The .ENET Driver
the AppleTalk connection file for EtherTalk when the user has selected
EtherTalk from the Network control panel. You can write your own protocol
how to send data to it directly for transmission over the Ethernet network, and
how to write a protocol handler to receive data from the network.
The system .ENET driver locates and opens the drivers for installed NuBus
the open resource files for a driver with a resource type of 'enet' and a
resource ID equal to the board ID of the NuBus card. If it doesn't find such a
driver resource, it then looks for a driver named .ENET in the slot resources
in the ROM of the NuBus card. See Designing Cards and Drivers for the
Macintosh Family, second edition, for discussions of NuBus board IDs and slot
resources.
Providing Your Own Ethernet Driver
If you write an Ethernet driver for use with your own Ethernet NuBus card,
you should provide the features and functions described here. You can store the
driver in the firmware of the NuBus card as described in detail in Designing Cards and Drivers for the Macintosh Family, second edition, and in
NuBus card, you must name the driver .ENET. If you provide a RAM-based
driver, you must give it a resource type of 'enet' and a resource ID equal to the
board ID of your NuBus card. The 'enet' resource type is identical to the 'DRVR'
Note: You must not name a RAM-based driver .ENET, because doing so
would replace the system .ENET driver.
If you write an Ethernet driver for use with a non-NuBus network interface
(such as an Ethernet card for the Macintosh SE/30 or an Ethernet connection
through the SCSI port), you should provide the features and functions
your driver.
Changing the Ethernet Hardware Address
Each Ethernet NuBus card or other Ethernet hardware interface device
contains a unique 6-byte hardware address assigned by the manufacturer of
whether to receive a packet. To change the hardware address for your node,
place in the System file a resource of type 'eadr' with a resource ID equal to the
slot number of the Ethernet NuBus card. If the Ethernet device is not a NuBus
card (it might be a slot card in a Macintosh SE/30, for example), use a
resource ID of 0.
Do not use the broadcast address or a multicast address for this number. (The
broadcast address is 0x0FF-FF-FF-FF-FF-FF. A multicast address is any
Ethernet address in which the low-order bit of the high-order byte is set to
finds one, the driver substitutes the number in this resource for the Ethernet
hardware address and uses it until the driver is closed or reset.
Note: To avoid address collisions, you should never arbitrarily change the
Ethernet hardware address. This feature should be used only by a system
administrator who can keep track of all the Ethernet addresses in the
system.
Opening the .ENET Driver
determine which NuBus slots contain EtherTalk cards. The OpenSlot function described in Slot Manager to determine which NuBus slots contain EtherTalk cards. To find EtherTalk NuBus cards, use the value catNetwork in the field
spCategory of the SGetTypeSRsrc function parameter block, and use the value typeEtherNet in the field spCType. If you cannot find any EtherTalk
NuBus cards, you should also attempt to open the .ENET0 driver in case a
non-NuBus EtherTalk card is attached to the system. You should provide a user
interface that allows the user to select a specific EtherTalk card in the case
that more than one is present.
The following code example illustrates the use of the SGetTypeSRsrc // Finding an EtherTalk card and opening the .ENET driver
// Assume inclusion of
#include <AppleTalk.h>
#include
#include <Slots.h>
#include
void DisplaySInfo(SpBlock *mySBlk); void DoError (OSErr myErr); short found;
Str15 enetStr;
Str15 enet0Str;
short myRefNum;
found = 0; // assume no sResource found
strcpy ((char *) enetStr, (char *) "\pENET");
strcpy ((char *) enet0Str, (char *) "\p.ENET0");
mySBlk.spParamData = 1; // include search of disabled resources.
// Start searching from spSlot and search
// the slots above it as well.
mySBlk.spCategory = catNetwork;
mySBlk.spCType = typeEtherNet;
mySBlk.spDrvrSW = 0;
mySBlk.spDrvrHW = 0;
mySBlk.spTBMask = 3; // match only Category and CType fields mySBlk.spSlot = 0; // start search from here
mySBlk.spID = 0; // start search from here
mySBlk.spExtDev = 0; // ID of the external device
do {
if (! myErr) {
// You found an sResource match; save it for later.
found++;
SaveSInfo(&mySBlk);
}
} while ( myErr != smNoMoresRsrcs);
if ( found > 1 )
{
// if you found more than one sResource, put up a dialog box
// and let the user choose one. if any of the sResources you
// found were disabled, let the user know they are not available.
DisplaySInfo(&mySBlk);
}
if (found)
{
myPBRec.slotDevParam.ioCompletion = nil;
myPBRec.slotDevParam.ioNamePtr = enetStr;
myPBRec.slotDevParam.ioMix = nil; // reserved
myPBRec.slotDevParam.ioFlags = 0; // single device sResource
myPBRec.slotDevParam.ioSlot = mySBlk.spSlot;
myPBRec.slotDevParam.ioID = mySBlk.spID;
}
else
if ( myErr)
DoError( myErr);