🚀 go-pugleaf

In article <815522417snz@digits.demon.co.uk>
           John@digits.demon.co.uk "John" writes:

>I bought Demons 16550 UART I/O card but, rather short sightedly, I
>got the single port version :-(

Now that's what I call skinflint, #507 !


>The card is a "SEG model SC5500 high speed serial card"
>
>Nine months further on I now want to upgrade it to a dual version.
>It has a 40 pin socket free (presumably for a second 16550 chip!)

Indeed.


>It also has two 14 pin sockets free (hopefully, for a couple of
>standard CMOS chips).

CMOS ?  Don't know the technology but they are standard RS-242 buffer
drivers and there are already some others of the required types on the
card, type numbers ending ...48 and ...49 as I recall.

You can tell which ones go where as the Tx chip has two power rails, +12
and -12 while the Rx chip os just +5. Simple inspection of the PCB should
give the game away especially as the pinouts of the chips are in the Maplin
and RS catalogues.

-- 
John Beardmore