So, here's what I just thought of today (it's probably been thought of before) is a locked repeater RAM. I came up with a design, the good thing about it is that it's only 7 blocks in vertical height BUT width is 10x8 (when you take of the levers and buttons and extended output 4x3) Doesn't seem like it would be easy to stack either . Your probably thinking why did I even post this here, well I just thought id bring the general idea into concept ill try to make it smaller but I just brought it up as an idea. Heres some screenshots of it, sorry I don't have a screen recorder atm.