states:
Connect the LED cathode to the port pin and the LED anode to +5V via a 1k5 resistor. So yu get about 2 mA. Not very bright and the output current is at its limit value. Valid for test purposes. With
an 89C2051 you can use a resistor of about 330 ohm and get about 10 mA, valid for a real project.
That value is derivative dependent


Shahzad wrote:
- the hex file i downloaded from the internet is working both on 89c2051 and 89c51.

- the LED blinking program i wrote is working on 89c2051 but not on 89c51.

One program (downloaded) works, another (home compiled) does not - compiler or program, not hardware.

Erik