The ZX spectrum core is great and it looks correct, but on some games the sound/music is not accurate. The developper's website
http://www.mike-stirling.com/r…a/zx-spectrum-on-an-fpga/ says "Cycle accuracy – there is no memory contention and the CPU core doesn’t match the timing of the real Z80."
Do you know how it could be improved? Is someone working on this?