Altair serial port update

[Tony Duell]

> 
> All:
> 
> 	Word to the wise -- always check the cabling. I've been wracking
> my brain this week on the serial port problems with my Altair. I wired
> the serial board cable per the manual but I never checked if it was NULL
> or not. Well, when I put a null adapter on the cable, it worked! Whoo,
> hoo.

I don't want to say how many times I've made that sort of mistake :-)

Another word to the wise... Get one of those little in-line RS232 
testers. The one I have has 7 bi-colour LEDs on it that monitor TxD, RxD, 
RTS, CTS, DSR, DTR and CD. I've seen one with more LEDs too.

I'm always using mine to cheack whether an RS232 port is wired as a DTE 
or DCE. Or if it drives any of the handshake lines. I find it a lot more 
use than my fancier breakout boxes, comms analysers, etc.

-tony