l?rdag 24 mars 2018 skrev Douglas Taylor via cctalk <cctalk at classiccmp.org>: I guess I wrote that a couple of years ago. If I remember correctly the way I did research into this was to attach a 40 pin DIP clip connected to my logic snalyzer on on the various MICROM chips and there were no activity at all when the board got out of RESET. Then I removed one chip at a time to see if there were any difference. This particular chip made a difference. After removing it there were busactivity. I have not yet got around trying with -3.9V Bias chips to see if that make the board run better. If your board is the later E etch then it has 3.9V bias and you could directly use chips from a KD11-HA board. /Mattis