Type of Memory Packages

 Type of Memory Packages :-

   Memory package is a small circuit board that contains memory chips. SIMM,DIMM,SODIMM, AND RIMM are some of the memory packages. These packages are the form factors of RAM chip. The installation of a memory depends on the form factors of a RAM. A form factor is the size and shape of the memory packages.

Single In-line Memory Module ( SIMM) :-
                  SIMM is a small circuit board desingned to hold memory chips. It contains pins for accepting data from the control circuit. These circuit boards or modules are known as apckages. There are various SIMM packages available based on the number of pins it contains. For Example there are 30 pin packages and 72 pin packages.
The capacities of a 30-pin package SIMM package are 256 Kb, 1 MB, 2 MB, 4MB,8MB,16MB RAM. It contains 2,4,0r 8 chips per module. A 30-pin SIMM package has a data bus width of 9 bits with 9- bit parity . Parity checks the accuracy of the data transmission. An odd parity and an even parity are the two modes of parity checking.
A 72-pin SIMM package has 32-bit data width with 36-bit parity . PS/2 is another term used for the 72-pin package . The capacities of a 72- pin package are 1 MB, 2MB, 4MB,8MB,16MB,32MB,64,MB,AND 128MB RAM. It contains 2,4,8,or 16 data chips permodule. FPM DRAM uses a 72-pin package.

Dual In-line Memory Module (DIMM) :-
         DIMM package is also a small circuit board that contains the memory chips. The difference between the SIMM and DIMM is that DIMM is a 168-pin package. The data of the DIMM packages are 64-bit ,72-bit, or 80-bit. A 168-pin DIMM package is available in thr SDRAM, EDO or FPM DRAM chips.

Small outline Dual In-Line Memory Module (SODIMM) :-
              Laptops and notebook systems uses this package. It is the smallest version of the DIMM. The SODIMM package has a notch at the bottom of the circuit board. This notch helps in inserting the SODIMM package is the memory socket. SODIMM packages are available with 144 and 200 pins. A 144- pin SODIMM package has 64-bit data path. The FPM DRAM and EDO RAM use this package. The 72 pins on both the sides of the package divide a 144-pin package.
A 200-pin SODIMM package has 64-bit data path. PC2 100 memory and pc2700 memory use this package. The 100 pins on both sides of the package divide a 200-pin package .

Micro DIMM :-
            Micro DIMM stands for MIcro Dual Inline Meory Module. This package is smaller than DIMM and SODIMM packages. The sub-notebook systems use these memory packages. The Micro DIMM package pins connect the memory module with the memory socket. These pins provide two communication lines for the module and the system. This Package does not have the notch at the bottom. Micro DIMM packages are vailable with 144 and 172 pins.

Rambus Inline Memory Module (RIMM) :-
         RDRAM chip uses the RIMM memory package . This package is same as the DIMM package. It only differs in the pin configuration. The high bandwidth and the low latency application use this memory package .
The RIMM package has a data storage speed of 600 MHz, 711 MHz, 800 MHz and 1066 MHz. It has 184 connecting pins. The distance between each pn in the RIMM package is 1mm. This package starts opearting from 2.5 voltage supply. The RIMM package are available in 16-bit data buses 32-bit data buses, and 64-bit data buses. The memory bandwidth of the RIMm package is up to 9.6 GB per second.

Working of RAM

WORKING OF RAM :-

        RAM stores the data until the processor is executing the current data. Once the processor finishes the current execution, RAM forwards the next data to the processor.
The processor accesses the Data from the RAM is a random order with the help of the memory cell address. The cell address contains the row number and the column number of the memory cell. When the processor receives the data, it actually receives the memory cell address of the data. The RAM controller accepts the memory cell address. The RAM controller reads the data from the cell address and then sends the data in its respective address lines. The address lines contain the transistors and the capacitors for reading the data. The control circuit reads the capacitor when the transistors opens the cell. When the capacitor is charged , the memory cell returns a bit value as 1. When the capacitor is empty, the memory cell returns the bit value as 0.
In DRAM, each cell contains a pair of transistors and capacitor. Each cell represents a single bit of data in the binary format of 0 and 1. The capacitor stores the data in the memory cell. The transistor with the help of the memory control circuit reads these memory cells.A transistor acts as a switch. It turns on when the control circuit reads the capacitor. It turns off when the capacitor is empty. The DRAM Controller refreshes the capacitor after each reading of the memory cell. DRAM refreshes automatically. access speed of RAM is 80ns to 50 NS.

Type Of RAM

   Type Of RAM :-
    
RAM is the main memory of the computer. It holds the data until the system is turned off.once the system is switched off the data is lost. There are two types of Ram , Static RAM and Dynamic RAM.

Static Random Access Memory(SRAM) :-

1) Stores data till the power is supplied
2) Uses an array of transistors for each memory cell.
3) Does not need refreshing the memory cell after each reading of the transistors.
4) Data access is faster
5) Consumes more power
6) It is Expensive.

Dynamic Random Access Memory (DRAM) :-

1) Stores data only for few milliseconds even when power is supplied.
2) Uses a single transistor and capacitor for each memory cell
3) Needs refreshing the memory cell after each reading of the capacitor
4) Data access is slower
5) Consumes less power
6) Less Expensive

Memory

  Memory is one of the functions of the brain that enables to store and remember the past events. Similarly, in Computers the term memory refers to a chip that stores data. It also enables us to retrieve the stored Data. The processor retrieves information stored in the memory for processing Data. The storage capacity of a memory depends on the type of the memory package used.

Types of Memory

Memory can be divided into two types, Volatile memory and non volatile memory. Volatile memory temporarily stores the data. It loses data as soon as the system supply is turned off. Non-volatile memory stores data permanently.It does not lose the data even if the system supply id turned off.
Further, Memory is classified into physical memory, logical memory, virtual memory and flash memory.

Two types of Physical Memory :-

RAM - Stands for Random Access Memory. It is a semiconductor-based memory where the CPU or the other hardware devices can read and write data. It temporarily stores the data and it is a volatile memory.Once the system turns off, it loses the data. As a result, Ram is used as a temporary storage area.
                         Types Of RAM :-

ROM - Stands for Read only Memory. It stores the Data permanently and it is a non volatile memory. It does not lose data even after the system turns off. As a result ROM is a permanent data storage area.

Logical Memory:-
                                 Logical memory enables the user to use large amount of memory to store data.It defines a way to organize the physical memory such as RAM and cache. This enables the operating system to arrange memory into a logical manner such as assigning a logical address. Logical address is a memory location and it is accessed by an application program. The system maps the logical address to real physical storage address.

Virtual Memory :-
                                 Virtual memory is a part of the hard disk which is used as a memory . It has a set of memory addresses and stores the instruction or the data. When the processor executes the instructions it converts the virtual memory addressed into real memory addresses. The main use of the virtual memory is to increase the address space.

Flash Memory :-
                            Flash memory is the high-density device. It is a non volatile memory. It is fast in reading and writing data. This is because it writes data in chunks or blocks. Flash memory is an electrically re-programmable device. The contents from the flash memory are erased in blocks and not in bytes. The block size can range from 256 bytes to 16 kB . Flash Memory can replace hard disk in portable computers. In this context, flash memory is available as pc card that you can plug into the PC MCIA slot.

Cache Memory :-
                                Cache memory is a small and fast memory which is placed between the CPU and RAM.It is accessed at a very high speed than the system memory. As a result, the programs which access the same data or instructions over and over run faster. The cpu does not have to transverse to the main memory to get the data . It will first access the cache to find the data.