Homebrew 68K Machine Has A PCI Bus

The Peripheral Component Interconnect (PCI) bus was first introduced all the way back in 1992. It quickly became the standard way to interface add-on cards on the PC platform, supplanting earlier buses like ISA and various other oddball standards. You wouldn’t expect to see a PCI bus on a Motorola-based machine, but [maniek86]’s homebrew rig offers just that. 

This computer is a beautiful piece of homebrew engineering, constructed out of protoboard and loose wires rather than any fancy PCB. At the heart of the build lies a Motorola 68000 running at 10 MHz. It’s got 1 MB of SRAM, 4 KB of ROM, and a MC68681P acting as a UART, timer source, and I/O controller. Where things get special, though, is in the inclusion of a Xilinx Spartan II FPGA (XC2S100), which acts as a PCI bridge. It provides the machine with two 32-bit 5-volt PCI slots which are interrupt capable, albeit with no bus mastering. A XC95144XL CPLD also sits present to act as glue logic to help lace everything together.

[maniek86] does a great job of explaining exactly why the PCI bus was hard to implement, and how it was pulled off in the end. The guide also covers how the system was able to interface various cards, from a PCI serial expansion to a Cirrus VGA adapter. It’s all good stuff.

We’ve featured other work from [maniek86] before, too, like this brilliant 486-based single-board computer. Video after the break.