Specifications
Computer Architecture and Maintenance (G-Scheme-2014)
Pentium and Pentium Pro processor sockets.
Zero Insertion Force
When the Socket 1 specification was created, manufacturers realized that if users
were going to upgrade processors, they had to make the process easier. The socket
manufacturers found that 100 lbs. of insertion force is required to install a chip in a
standard 169-pin screw Socket 1 motherboard. With this much force involved, you
easily could damage either the chip or the socket during removal or reinstallation.
Because of this, some motherboard manufacturers began using low insertion force (LIF)
sockets, which required only 60 lbs. of insertion force for a 169-pin chip. With the LIF or
standard socket, I usually advise removing the motherboard—that way you can
support the board from behind when you insert the chip. Pressing down on the
motherboard with 60–100 lbs. of force can crack the board if it is not supported
properly. A special tool is also required to remove a chip from one of these sockets. As
you can imagine, even the low insertion force was relative, and a better solution was
needed if the average person was ever going to replace his CPU.
Manufacturers began using ZIF sockets in Socket 1 designs, and all processor
sockets from Socket 2 and higher have been of the ZIF design. ZIF is required for all the
higher-density sockets because the insertion force would simply be too great otherwise.
ZIF sockets almost eliminate the risk involved in installing or removing a processor
because no insertion force is necessary to install the chip and no tool is needed to
extract one. Most ZIF sockets are handle-actuated: You lift the handle, drop the chip
into the socket, and then close the handle. This design makes installing or removing a
processor an easy task.
Socket 1
The original OverDrive socket, now officially called Socket 1, is a 169-pin PGA
socket. Motherboards that have this socket can support any of the 486SX, DX, and DX2
processors and the DX2/OverDrive versions. This type of socket is found on most 486
systems that originally were designed for OverDrive upgrades. Figure shows the
pinout of Socket 1.
Prepared By – Prof. Manoj.kavedia (9860174297 – 9324258878 ) (www.kavediasir.yolasite.com)
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