/ /> I ought to have pointed out that most times doing what i do wastes a Yeah and when you've gone through all the steps, learned what all the chips are for, plugged them in one by one and finally the whole thing does actually work, the satisfaction is much bigger. Exactly. And I just figured that they all are framing errors. Here's my test program that should exit when it reads a byte that has no framing error: LDAA #%00010000 ; like in jbug (8bit, np, 2stop, no divide) STAA $8008 ; acia control reg READ LDAA $8008 ; acia status reg ASRA BCC READ ; branch unless data ready BITA #%00001000 ; check framing error BNE READ ; branch if framing error SWI It never exists no matter what audio file. The only thing that does work is that the data ready bit stays cleared as long as there is no audio at all. So it at least reacts to the fact that there is audio or not. Yes, it's a 6850. I measured with a volt meter, I don't have a scope (yet). RxD and RxC are high when no audio and they both drop to around 2V when audio is supplied, so I guess there's at least some signal. Also RTS is low as it should. Something weird that I don't understand is that simply adjusting the audio volume, the apparent voltage measured on the RxD changes more or less proportionally... this is supposed to be digital and FM ? Wim.