7 Nov
2011
7 Nov
'11
3:48 p.m.
On Mon, Nov 7, 2011 at 3:32 PM, <cctech at vax-11.org> wrote:
One particular TTL <--> RS232 chip (I forget the PN) had the really annoying
problem of blowing up if it was connected to a powered-up terminal while the
chip was powered down. This may be the cause of your dead UART. Beyond that
I don't have any suggestions.
Clint
It's not clear to me what is used for the RS-232 interface on the
CQD-220. I don't see any obvioius RS-232 interface chips. There are
a handful of diodes and resistors adjacent to the RS-232 port. Maybe
those make up the RS-232 interface. There is no UART on the board. I
have never been curious enough to try to trace the signals to try to
determine how the serial interface is implemented.
-Glen