83C795 Datasheet, PDF (70/136 Pages) List of Unclassifed Manufacturers – Ethernet System Controller

HOST INTERFACE SECTION
83C795
S torage of Us er-Defined Initial Configurations
To define any of the 15 recallable configurations ,
follow thes e s teps.
1. Build an image of the desired configuration
registers in the LAN register bank (SWH=0,
addr=8:F).
2. Write the unlock/store sequence with the fi-
nal EA field of the EEROM register selecting
the desired configuration bank. Do not use
Bank 6 because that is reserved for the per-
manent device LAN address. Do not use
Bank 10 either because that is reserved for
driver-related information storage and can-
not be recalled as a board configuration.
3. Wait about 200 msec or poll the STORE bit
to determine whether that operation has
completed.
S torage of Us er-Defined LAN Addres s
To s tore a us er-defined LAN addres s, follow these
s teps.
1. Program the desired LAN address, board ID
register, and checksum register with desired
values.
2. Write the unlock store sequence with the final
EA field of EEROM register selecting the
Bank 6.
3. Wait about 200 msec or poll the STORE bit
to determine that operation has completed.
S torage of Us er-Defined Data
In some applications , there may be other data you
need to save in the E E R OM, like board type and
revis ion numbers , multicas t filter acceptancemas k,
s oftware driver parameters , and the host machine
type. S ince s ome E E R OM locations may not be
needed for configuration or LAN addres s s torage,
they can be us ed for this purpos e.
1. Overwrite LAN address, board ID, and
checksum registers with the data you need
to save.
2. Store the data as if it were a board configu-
ration. The driver setup program uses this
method to store driver related parameters
into EEROM Bank 10.
To recall this us er defined data, program the E A
field for the bank and do a R ecall operation.
6.8 PLUG AND PLAY
T he 83C795 s upports the Plug and Play IS A
S pecification. T his s pecification provides full and
interactive configuration of all PnP -compliant
boards ins talledon theIS Abus . T heess ential s teps
in this proces s are the abilities to:
• Power up and reset Plug and Play devices
• Send out an initiation key to bring all PnP de-
vices into a known state
• Isolate each ISA adapter in turn
• Read the adapter’s resource requirements
• Arbitrate the available resources to all of the
PnP cards
• Identify each board and configure its resources
• Activate the cards on the ISA bus
• Locate a suitable driver for the adapter, if nec-
essary
Tobeeffectivein this newenvironment, the83C795
contains the logic neces sary to prepare any board
on which it is placed for Plug and Play s tandards .
T his logicwill be active only when both the PNPE N
bit (E R FAL.0 as read from E E R OM) is s et and a
3.6kΩ resistor is connectedtotheMA[6] pin (JMP6)
between MA6 and GND.
T his s ection contains a brief overview of how Plug
and Play works , along with information s pecific to
the 83C795’s implementation of PnP. F or more
detail on the Plug and Play process and protocol,
please refer to the latest vers ion of the Plug and
Play IS A S pecification.
6.8.1 Auto-Configuration Ports
T he Plug and Play protocol requires that all logic
not related to PnP on a PnP board not res pond to
any IS Abus acces s until thePnP logicactivates the
card, except for devices required for boot (s ee
S ection 6.8.5). Until this happens , the only access
to the card is through the PnP auto-configurations
ports . T hes e ports cons is t of three 8-bit I/O
regis ters, as shown in Table 6-6.
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