Memory Devices
One of the material learned in the course elektronikaI rani is a memory device. Until now actually rani still puzzled, why this material into electronic courses (short for casual electronics hehee .. ^ ^). Emang connect, yes ... Hmm ... On second thought ... Hmm ... well smartphone from the 'same one digital component. Hmm ... yowis of the curious straight into the material aja, yes ... Yuks ....

Memory Chip
Memory chips consist of a number of memory cells into which the bits of data can be stored or written. Data stored can be searched or read back (retrieve) of these devices. These memory cells are grouped to form a memory location (memory location one bit, two bits, four bits, or eight bits). Data stored in these locations is called the word (word). A word is composed of several bits and is the basic unit of information in the system. Words (numbers), which consists of four bits called a nibble, while the word consisting of eight bits called bytes. Each location has a unique binary code, called the address (addresses) that are used for identification.

Time Access
Apart from counting the location and width of each location, a memory chip has other properties that must be taken into account if it will be used in digital systems, this is called the access time. Access time is the time required (speed) to a memory location in memory chip for these locations is available for the data bus. Access time is the same as the time interval between an address sent to memory chips and the time interval when the data stored in these locations appears on the data bus. Chip memory access time varies from between 200 to 450 ns.

Not volatile and volatile memory
There are two types of memory: volatile and not volatile. Volatile memory will lose data stored therein when power supply is removed. In the non-volatile memory, the data will remain stored in the memory does not depend on whether the power supply to memory chips. Of the two categories above, there are some memory packages.

ROM
ROM (Read Only Memory) is not volatile memory used to store data permanently. The data stored can only be read by users, so no names and new data can be written into the ROM into the device. ROM is programmed by the factory according to user specifications. After the data entered, data can not be changed anymore.

PROM
The fact that the ROM is programmed by the manufacturer means the price can be very expensive unless it is produced in very large quantities. Furthermore, the conversion program that previously had been written into the ROM is very expensive. To avoid this, use of memory chip that can be programmed. PROM (programmable read only memory) can function as well as the ROM but the PROM can be programmed by the user or manufacturer. The plant will provide a blank PROM with all bits are 1 or 0. Users will be programmed keeping with the "blow" single-way switches at certain places in order to menngubah flow of logic in such venues. PROM once programmed can not be programmed again.

EPROM
The main disadvantage of PROM was unable to re-programed. Thus, errors in the program can not be corrected. EPROM (erasable programmable read only memory) address the issues. Users can delete data that has been saved and changed the program. Programs that have been stored can be erased by illuminating the memory cells with ultra-violet rays through the "window" that existed on the PC. This process will take approximately 20-30 minutes. After this process the IC will be empty again, and ready to re-programed. EPROM has two losses:
a.Keseluruhan contents must be removed before re-programed. This means the elimination of some of the contents of memory are not possible.
b.IC should be taken from the circuit when will be illuminated. This means the elimination of the program can not dilakuakn place.

EEPROM
EEPROM (electrical erasable programmable read only memory), which is also often called EAPROM (electrical alterable programmable read-only memory) to overcome the problems that arise in the EPROM. The contents of EEPROM can be erased and reprogrammed in place by using an appropriate electrical signal. Furthermore, certain locations of the EEPROM can be erased and reprogrammed without disturbing others.
RAM
RAM (random access memory) is volatile memory chip where the user can read data and write data into it, so the memory is also often called a memory read / write. Lokai-memory locations can be accessed at random by placing the address of the selected location into the address line.