One ram cuse ithip, one eeprom, a big asic with the rest of the logic, a pair of head drivers and a full bridge to drive a stepper, a half bridge for the paper feed, a driver for a solenoid and a few other bits and you have it all. 3 wires to the psu are 0V, 41v and power control, the 3v3 regulator is normally on the mainboard via a small SO8 switcher on the back of the board. The power control drops the main rails to about 10v during standby to reduce power consumption.