[Will] wrote a 128MHz Z80-based retro microcomputer which runs on a Papilio Pro board. For those who don’t know, the latter is built around a Spartan-6 LX9 FPGA so you may imagine that much work was required to implement all the computer features in VHDL. The T80 CPU core was taken from opencores, the SDRAM controller was imported from Mike Field’s work but [Will] implemented several additional functions on his own:
– a 4KB paged Memory Management Unit to translate the 16-bit (64KB) logical address space into a 26-bit (64MB) physical address space.
– a 16KB direct mapped cache to hide the SDRAM latency, using the FPGA internal block RAM
– a UART interface for external communications
He also ported CP/M-2.2, MP/M-II and UZI (a UNIX system) to the computer. His project is completely open-source and all the source code can be downloaded at the end of [Will]’s write up.
Thanks [hamster] for the tip.