On 31 Jan 2010 , Pete Turnbull <pete at
dunnington.plus.com> wrote:
I am really puzzled by this. The ACIA has no
hardware reset line, but
it's very easy to send it a master reset command in software. In fact,
you have to do that to clear the hardware reset condition after a power
up, because the ACIA stays in the inactive/reset condition until you
program it.
Charlie, you weren't using GTE 68C50s, were you? They did have a few
weird bugs.
I seem to remember having to send three consecutive software reset
commands to something or other, quite possibly 6850:s, and probably
Motorola ones. If you sent only one, the chip did not reset, you had to
send three at once.
/Jonas
Hi Jonas,
I sure wish you'd suggested that about 40 years ago. :)
Seriously, thanks for the tip, I'll have to try and remember that in
case I ever encounter an ACIA again.
I would have been glad to send 3 or however many commands were necessary
if would have unstuck the things. I think that when your ACIA is locked
up somehow, you're suddenly no longer in a real big hurry.
Later,
Charlie C.