21 Apr
2015
21 Apr
'15
5:10 a.m.
On 04/20/2015 07:50 AM, tony duell wrote:
Thanks Tony, looks like it's straight MDA, then - 1 and 2 are grounded, and
3,4,5 are n/c.
I'm still surprised that there was a market for new Hercules boards in
1990, although I suppose it's possible that it was part of a batch made for
a specific contract. That 4" of bare PCB is just weird, too, perhaps
suggesting that it was made for a specific application where having the
card secured at both ends was useful.
cheers
Jules
display? Given the date I just want to check that it's not one of their CGA
or EGA compatibles.
You don't need to trace much to figure out what it is (assuming it's standard
[1]).
First check if pins 1 and 2 of the DE9 are solidly grounded. If pin 1 isn't, it's
something
strange. If pin 2 isn't (but pin 1 is), it's likely to be EGA [2]. If they are
both grounded, then
it's likely to be MDA (hercules) or CGA.
Now check if pins 3,4,5 are connected or floating. The diode check range on a DMM is
useful here, try it both ways round between the pins and ground. If all are floating,
it's MDA,
if they are all driven, it's CGA.