low pin count (LPC)

The LPC bus(Low Pin Count) was developed by Intel and is used on the motherboard of personalcomputers and single- board computers. In terms of concept, the LPC bus corresponds to a serially operating ISA bus, whereby the number of bus lines is significantly lower, which is also expressed in its name.

In contrast to the ISA bus, the LPC bus has a maximum of seven lines, whereas the ISA bus has 30 or 72 lines. Furthermore, as a serial bus, the LPC bus only requires four signals for control and transmission: Frame, Clock, Reset and Data. Other commands are for interrupt, direct access to RAM and other functions. Since the data is only transferred via one bus line, the data rate of 33 MHz is correspondingly higher than with the parallel ISA bus.

The LPC bus is mainly used for connecting PC components with low bandwidth to the central processing unit( CPU), for example for the boot ROM, for audio controllers and older input/output units. For software, the LPC bus behaves in the same way as the ISA bus.