From the abstract:

Problems bringing the Kestrel-3 up on the Nexys-2 board forces me to try bringing it up on a new FPGA board instead, the icoBoard Gamma, based around the iCE40HX8K FPGA. However, the limitations of this FPGA seriously constrains the design of the computer, as the CPU just barely fits as it is. I’ve decided to brutally murder my darlings, shed all unnecessary I/O features that basically defined the Kestrel-3 as a home computer, and focus instead on pure compute and aggregate I/O capability. Off-loading non-essential I/O to intelligent peripherals, via I/O channels, brings the design of the Kestrel-3 closer to that of an older IBM mainframe, a la System/360 or System/370.

Check out the full article here.