Genicom 3600 Front Panel Interface, Debug Interface, Chip Select Generation, Option Connector

Appendix A

Chip Select Generation

GALs U23 and U25 are designed to take the MC68332 bus control signals and convert them into ASIC and I/O option control signals. A state machine governs the timing of the signals and also dictates that the /OPTION_ASICCS from the processor be programmed for two wait states.

I/O Option Connector

The I/O option connector J8 is a 40-position pin field. Two chip selects, /OPTION∗ and /BOKI/O∗, are used to select either the board identification number or the data port. XMT and RCV are outputs from the I/O option cards that are inverted and go to the processor to generate communications interrupts.

FIFO

The FIFOs U11 and U24 are the same part as used in the Intermec 3400 and 4400 printers. The IDT 72105 is a 256 x 16 FIFO with parallel inputs and serial output. The processor loads image data into the FIFO with word writes. At the beginning of a line, the MC68332 loads three lines of data into the FIFO. This causes the HF flag to go high. The ASIC then begins clocking data out of the FIFO. The processor checks each line of the HF flag and loads the next line of data if there is still more image to load. If the image has been completely loaded, the FIFO empties and the /EF flag goes low. The low /EF flag tells the ASIC to stop clocking data from the FIFO.

Front Panel Interface

Connector J15 connects to the front panel board. Inputs consist of one button (Feed/Pause) and three LEDs (Power, Alert, and Empty/Pause). The Alert LED indicates system errors or printhead over-temperature. The Empty/Pause LED indicates a paused state or a media fault.

Debug Interface

J5 provides a debug interface to the processor, which allows for troubleshooting of the main PCB. This interface can be used to put the processor into background mode and then send commands to read or write memory or register locations. This interface is used for in-house functional testing and is used for engineering development.

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