A few years ago I worked on, with Hias' help, some breakout boards for the DE1 adding Atari XL compatible ports. To this end I built two prototype boards with different sets of ports. Eagle files of these are available.
I had been intending to enter these into the ABBUC hardware contest this year but missed the deadline because I got ... distracted. I decided to build a mainboard which I could use instead of the DE1. Thiis led to the creation of several prototype mainboards, which eventually led to the creation of the EclaireXL.
Adds the core Atari controller and IO ports to the DE1 or Eclaire XL. Some work is still needed on SIO clock in/clock out (I don't have anything that uses them)
More core work is needed to support PBI devies, though it is fairly well understood what needs doing. PBI signals: A0-A15,D0-D7,RST_N,IRQ_N,REF_N,MPD_N,EXTSEL_N,RW_N,PHI2
There are many FPGA boards providing controller input, video out and audio out. However pretty much none of them break out IO for adding the rest of the system IO ports. Here I try to break out as much as possible (108 pins) while still supporting the A2 up to the A9. The A2 is enough for the Atari XL and should allow running the core 64K and hardware regs at 57MHz (not yet implemented - 28MHz tested on DE1).
The eclaireXL board has been designed to accomodate an F23 484 pin FBGA Cyclone V E. This includes a number of compatible devices. The board uses a common subset of the pins that should allow all these to work: Note that the regulators for 1.1,2.5 and 3.3V supply up to 500mA, so please check usage. For the A8 core its using about 100mA so plenty spare...
The picture shown is of the prototype board, some fixes/improvements have been done to the eagles files since - but not yet produced.