Croma24 Service Manual
The direction that the Carrier Assembly is moving is known based upon the state of one detector’s output and the direction of the transition of the other detector’s output.
A hardware counter in the gate array increments as the Carrier Assembly moves left and decrements as the Carrier Assembly moves right. The hardware counter is only eight bits wide, so it cannot store a value large enough to represent an absolute Carrier Assembly position. Instead, it is read during the servo interrupt and its value compared with that from the previous interrupt. This difference is used to update the absolute position value in the software.
Interface Circuits: Serial & Parallel
Figure 2-9. Interface Circuits.
Data from the host computer is received either through the Centronics parallel port or the serial port (on the GA/CAD or GA versions only). The gate array provides the control signals for DMA transfers from the serial port to DRAM.
The serial port is designed primarily to interface to a Macintosh printer port. It has an eight pin
The serial port is compatible with
36 | Theory of Operation |
