atmel 89c52 interfacing..help!!

hi, im trying make an intruder alarm using atmel 89c52.since im a complete novice in using microcontroller i donno how to interface the various components required. i need to interface a keypad(4 or more buttons),LCD ,a buzzer and 2 sensors.how do i do that?

i need someone to tel me which sensor can be used if it is to detect opening of a door or window and how to interface it with mic? does it need any other circuitry other than sensor and mic?
One more thing... im using C language or programming mic and using keil. i have written some code but donno how to get started with keil...please help??

any sensor with digital output and same voltage level can be connected to a MCU while analog input can be connected to ADC inputs. MCU outputs can drive (sink and source) 20mA resistive loads or use BJTor MOSFET to drive higher current.
i think assembly is easier, a simple LD instruction from port or to port can read or write data.

I think optical Range Sensor is also nice and cheap such as GP2D12. see
http://www.junun.org/markiii/Info.jsp?item=9
for more details.

thank u for writing,but i was actually hoping to get basics about some sensor or keypad architecture which will help me to write a program for interfacing,just like we have architecture description of mcu,'s. hardware interfacing is not that difficult.if u have anything like that plz share..

89c52

Go to www.Atmel.com and you'll find so much information
you'll be reading for days. They have software you might be
interested in and design and code examples. If you need some
components go to https://groups.yahoo.com/group/YoungScientistsClub
and I have stuff there that might be helpful.