Question about modems

Nigel Johnson nw.johnson at
Wed Nov 13 12:41:08 CST 2019

On 13/11/2019 13:36, Chuck Guzis via cctalk wrote:
> There are other "oddball" combinations, such as 8E1 and 8O1, which sends
> a 9-bit data frame.  You can see datasheets on some UARTs as well as MCU
> UARTs that support the 9 bit packet.
According to the diagram of the Smartmodem there is no UART, the 1488s 
and 1489s go directly to the Z80.
> Also, don't/doesn't TDD (5 level code) use 5E2 or some such.  Same for
> Telex/TWX.

Not sure 5 level code (ITU #2) ever had parity, but to confuse the issue 
even further, there was a 1.5 stop bit option too, for mechanical machines!



> --Chuck


Nigel Johnson

Amateur Radio, the origin of the open-source concept!

You can reach me by voice on Skype:  TILBURY2591

If time travel ever will be possible, it already is. Ask me again yesterday

This e-mail is not and cannot, by its nature, be confidential. En route from me to you, it will pass across the public Internet, easily readable by any number of system administrators along the way.
    Nigel Johnson <nw.johnson at>

Please consider the environment when deciding if you really need to print this message

More information about the cctech mailing list