In the original, the system has a memory that is installed via individual chips.Because of its design, this chip is often called a chip DIP (dual inline package).Original IBM XT and AT had 36 sockets on the motherboard for these individual chips; rest installed on memory card that plugs into the bus slot. I've spent countless hours to populate the board with a chip like that, which really merupa a rotten job.
In addition to time-consuming and less efficient to work with memory, DIP chips had one notorious problem - the chip away from the (creeping) socket every time the system through a thermal cycle. Each had, when you turn on the power system on and off, the system gets hot and cold, and slowly chip away from the socket. In the end, no contact is good and there was a memory error. Fortunately, by placing the chip in the socket, the problem can be resolved. But the method is less intensive if you have many systems to be supported.
Alternatives to this problem is to have a memory which is soldered into the motherboard or expansion card. This prevents the chip from creeping and making connections become more permanent, but this raises other problems. If the chip to be bad, you should try to remove the old chip and install new ones, or replace the motherboard or memory card where the chip is installed. The cost for this is expensive and makes troubleshooting a memory becomes difficult.
The chip should be soldered and also must be removed, and this is what is found in the module called SIMM. For storage memory, most modern systems adopt a single inline memory module (SIMM), DIMM, or RIMM as an alternative untul: individual memory chips. This small board mounted into a special connector on the motherboard or memory card. Individual memory chips soldered on the module, making it impossible to remove or replace it. You must replace the module if any part is damaged. Modules are treated as if it is a large memory chip.
There are two main types of driver's license, two main types of DIMMs, and one type REVIM used on desktop systems. Various types are often described by the number of pins available, memory row width, or type of memory.
SIMM, for example, is available in two main types - 30-pin (8 bits plus an option for an additional parity bit) and 72-pin (32 bits plus one parity bit option for 4 additional) - with a variety of capacities and other specifications. 30-pin SIMM is smaller than the 72-pin version, and one of these versions have a chip on one or both ends.
DIMMs are available in two versions. Usually has a chip SDRAM DIMM or DDR SDRAM standard, and are distinguished by physical characteristics. Standard DIMMs have 168 pins, one notch on one side, and two notch along the contact area.DDR DIMMs have 184 pins, two notch on each side, and just one notch along the contact area. All DIMM is the width (data path) 64-bit (non-parity) or 72 bits (parity or ECC - error correcting code). The main difference between SIMMs with DIMMs are pin-pin DIMMs have different signals on each side of the module. This is called DIMM dual inline memory module, and why the only "I" extra long, DIMMs have more pins than SIMMs.
RIMM also has a different signal pins on each side. There are three different types of RIMM, namely: 16/18-bit version with 184 pins, 32/36-bit version with 232 pins, and the 64/72-bit version with 326 pins. Each version is installed into the connector the same size, but the notch in RIMM connectors and different - this is so that there is compliance. One particular board received only one type. The most common type is a 16/18-bit version that was introduced in late 2002, and 64-bit version will not be introduced until 2004.
Standard 16/18-bit RIMM has 184 pins, one notch on one side, and two centrally placed notch in the contact area. 16-bit version is used for non-ECC applications, while the 18-bit versions include additional bits are required for the ECC.
Figure 6.3 until Figure 6-7 shows the 30-pin SIMM (8-bit), 72-pin SIMM (32-bit), 168-pin DIMM SDRAM, DIMM 184-pin DDR SDRAM (64-bit), and RIMM 184 - the pin. Pins are numbered from left to right and is connected through both sides of the module on the SIMM. Pin on the DIMM is different on each side, but on the SIMM, each side is equal to the others and bring the connection. Note that all dimensions in inches and millimeters (in parentheses).
Eachtypeandcapacityof theDRAMSIMM, DIMM, andRIMM, available in variousspeed rating. Refer toyourmotherboarddocumentationfor speedandmemorytypeis right foryoursystem. It is good thatthe speed ofmemory (also called throughputorbandwidth)according to thespeed ofthe processordatabus(calledFSB-front side bus).
Ifasystemrequires aspecialrate, youcan almostalwaysreplace them withhigh-speedIebihdeterminedifspeedis notavailable. Usuallyno problemsinmixingspeedmodule, provided you usethe modulesof the same orfasterthanthe requiredIebiholelisystem. Becausethe price differenceis not much, so Ioftenbuy amodule thatIebihquickly than thoserequiredforaparticular application. This maybeuseful forfuturesystemsthatmayrequirehighspeedIebih.
SinceDIMMandRIMMhaveareport ontheonboardROM-meter speed andtimingto thesystem, thenmost systemsrunning thememory controller andmemory busat a speedcorrespondingto theDIMM/RIMMat the latestthat has beeninstalled.MostDIMMsareSDRAMmemory, whichmeanssendingdata atveryhighspeedburstwithclockedinterfaces. DDRSDRAMDIMMsas well, butDDRDIMM stransfer datetwiceperclock cycleIebihmanyof hisand thereforetwice asfaster.
Note : Bank is the smallest amount of memory to compile bans dipetiukan memory that can be invoked by the processor. Bank is the minimum amount of physical memory that is read or written by the processor at a time and is usually associated with the data bus width of the processor. If a processor has 64-bit data bus, the memory bank is also 64-bits wide. If memory interleave or running dual-channel, then the virtual bank into two absolute time data bus width of the processor.
You can not replace a module with a higher capacity unit, and then want it to function modules. Systems can have a special design limits for the maximum capacity of modules that can be accepted by the system. Modules with higher capacity work only if the motherboard is designed to receive it. See your system documentation to determine the capacity and speed appropriate to use.
Table 6:10 shows the interface connector pinout for a standard 72-pin SIMM. It also includes tables pinout detection of presence (presence detect) that show the various Presence detection pin 72-pin SIM. Presence detection pin motherboard uses to detect the size and speed of the SIMM is installed. SIMM 30-pin industry standard did not have T'tur ¬ Presence detection, but IBM adds this capability on a homemade 30-pin configuration that has been modified. Note that all the SIMMs have the same pin on both sides of the module.
Note that the 72-pin SIMM uses a set consisting of 4 or 5 pin to indicate the type of SIMMs on the motherboard. Presence detection pin is grounded or not connected, it is for it indicates the type of SIMMs on the motherboard. Presence detection output has to be linked to ground via 0-ohm resistor or jumper on the SIMM - to generate a high logic level when the pin open or low logic level when the motherboard to ground pin. From here the resulting signal can be decoded by the memory interface logic. If the motherboard to use Presence detection signal, then the POST procedure can determine the size and speed of the SIMMs are installed, and adjust the controls and addresssignalsautomatically.Thus,autodetectofsize andspeed of memorycan be made.