Main Board - Tektronix Phaser 340 Service Manual

5
Theory of Operation

Main board

5-16 Phaser 340 Color Printer
The main board performs two functions: it controls the actions of the print
engine and it performs the PostScript interpreting of the host's data file into a
bitmap format to be printed by the print engine. To accomplish this, the main
board features two processors and their associated support electronics.
The PostScript interpreter is based around a 29030 processor. The PostScript
software and 29030 self-tests are stored in ROM. Communication with host
computers is routed through I/O ASICs to the 29030 data bus.
The print engine controller is based on a 68330 processor. The print engine
firmware and 68330 self tests are stored in ROM. Stored engine parameters are
saved in EEPROM.
A digital motion control (DMC) ASIC controls the I
bus, which links all the printer sensors, solenoids, clutches motors, heaters and
the front panel to the main board. The I
bus interconnecting all the I/O boards. Each I/O board features an address
decoder and data buffer which respond to the DMC. The DMC writes to a
particular I/O board, for example, for that board's sensor states and then reads
that board's data buffer for the requested sensor data. Similarly, it writes to a
particular I/O board to activate its solenoids.
2
C (Inter-Integrated Circuit)
2
C bus is an independent address/data