Specifications

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2.4 PERIPHERAL CONNECTIONS AND CONFIGURATION
This section covers the interface requirements of the board's external device interface connectors.
Information is provided on interface and device characteristics, connector pinouts, signal
definitions, jumper configuration, and nonvolatile Configuration Memory setup.
2.4.1 Utility Connector
A single 12 pin connector (J4) provides five functions: Speaker, Reset, Power Indicator LED,
auxiliary power to the AT Expansion Bus connector (J9), and a Power Good status signal. The
pinout and signal definitions of the Utility Connector are shown in Table 2-9. Note that the
power connections indicated are not required for operation of the Little Board/286, and are only
used to provide power for cards connected to the board's AT Expansion Bus connector.
Table 2-9. Utility Connector (J4)
PIN SIGNAL NAME
FUNCTION
1 Speaker + 5 volts through 33 ohms
2 Speaker - audio signal
3 Ground To one side of Reset button
4 Reset To other side of Reset button
5 LED Cathode Ground return
6 LED Anode Current source (+5V through 330 ohms)
7 Ground Ground return
8 +12V power To J9 pin B9
9 -5V power To J9 pin B5
10 -12V power To J9 pin B7
11 Ground Ground return
12 POWER GOOD Power supply status
Speaker
The board provides an AT compatible speaker output on two pins (1,2) of the Utility Connector.
The speaker signal is buffered by a transistor amplifier to provide approximately .1 watt of audio
power to an external speaker. Typically, a small general purpose 2 or 3 inch diameter permanent
magnet speaker with an 8 ohm voice coil is used.
Speaker tones can be generated either by directly bit-banging the speaker control port or by setting
Timer 2 to a desired frequency tone and enabling the tone with an enable port. Refer to an AT
technical reference manual for custom programming information.
Pushbutton Reset
Two pins (3,4) of the Utility Connector provide connections for an external normally-open
momentary switch to manually assert a system reset signal. Pin 4 is the reset (active low) input,
and pin 3 is the logic ground.