VersaLogic VL-EPM-31, Hardware Reference Manual, Page: 56 / 77

Expansion Interfaces
EPM-31 Hardware Reference Manual
55
PC/104-Plus Expansion Bus
The EPM-31 provides a legacy stack-down PCI connector at locations J11 (for PCI) and J10 (for
ISA) on the bottom side of the board for PC/104-
Plus (PCI +ISA) as well as PCI-104 (PCI only)
and PC/104 (ISA only) expansion modules. Figure 3 on shows the locations of these connectors.

Integrator’s Notes:

PC/104 ISA only modules (those that have no PCI connector) must not be positioned
below the PC/104-Plus (PCI+ISA) modules in the stack.

Modules with PCI interfaces must be above those with only ISA interfaces.

PCI-104 PCI only modules (those with no ISA connector) must not be positioned below
the PC/104-Plus (PCI+ISA) modules in the stack.

In general, PC/104 (ISA only) and PCI-104 (PCI only) cards can never be used together in
a stack.
Table 17 lists the maximum PC/104- Plus slot current rating on the EPM-31. This is the aggregate
power available to both the PCI and ISA connectors. ISA does not use +3.3 V power, so all of the
+3.3 V power is available for the PCI connector.
Table 17: PCI/104-Plus Connector (PCI) Maximum Current
Voltage Maximum Current
+5 V 4.0 A
+3.3 V 3.0 A
+12 V 1.0 A
–12 V 0.5 A
ISA B
US
(
ON
PC/104-P
LUS AND
PC/104 E
XPANSION
M
ODULES
)
Refer to the ISA sections of the
PC/104-Plus Specification
for a complete description of this
interface.
The EPM-31 implements the ISA bus on PC/104- Plus and PC/104 expansion modules using an
LPC-to-ISA bridge implemented in the FPGA. This LPC-to-ISA bridge supports all features
except the following:

The ISA bus must not be mastered by an external module. The EPM-31 is always the bus
master. The MASTER signal on pin D17 of J10 is not connected.

The REFRESH output signal on B19 of J10 is not supported; it is pulled up to a high logic
level.

DMA is not supported. The seven DACKx outputs on pins B15, B17, B26, D8, D10, D12,
and D14 on J10 are pulled up to a high logic level. The seven DRQx inputs on pins B6, B16,
B18, D9, D11, D13, and D15 on J10 are not connected. The Terminal Count (TC) output on
pin B27 of J10 is pulled low.

–5.0V power is not provided on J10 pin B5. This pin is not connected.