Low Pin Count

Low Pin Count (LPC ) is a bus in PC systems. This can be addressed by software such as an ISA bus. Therefore, is also spoken by a serialized ISA. In terms of hardware, however, it is a serial bus that has no similarities to the ISA; the contents of the 24 ISA address lines and 16 data lines together with ISA ISA signals of various control lines are transmitted as commands via one and the same serial data line at LPC. Through the serial setup many conductive paths can be saved, thus reducing the production cost of the board compared to the ISA bus in parallel.

LPC is used to combine slow and old-fashioned hardware components in a way to the CPU, which allows the use of old operating systems and application programs from the ISA era ( such as MS- DOS) and supports the boot phase of newer operating systems. These components are essentially the BIOS ROM, the real time clock, the classical interval timer and interrupt and DMA controllers that 2 keyboard and its controller, the 2 mouse, the system speaker, the floppy disk drive controller simple onboard sound cards such as AC97, as well as classic Serial and parallel interfaces.

Since all of these components have already been incorporated in modern motherboards, the LPC bus is only used on the motherboard itself, and not led out in slots.

LPC and ISA contain some control signals that are missing the PCI and PCI Express bus; therefore, a standard floppy disk drive controller, for example, in principle, not be run as PCI card, but must be directly connected to the motherboard via LPC.

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