I've followed Tony's advice and went step by step, one board no chips,
chips loaded, second board no chips, measuring at each step. Finally
all seemed fine, I fired it up and now I've got RAM from 0000 all the
way to 7FFF :)
I ought to have pointed out that most times doing what i do wastes a
little time, and in fact it owuld heen fine just to plug the board in and
power up. But this is amply compensted for by the time saved when thigns
go very wrong.
Next essential thing is the Load routine (from audio) that doesn't seem
to work. I wrote a routine to read bytes from the ACIA just like the
JBUG load routine does and simply quits when the first byte is read. It
Wht is the value of that byte? Is it the same every time you play the
same audio file into the mahcine? Does it change with different audio files?
loops until I start to play the audio file, so it
actually detects that.
However when I make it loop until it finds a non zero data byte, it
Do I conclude from this that the first byte read --- in fact all bytes
read -- are always 0?
It's been a long time since I looked at the 6850. What does this chip do
if the RxD pin is stuck low? Does it keep on claiming to have received
bytes of value 0, albeit with framing errors?
never stops. So I thought all the analog stuff is
working up to the ACIA
I assume this ACIA is a 6850. What does the data input do when you play
the audio file? Where does the Rx Clock signal come from, and is it correct?
-tony