Thanks to Curt's great archiving work, we have the designer's notes on The Graduate peripheral for the 2600:
They invented a 3-cycle "Bus Stuff" mode, to achieve an even faster TIA register update rate than the Harmony's 5-cycle/DPC+ "Fast Fetch" mode.
This works by loading Y with $FF at the beginning of the kernel, and then having the 6507 execute 3-cycle STY $REG instructions. At the critical moment when the
Thanks for the demo!
I tried it on real hardware. I tested it on a few different consoles and it doesn't seem to work consistently. (Sorry for the very low quality of the pictures, but they should be enough to show the problems) On a Light Sixer, the second 8 pixel wide column of graphics is shifted 1 pixel to the left. This glitch is present on all the 4 screens. On a 7800, in addition to that, there are a series of vertical lines (again, this happens in all the screens of the demo).