Low pin count
Low Pin Count (LPC) is a bus in PC systems.
In terms of software, it can be addressed like an ISA bus. This is why we speak of serialized ISA. In terms of hardware, however, it is a 4-bit bus that has no similarities to ISA; the content of the 24 ISA address lines and the 16 data lines along with various control lines is transmitted as a data packet via a 4-bit bus with LPC. The serial structure saves a lot of conductor paths compared to the parallel ISA bus.
LPC is used to connect slow and traditional hardware components to the CPU in a way that allows the use of old operating systems 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 controller, the PS / 2 - keyboard and its controller, PS / 2 mouse , the system speakers , the floppy disk Controller , simple onboard sound cards such as AC'97 , as well as classic serial and parallel interfaces .
Since all these components are already built into modern motherboards , the LPC bus is only used on the motherboard itself and, with the exception of the TPM slot, is not led out in slots .
LPC and ISA contain some control signals that the PCI and PCI Express buses lack; therefore, a standard floppy disk controller, for example, cannot in principle be implemented as a PCI plug-in card, but must be connected directly to the motherboard via LPC.
Web links
- Low Pin Count (LPC) Interface Specification. Intel, accessed March 1, 2020 .