The T030 has now been equipped with an ENC28J60-based ethernet module along with an SD card adapter. At first I created a simple SPI bitbang driver that used a couple of the GPIO pins on the 68901 MFP. It worked fine, but naturally it was pretty slow. My first intention was to make a SPI master with yet another CPLD chip, but then I discovered the TP3465 Microwire Interface Device, which is essentially a complete SPI master with an 8 bit parallel interface to the host processor. This has been added on a separate daughterboard as I ran out of space on the prototype DRAM board. The TP3465 communicates perfectly with both the SD card and the ethernet module.
I now consider the hardware part completed for what I am trying to accomplish with this project.
The ROM BIOS for the T030 is also progressing. I have created a rudimentary TFTP client on top of a the simple TCP/IP stack from tuxgraphics.org, which I have modified to run on the T030. I have also integrated the FatFs library, so it is now possible to download binary images from a local TFTP server, and store and load them from the SD card.