Specifications

2 - 13
Power Indicator LED
Two pins (5,6) of the Utility Connector provide connections for an external power indicator LED
device. 15 mA of sourced current is available (+5V through 330 ohms). Pin 5 goes to the LED's
cathode, and 6 to its anode.
AT Bus Power Options
Four pins (7,8,9,10) of the Utility Connector allow the connection of an external source of
+12VDC, -5VDC, and -12VDC power to the board's AT bus (J9) for use by plug-in expansion
cards. The Little Board/286 does not require these voltages.
Power Good Signal
Two pins (11,12) of the Utility Connector provide connections for a power good signal from
power supplies which offer this feature. The purpose of this signal is hold the system in a reset
state when power is not within the proper range. This signal connects to the board's reset
circuitry, and is functionally equivalent to the Pushbutton Reset (pin 4). This input has a TTL
level, Schmitt trigger conditioned input buffer, and requires an active low input of 1 second
minimum duration for the system to reset reliably.
2.4.2 Keyboard
An AT compatible keyboard can be connected to the board's keyboard port via the first five pins
(1-5) of connector J5. Normally, AT keyboards include a cable which terminates in a male 5-pin
DIN plug for connection to an AT. Table 2-10 gives the board's keyboard connector pinout and
signal definitions, and includes corresponding pin numbers of a normal AT DIN keyboard
connector.
Pin 6 of J5 can be connected to a keyboard inhibit switch. When this pin is grounded, keyboard
inputs will be ignored. This can be used with key operated switches for system security.
Four additional locations (7,8,9,10) of J5 are not ordinarily populated with connector pins. Of
these, pins 7 and 8 are not connected, while pins 9 and 10 duplicate the function provided by
W22, the video mode jumper (discussed earlier). If required, you can include the video mode
jumper function in a cable assembly for external access.
Note
“PC” keyboards are not compatible with “AT” keyboards,
and may not be used with this interface