Slot CPU

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Slot CPU with socket 775 (PICMG 1.0)
PICMG - backplane for slot CPU

A slot CPU is a special, very compact design of a PC motherboard in the form of a PCI or PCI / ISA-like plug-in card.

Application and properties

Slot CPUs are widespread in the industrial sector and, thanks to their compact dimensions, allow both use in very tight spaces and extremely flexible expansion options with optimal use of space thanks to the modular principle. The expansion can take place both with the help of customized additional boards, which are simply plugged piggyback onto the slot CPU, as well as so-called backplanes , which are plugged into the slot CPU at a 90 ° angle and PCI and / or ISA slots in several height levels above or below the slot CPU. A package consisting of a slot CPU, a backplane and expansion cards can achieve a higher packing density than a comparable system with a conventional ATX motherboard.

construction

Due to the limited space, the actual slot CPU usually only contains the most elementary functional units of a PC , usually only processor , chipset , graphics and a memory bank for SDRAM as well as IDE , floppy , mouse and keyboard controllers , and for industrial requirements to meet - a 10 / 100TBase - LAN controller. The fixed sockets are even more sparse on the outside, all of which have to be accommodated in a single plug-in card slot bracket. Numerous sockets of elementary interfaces can therefore optionally be routed to the outside via connecting cables.

Depending on their area of ​​application, slot CPUs are usually equipped with Socket 370 ( Pentium III , VIA C3 ) and Socket 479 ( Pentium M ) - the corresponding processors have become firmly established in the industrial sector. But cards for the Pentium 4 are also available.

Slot CPUs reverse the construction principle of a conventional PC: While in a conventional PC the main board is the main level, which with the PCI or other slots allows a fixed number of 90 ° rotated secondary levels, the slot CPU has both the main board and the main board Expansion cards on parallel, stacked and roughly the same size levels. The height expansion or the number of possible expansion cards can be varied very easily with different backplanes. The central connecting element is the backplane.

distribution

Slot CPUs are not represented in the consumer sector or in the mass market, because more emphasis is placed here on the cost-effective production of extensively equipped complete systems that are installed in tower housings that are practically always the same shape . Flexible use of space thanks to the modular principle would therefore not bring any advantage here. Use in particularly compact HTPCs would be interesting . However, this is countered by the lack of support from particularly inexpensive consumer processors such as the Celeron D or models from AMD .

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