Technical data

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Functional Description
4
Ethernet Interface
The MVME172LX uses the Intel 82596CA LAN coprocessor to
implement the Ethernet transceiver interface. The 82596CA accesses local
RAM using DMA operations to perform its normal functions. Because the
82596CA has small internal buffers and the VMEbus has an undefined
latency period, buffer overrun may occur if the DMA is programmed to
access the VMEbus. Therefore, the 82596CA should not be programmed
to access the VMEbus.
Every MVME172LX that has an Ethernet interface is assigned an Ethernet
Station Address. The address is $08003E2xxxxx where xxxxx is the unique
5-nibble number assigned to the board (i.e., every MVME172LX has a
different value for xxxxx).
Each board has an Ethernet Station Address displayed on a label attached
to the VMEbus P2 connector. In addition, the six bytes including the
Ethernet address are stored in the configuration area of the BBRAM. That
is, 08003E2xxxxx is stored in the BBRAM. The upper four bytes
(08003E2x) are read at $FFFC1F2C; the lower two bytes (xxxx) are read at
$FFFC1F30. The MVME172 debugger has the capability to retrieve or set
the Ethernet address.
If the data in the BBRAM is lost, use the number on the label on backplane
connector P2 to restore it.
The Ethernet transceiver interface is located on the MVME172LX main
board, and the industry standard connector is located on its front panel
Support functions for the 82596CA are provided by the MC2chip. Refer to
the 82596CA user’s guide and to the MC2chip description in the
MVME172 VME Embedded Controller Programmer’s Reference Guide
for detailed programming information.
SCSI Interface
The MVME172LX supports mass storage subsystems through the
industry-standard SCSI bus. These subsystems may include hard and
floppy disk drives, streaming tape drives, and other mass storage devices.
The SCSI interface is implemented using the NCR 53C710 SCSI I/O
controller.