Specifications

Hardware Configuration
2–47
CAUTION
Do not use resistive bus termination! If the signal requires
termination, use AC termination only.
The actual requirements for signal termination depend on system configuration, interconnecting bus
cable, and on the number and type of expansion modules used. It is the system engineer’s
responsibility to determine the need for termination.
2.17.4 Expansion Bus Connector Pinouts
Tables 2-35 through 2-38 show the pinout and signal functions on the PC/104-compatible expansion
bus connectors.
The Little Board/486i does not generate ±12VDC or -5VDC for the expansion bus. If devices on the
bus require these voltages, -12V and -5V can be supplied to the bus connector from the utility
connector (J16). +12V can be supplied through J10-1.
You do not need to add a +12V supply to program Flash EPROMs installed in the byte-wide sockets,
or for the onboard Flash device that stores the ROM BIOS, video BIOS, and optional Ethernet boot
PROM code. An onboard supply provides the programming voltage. This supply does not provide
power to the expansion bus. Most Ampro expansion products provide onboard DC-to-DC converters
to convert the +5V supply to other voltages they require.
The expansion bus pin numbers shown in the following tables correspond to the scheme normally
used on ISA expansion bus card sockets. Rather than numerical designations (1, 2, 3) they have
alpha-numeric designations (A1, A2…, B1, B2…, etc.) .