One day my partern says lets make this old board smaller. But a lot of IC6821. So emulate them into an FPGA. So i developed the code in VHDL. The 6821 is a peripheral from MOTOROLA. It has two bidir ports PA,PB and four interrupt inputs, two of them also can be configured for handshake.
-- On 16 december 2005 i finished the coding and some basing simulation using the QUARTUS web edition.