Motorola MVME5100 manual Switches and Indicators, ABT/RST Switch, Abort Function, Reset Function

Operation

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Introduction

This chapter provides operating instructions for the MVME5100 Single Board Computer. It includes necessary information about powering up the system along with the functionality of the switches, status indicators, and I/O ports on the front panels of the board.

Switches and Indicators

The front panel of the MVME5100 as shown in Figure 1-1, incorporates one dual function toggle switch (ABT/RST) and two Light-Emitting Diode (LED) status indicators (BFL, CPU) located on the front panel.

ABT/RST Switch

The ABT/RST switch operates in the following manner: if pressed for less than 5 seconds, the ABORT function is selected, if pressed for more than 5 seconds, the RESET function is selected. Each function is described below.

Abort Function

When toggled to ABT, the switch generates an interrupt signal to the processor. The interrupt is normally used to abort program execution and return control to the debugger firmware located in the processor and flash memory.

The interrupt signal reaches the processor via ISA bus interrupt line IRQ8. The interrupter connected to the ABORT switch is an edge-sensitive circuit, filtered to remove switch bounce.

Reset Function

When toggled to RST, the switch resets all onboard devices. To generate a reset, the switch must be depressed for more than five seconds.

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