Accelerometer Schematic

Below is a rough schematic of the layout of the accelerometer PC board looking from the component side. The microcontroller is an Atmel AT89S8252, an 8051 clone. This microcontroller is in-circuit programmable using an SPI interface. The SPI pins are also used to drive the MMC. To permit the dual use there is a jumper block (located below the 74AHC244, marked "P" and "R") that allows the pins to be connected for programming (P) or running the code (R).
Source:http://www.randomuseless.info/accelerometer/schematic/schematic.html