One option is to install terminals with no parity. Then if parity errors are noticed, it can be implemented later. To spot possible errors with no parity, look for any spelling errors you don't think you made. If you spot such an error, refresh the screen (retransmit from the computer). If the error goes away, then it's likely a parity error. If too many such errors happen (such as more than one every few hundred screens) then corrective action is needed such as: Enable parity and/or reduce speed, and/or use a shorter/better cable. Enabling parity will not reduce the number of errors but it will tell you when an error has happened.
Just the opposite policy is to initially enable parity. Then if no parity errors (error symbols on the CRT) are ever seen (over a reasonable period of time, say a month or two) it may be safely disabled.
Bits/Character
This is the character size (the number of data bits per character excluding any parity bit). To use international character sets you need 8 bits. But it's not of much use unless your terminal has the fonts for them. See Character-Sets If you are only going to use ASCII characters, then select 7-bits since it's faster to transmit 7 bits than 8. Some very old terminals only support 7-bit characters.
Which Flow Control (Handshaking) ?
The choice is between "hardware" (for example dtr/cts) or "software" (Xon/Xoff) flow control. While hardware flow control may be faster (if the one or two extra wires for it are available in the cable and if the terminal supports it) in most cases Xon/Xoff should work OK. Some people report that they solved disturbing problems (see below) by converting to hardware flow control but software flow control has worked fine at other installations (and for me personally).
If you use software (Xon/Xoff) flow control and have users who don't know about it, then they may accidentally send an Xoff to the host and lock up their terminal. While it's locked, they may type frantically in a vain attempt to unlock it. Then when Xon is finally sent to restore communication, all that was typed in haste gets executed, perhaps with unexpected results. They can't do this with hardware flow control. See Flow Control for an explanation of flow control.
Port select
Since most terminals have two or more connectors on the back, it is usually possible to assign one of these connecters to connect to the host computer and assign another connector to be the printer port. The connector may have a name next to it (inspect it) and this name (such as Aux, Serial 2, or Modem) may be assigned to either be the main host connection or the printer connection (or the like).
