The TG68 does not have a regular 68000 interface, nor does it implement a real 68000 bus cycle. This features an Intel Cyclone IV FPGA as well as 32MB of SDRAM and a few other peripherals that aren’t of much interest here. The FPGA board itself is a Terasic DE0 Nano, for no particular reason other than I had a spare one. A proper PCB with an FPGA integrated will be designed in due course. This has proved to work perfectly well for testing, although the grounding did need to be beefed up with copper tape to get things working reliably. Rather than going straight to a custom PCB I made the decision to use an existing FPGA development board that I had on hand, along with a simple level shifting interface put together on stripboard.
This core is already proven in projects such as Minimig and MISTer, so it seemed like a logical choice. These are getting increasingly hard to find for a reasonable price.įor the last few weeks I’ve been tinkering with hooking an FPGA up to an A500+ in place of its 68000 CPU with a view to using the open-source TG68 core as a fast 68020.
Most of these are based on the long obsolete faster derivatives of the 68000, such as the 6800. The Amiga is still a popular platform with enthusiasts, with the vibrant add-on scene still seeing new accelerator cards being developed.