The stepper motor is controlled by two outputs on port B of UC2 (STP0, and STP1). A binary four count is developed from these two lines, driving the four phases of the stepper motor. The PLA converts STP0 and STP1 into four outputs that represent one of the four states in the count (Y0,Y1,Y2,Y3). The Spindle motor is controlled by the output MTR of UC2. The PLA inverts this signal. It is then passed to the motor speed control pcb.
UC2 pin 14 is an input that monitors the state of the write protect sensor, and pin 13 is an output that controls the activity light (RED LED). UC7 decodes the addresses output from the processor when selecting UC2. UC2 resides at memory locations $1800-$180F.
|This page has been created by Sami Rautiainen.|
|Read the small print.||Last updated September 05, 2020.|