Question about modems

Electronics Plus sales at
Wed Nov 13 18:25:18 CST 2019


The case presented is an true corner case.  Usually modems can be set
for rate, bits, and parity that matches the target system.  AS modem
became more sophisticated (26/33/56k) they were easily set and I just a
few I have.  Older 300/1200/2400 baud modems like DEC DF02/03 had
switch settings likely others did too.  The 9600 were generally smart.

Those that used AT command set were very setable as there was usually
large menu of options.

There were exceptions "winmodems" that were only hardware port
and the system did all the work in software.  Generally flaky
to the max.  DEC DFxx series had their own non AT command set.

What is forgotten is that many of the modem programs could swich
parameters on the fly after carrier detect went true.

Like RS232/432 signaling the art and science is getting lost
to time and age.  I'd bet more than half here never used a
modem or have not in more than 15-20 years.


And here my problem is that I have the old modems, but I can't test them because I no longer have a land line. Is there any way to test an internal or external modem without anything except broadband or cellular connections? I know I can't test the acoustic modems, but I was hoping to be able to test internal ISA and PCI, as well as external modems from 300 baud to 56k. Perhaps there is some inexpensive gizmo available?


More information about the cctech mailing list