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I have made a number of hardware and software modifications to a 6809 version of Grant Searle's FPGA-based multicomp design. Those modifications are described here in the hope that they may be of use or interest. All of the associated files are either referenced or are part of the repository here.

• Why Bother
• Operating system
• Caveat Emptor
• Stuck?
• Projects

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Hardware

• Hardware Overview
• Multicomp Construction
• Simulating multicomp
• Debugging
• Altara hints and kinks
• Modifications to Grant's design: VDU modifications, SD Controller modifications, CPU and clocking modifications
• Additions to Grant's design: GPIO unit including Adding a RTC
• Additions to Grant's design: simple memory mapping unit (obsolete) and mk2 memory mapping unit - the latter also includes a Timer and a SingleStep unit.

You can also find detailed construction details for a Multicomp PCB, and pre-built FPGA and SDcard images here.

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Emulation

• exec09

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Software

• Programming guide
• CamelForth including CamelForthSaveLoad
• Lennart Benschop's 6809 debug monitor, BUGGY
• CUBIX
• FLEX including Booting a pre-built FLEX system disk, porting FLEX from first principles, Overview of .dsk files, creating an SDcard for FLEX, manipulating FLEX .dsk files, extracting disk images from an SDcard, run FLEX on exec09, a tour of the FLEX system disk, recompiling Colossal Cave, FLEX internals and FLEX hints and kinks
• Fuzix
• NITROS9 including links, Booting a pre-built NITROS9 system disk, porting NITROS9 L1, porting NITROS9 L2, NITROS9 hints and kinks, mc09 L1 Boot files, mc09 L2 Boot files