The CD4012 is a CMOS technology based, 4-input NAND gate Dual package, i.e. the IC has two NAND gates which can operate independently and each gate can take in four Inputs. It is commonly used in buffer circuits, logic inverter circuits etc.
The CD4008 is a high speed, high voltage 4-bit full Adder IC with carry out feature. The IC has four independent stages of full adder circuits in a single package. It is commonly used in applications where arithmetic operations are involved.
The AT24C256 is a 32K byte, 8-pin EEPROM IC. As we know EEPROM stands for Electrically Erasable Programmable Read-Only Memory, we can store information on this IC and it will remain there even when the power is turned off just like your pen drive.
DAC0808 is a D/A converter IC and is used for converting 8 bit digital data input to analog signal output. It is a monolithic IC featuring a full scale output current settling time of 150 ns while dissipating only 33 mW with ±5V supplies.