Com 226 comp trouble shooting II theory book
Memory Package Styles and Structures
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| Memory Package Styles and Structures Ultimately, the memory die is mounted in a package just like any other IC. The completed memory packages can then be soldered to your motherboard or attached to plugin structures, such as SIMMs, DIMMs, and memory cards. Only four package styles are normally used for memory devices - DIP (Dual Inline Package) This classic IC package is used for through-hole mounting (prior to surface-mount technology. The advantage of DIP ICs is their compatibility with IC sockets, which allows ICs to be inserted or removed as required. Unfortunately, the long metal pins can bend and break if the IC is inserted or removed incorrectly. Also, the overall size of the package demands extra space. DIP ICs were used in older PCs (286 and earlier systems) and older VGA/SVGA video boards. DIPs are still sometimes used on motherboards to provide cache RAM. - SIP (Single Inline Package) This type of IC package is rarely used today—there are simply not enough pins. However, they did make a short appearance with memory devices in late-model 286 and early 386 systems, which flirted with proprietary memory expansions. I remember NEC using such devices in a MB add-on for their 386SX/20— and you needed to add that module before you added even more memory in the form of proprietary SIMMs. SIPs can be troublesome because they are difficult to find replacements for, so expect replacement memory modules using them to cost a premium. - SOJ (Small-Outline J Lead) This is the contemporary package style for surface mount circuits. The leads protrude from the package like a DIP, but are bent around just under the package in the form of a j. Sockets for SOJ packages are often used for replaceable memory ICs, such as the BIOS ROM, but most RAM devices are soldered directly to the motherboard as system memory (or a video board as video RAM. SIMMs often use SOJ memory components. - TSOP (Thin, Small-Outline Package) Like the SOJ, a TSOP is also a surface-mount package style. However, its small, thin body makes TSOP memory ideal for narrow spaces. Expect to find such devices serving as memory in notebook/sub-notebook systems or PCMCIA cards (aka, PC Cards. Download 1.89 Mb. Share with your friends:
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