Odd-looking scope trace on an address line

Hi folks, Clear one problem and hit another is just what I expect to happen with this Executel :) After last weekend's little breakthrough my little machine is now hitting a loop that LOOKS like it's waiting for an RST6.5 interrupt*, but at the same time the A9 line is doing this: http://www.binarydinosaurs.co.uk/STCExecutelOddTraceA9.jpg (scale doubled for ease of viewing) That doesn't look normal to me, but all 8 chips that touch A9 check out OK and there's nothing odd resistance wise. Before I start chasing my tail again I thought I'd ask first... (*for anyone interested RST6.5 is triggered by the TS1/TS2 status lines from the MR9735 teletext decoder and should be constantly active while video is being output. At one point Tony suggested this chip needs to be initialised and there is indeed a control word that can be passed to it to turn it on and off which makes me wonder if there's another memory bit stuck somewhere) Cheers! -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?