universal stepper motor controller

after doing some datasheet reading and experiments with ATiny13 uC universal stepper motor controller has finally grown up enough to show it! :) final version uses AT89C2051 uC, uses interrupts and enters idle mode often, in order to minimize power consumption. it supports both unipolar and bipolar stepper motors, has step-by-step mode along with continuous (aka: “turbo”) mode of operations.