Mistification from slingshot, many many many thanks!
Changed mist to use simulated sd card, rather than the custom protocol
Split PAL pll into two - now much closer to real frequency
Improved timings for PAL and NTSC
Added ZPU. Added read/write SD support. Fixed joystick. Switched to new mist keyboard mode (ps2 emulation).
Re-connected SDRAM to DE1
Connected up SDRAM. Make 800XL core wait for SDRAM reset to complete. Also had to adjust phase offset to make it work - need to get a proper setup for mist
Wired up mist with internal ram/rom. Tested OK.
Current unmerged vhdl for my Atari800 core and start at merging them into one tree with a common core