Specifications

Theory of Operation
4 4
4-7
Ethernet Controller
The EPC-8 contains an on-board Ethernet controller connected through the 16-bit
EXM expansion interface, which is compatible with Western Digital 8013, Novell
NE2000 and NE2000+ cards through the use of National Semiconductor's DP83905
(AT/LANTIC chip). The default configuration for the Ethernet port is as a WD8013-
compatible card. The I/O base address is 240. Interrupts are signaled on IRQ5.
These parameters can be changed by running the AUTOSET.EXE program that is
optionally available from your supplier. The possible alternative interrupts are IRQ3,
IRQ9 and IRQ15.
The EPC-8 Ethernet port has two 8 Kbytes x 8 RAM chips for packet buffering and a
10 Base-T interface. Eight-bit network drivers cannot be used with the EPC-8.
For more information about the AUTOSET.EXE program, refer to Appendix H.
Resident Flash/SRAM Memory
The EPC-8 can optionally be built with 2 Mbytes of Flash memory and 128 Kbytes of
Static RAM resident on the processor board.
Resident Flash Memory
The resident Flash memory is accessed via 8-bit read/write registers and physically
appears on the EXM expansion interface as if it is in slot 31. It is enabled as if it were
a standard RadiSys EXM expansion card in that slot.
The EPC returns an ID of FD to a read of address 100. This is the same ID that would
be returned from a RadiSys EXM-2A card. You can use the optional
XFORMAT.EXE utility to format and load the resident Flash memory under MS
DOS. The EXM-2A and the resident Flash memory cannot both be used in a single
EPC-8 system. Note: You must set jumper JP5 (“ FLASH” ) before the Flash can be
written. Jumper locations are described in Figure 2-1.
SRAM
The battery-backed SRAM is memory mapped. The resident SRAM resides on the
EXM expansion interface and, when populated, can be accessed at 0xFX3XXXXX or
0xFXBXXXXX. If there is less than 16 Mbytes of DRAM, it may also be accessed
at 0x00BXXXXX. A battery low indicator (low when 0) is returned in bit 0 of
register 8387.
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