Service manual

Service Manual
Summary
The Ethernet II expansion card hardware design tries to
be as transparent, in terms of data transfer, as possible.
Where design requirements have allowed, flexibility has
been given to the way the software can use this
hardware platform, at the same time trying to maintain
minimum
system overhead. Much of the flexibility of the design is
achieved by the use of the DP8390 (NIC), which is a
complicated device containing several internal registers
allowing software to dictate operation. Therefore access
to the Ethernet/Cheapernet LAN is achieved by software
drivers that firstly prime the device by direct access and
then leave the expansion card to run free, requiring only
burst data transfers across the podule interface, an
interrupt being used when intervention is required.
Bibliography
The following publications will be of interest to
technicians and users wanting to find out more about
Ethernet and the Acorn Ethernet II card:
• ANSI/IEEE Std 802.3 – 1985 ISO draft International
Standard 8802/3 ISBN 0-471-82749-5, Carrier Sense
Multiple Access with Collision Detection (CSMA/CD)
access method and physical layer specifications.
• National Semiconductor data sheet for the DP8390C
NIC. In the National Semiconductor Data
Communications, Local Area Networks and UARTs
Advanced Peripherals Handbook, available from
National Semiconductor (UK) Ltd, 301 Harpur Centre,
Home Lane, Bedford MK40 1TR.
• 'A-series Podules', specification issue 2.0, available as
an application note from Acorn Computers Limited (
address at the front of this manual).
Fig 2-12: Ethernet/Cheapernet links
Part 2 - Interface cards Issue 2, June 1991 2-17