DL11 M7800

tony duell ard at p850ug1.demon.co.uk
Thu Jun 16 09:17:59 CDT 2016

> This further helps my understanding.  Problem is, the card is bad.  Knowing
> it's probably jumpered correctly (assuming I have everything right, which
> is a big assumption) I will check the 1488/89 drivers, etc. to see what's
> wrong with the card.

What I would do is : 

Check that there are transmit and receive clocks at the UART pins
(pin 40 and pin 17 IIRC). If missing, check the clock circuitry, crystal,

Check that there is a character strobe (I think the UART pin is 
called 'TRL' -- Transmit Register Load) at the UART when you
try to write to the appropriate address. Make sure you don't
get a bus timeout error when you do that too. If that's 
not right, check the address decoder, bus slave logic, etc

Check if there is any data coming out the UART on the Transmit
register output pin. If not (and if everything else is OK), suspect
the UART chip. But check it's not being held reset, it's getting 
power, etc.

Check the transmit driver (1488)

Check the cable, if it's not the one you used with the other 
serial port card.


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