On 2012-10-09, at 20:02, Gerrit Heitsch wrote: > I can look into it, but it will take some time since I don't have the time during the week and this weekend is also already full. Also, I know I have most parts, I'm not sure about the sockets. You don't have to.. I got my analyser (and a scope too), connected couple of suspected lines and noticed strange "noise" popping in at some points. Like sometimes _OE/_CS was following the _KERNAL properly and sometimes not. Also, sometimes it was dropping down by itself for a very narrow (in the sense: short) period. So I connected scope to the line and saw that those periods on the analogue looked very un-digital, leading back to the very same suspicion about power lines noises. To make it all short: the error was in the PCB. When adding (not really needed) ground plane I removed one connection but didn't add thermals to the ground plane on pin 12/14 arrghh... This meant effectively that only EPROM had proper GND and the rest... well.. not. After connecting ground plane to reference GND - yeah - works as it should! Now time to think about 27C512 with place for more KERNALS. Since I want at least three (CBM, Dolphin, Jiffy) 512 with some sort of encoder switch will have to do until Michau builds our ultimate ROM replacement board.. -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-10-16 21:00:09
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