Question about modems
nw.johnson at ieee.org
Wed Nov 13 05:31:05 CST 2019
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?
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:
> "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.
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