eharmon

The Apple Ethernet NB is a fascinating device, utilizing the Macintosh Coprocessor Platform (MCP) and it’s A/ROSE operating system and 68000 processor to add ethernet functionality to NuBus Macintosh. Despite being released in 1991, this powerful combination theoretically allows for significant offloading of packet handling from the main processor, freeing it up for other processing tasks.

But does it? The answer is…muddy.

Card Revisions

For one, there’s three major revisions of ethernet cards for NuBus:

  1. EtherTalk NB, a 12" card with BNC and AUI connectors, utilizing a National Semiconductor DP8390 ethernet controller.
  2. Ethernet NB, a 9" card with AAUI connector, utilizing the MCP chipset and a National Semiconductor Sonic DP83932 ethernet controller.
  3. Ethernet NB Twisted Pair, a 9" card with an RJ45 connector, utilizing a National Semiconductor Sonic DP83934 ethernet controller.

Only the second card has the required MCP chipset with 68000 co-processor required for running A/ROSE. As a result, the others use more standard Sonic drivers.

Driver Revisions

From inspection we can see “vanilla” NB used A/ROSE from it’s first release through at least driver version 1.0.4. But examining the changelog for 1.1, released with the Network Software Installer 1.4.2, we find:

Ethernet driver version 1.1 for the Apple Ethernet NB Card

========================================
Ethernet driver version 1.1 now allows the SONIC to transmit packets by building chains “on the fly”.  This results in a faster Ethernet driver.
This card no longer uses A/ROSE, but runs in “slave” mode.  It now uses the same Ethernet driver that the Ethernet NB Twisted-Pair card uses.
Better allocation of memory when Virtual Memory is on.

Emphasis mine. In other words, starting with driver 1.1 A/ROSE is bypassed entirely. You can confirm this by removing the A/ROSE and EtherTalk Prep extensions from the system and you’ll find the card continues to work properly with 1.1 and higher.

Apple continued to update the driver at least through Mac OS 8.0 which shipped with version 1.2.3.