IBM 6400-I15 Maintenance Manual - Page 45

CMX Controller Board The heart of the printer is the CMX controller board, which monitors and directs all printer functions. The controller board receives and processes all data from the host computer, builds the printable images, controls all motors, and drives the hammer springs. Except for the power supply and final hammer drive circuits, all logic and drive circuitry for the printer are contained on the controller board. The CMX controller board consists of two functional units: the Data Controller (DC) and the Engine Controller (EC). The DC is responsible for: ♦ Host I/O ♦ Operator I/O ♦ Security Interface ♦ Print Image Generation ♦ Overall High Level (Logical) Control The EC is responsible for: ♦ Print Mechanism Operation ♦ Print Mechanism Fault Monitoring ♦ Power Shutdown/Power Saving Modes The EC and DC communicate through semaphore registers. The DC receives host and operator input and returns dot images and LCD messages to buffers in memory. Image data are passed to the EC upon request, are processed, then sent to the hammer bank. The EC synchronizes paper, ribbon, platen, and shuttle motion as it feeds dot data to the hammer drivers. Figure 17 summarizes this architecture. Principles of Operation 45