Question about modems

[Nigel Johnson]

I actually have an original Hayes 300 modem. Would it be any use if I 
could set it up for a a test, or would it need another genuine Hayes one 
to talk to for what you need?

cheers,

Nigel


On 13/11/2019 02:25, Jim Brain via cctalk wrote:
> I am the author of tcpser, a UNIX/Windows program that emulates a 
> Hayes modem.
>
> Some time ago, Chris Osborn (FozzTexx) forked a copy of my project to 
> fix some bugs and he also added in some parity code, which looks to 
> strip parity from the incoming serial connection (in the case that the 
> serial port is set as 8N1 and the computer attached to it sends in 7E1 
> or similar.
>
> I am working to merge in all of his changes into the mainline 
> codebase, but I am unclear on prpper Hayes behavior.  His Readme says:
>
> https://github.com/FozzTexx/tcpser/commit/5f0e28bb837463e597a1daf9b3c07e56af887b7d 
>
>
> "I also made the modem routines automatically detect parity and ignore
> it in AT commands and print out modem responses in matching
> parity. Parity is *not* stripped when sending data over the
> connection, which is how a real modem behaves. This may or may not be
> what you want. Some servers will expect an 8 bit connection and may
>
> not work."
>
> Did Hayes modem really do that?  I thought most later modems self 
> detected parity and speed and thus would have switched both the comm 
> on the serial port and the data sent to the other side in the same 
> parity (if the terminal was 7E1, the modem would configure as 7E1 and 
> send 7 bit data to the other side.
>
> But, maybe real modems did as Chris notes. Anyone have guidance on 
> this?  The goal of tcpser is to emulate a Hayes modem as much as 
> possible, but I never really thought about mismatched parity on the 
> RS232 line and how to deal with it.
>
> Jim
>
>
  

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