Lan Interface Boards; Thinlan Board - HP 340 Series Service Manual

LAN Interface Boards
One of two LAN interface boards may be used in the SPU:
• ThinLAN with built-in MAU, 98571-66530, ordered as Option 017 to the workstation.
It's also available as an HP 98237 A ThinLAN Upgrade to convert an SPU that has the
AUI LAN installed.
• AUI LAN, needs external MAU, 98571-66534, ordered as Option 015 to the workstation.
It's also available as an HP 98235A AUI LAN Upgrade to convert an SPU that has the
ThinLAN installed.
Local Area Network (LAN) functions are divided into three areas:
• Interface to the DIO bus.
• Shared memory area.
• Frontplane interface to the network.
Interface with the DIO bus includes select code decoding, interrupt control, data bus buffers
and latches, and address multiplexers. A 32-bit wide data bus is used.
Configuration for LAN select code and interrupt levels are fixed by hardware as follows:
• Select Code at 21.
• Interrupt level at 5.
ThinLAN Board
Figure 3-8 is a picture of the ThinLAN interface board.
Figure 3-8. ThinLAN Interface Board (98571-66530)
The shared memory area has the memory controller circuits, 16 Kbytes of RAM, 64 nybbles
of nonvolatile storage of the node address, and standard DIO control, status, and ID registers.
Multiplexing of DIO information and the LAN chip set is also part of the controller circuit.
Frontplane circuits include the LAN chip set, timer, and the transceiver chip. The LAN chip set
serves the dual function of a DMA controller and an Ethernet/EEEE 802.3 controller. Encoded
data from the SIA is transmitted by the transceiver chip. Data from the network is sent by the
transceiver chip to the SIA.
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Functional Description