About 89c51 Microcontroller

8051 Microcontroller is a programable device which is used for controlling purpose.
Basically 8051 controller is Mask porogramble means it will programed at the time of manufacturing and will not programed again, there is a derivative of 8051 microcontroller, 89c51 microcontroller which is reprogramable upto 10000 times, here is small discription abot the 89c51 microcontroller.
It have 4 ports which are used as input or output according to your need.
These prots are also programmed as bit wise pattern, means you can use each bit of microcontroller saperatelly as input or output.
This 89c51 is 8-bit device mean each port have 8-bits for I/O, total of 32-bits in the controller.
This device also have Timer, Serial Port interface and Interrupt controlling you can use these according to your need.
This device have 4K of ROM space to store the program,and 256Bytes of RAM space, this device have ability to interface with TTL based devices and also with the external MEMORY to increase its data space, but when your are using external MEMORY the 2 ports of 89c51 microcontroller are used for this purpose.