Specifications

Hardware Configuration
2–42
2.14 BATTERY-BACKED CLOCK
An AT-compatible battery-backed real-time clock (with CMOS RAM) is standard on the
Little Board/486i. The clock is powered by a 3.6 volt Lithium battery soldered to the board. Battery
drain for the clock is less than 1 uA. This battery will support the clock for about 10 years. (This
assumes that the battery is not also used to supply backup power to SRAM devices in the byte-wide
sockets.)
The factory initializes the real-time clock and various parameters in the configuration memory for a
standard configuration. The factory sets the date and time, but it may not be set for your time zone.
Use the Ampro SETUP utility to change these values as needed.
The contents of the configuration memory are also stored in an onboard EEPROM. The ROM BIOS
reads the EEPROM to get configuration information if the CMOS RAM data is lost. This means that
the board will function without the battery. Note that without a battery, the real-time clock date and
time will not be correct.
2.15 WATCHDOG TIMER
A unique feature of the on-board clock circuitry is a watchdog timer. You can program this timer to
generate an interrupt or reset signal if the programmed time interval expires before the timer is
reinitialized. Use SETUP to select the time interval. The options are: Disable, 30 seconds,
60 seconds, and 90 seconds.
The watchdog timer uses the standard alarm feature of the real-time clock. In a standard AT, the
alarm output is connected to IRQ8. On the Little Board/486i you can also jumper the alarm output to
I/O Channel Check (-IOCHCK) or Reset with W11. I/O Channel Check is the bus signal that triggers
a non-maskable interrupt (NMI). Reset is a hard reset signal, the same as pressing the Reset button.
For the watchdog timer to generate I/O Channel Check, short W11-1/2. For Reset, short W11-2/3. To
disable the watchdog timer, leave W11 open, and select Watchdog Timer Disable in SETUP.
If you enable the watchdog timer in SETUP, but do not install a jumper on W11, IRQ8 will turn off
the interrupt and the system will continue, unaffected. If you select I/O Channel Check, the watchdog
timer will generate a message on the screen. If you select Reset, no interrupt handler is required.
Figure 2-15 Watchdog Timer Response Jumper (W11)
2.16 UTILITY CONNECTOR (J16)
Seven functions appear on the 16-pin connector at J16. These are:
! Auxiliary power connections
! Power indicator LED
! PC speaker
! Push-button reset switch