28 May
2009
28 May
'09
5:16 p.m.
Fred wrote:
We saw him dial, and put the handset into the cradle,
but he did NOT
shut the lid. The notch is there for a reason. If you don't close
the lid, ambient noise, such as a nearby printer or 026, can be a
problem.
Chuck wrote:
Yeah Fred, but a modern laptop isn't nearly as
noisy as an ASR33! I
don't recall Silent 700 terminals having any such lid on the acoustic
coupler.
Many ASR33s were equipped with an acoustic coupler to the right of the
keyboard and printer, and they didn't have any cover to exclude outside
noise. They worked fine even though the ASR33 itself was quite noisy,
because 103 FSK modulation at 110 baud [*] had a lot of noise margin.
Eric
[*] These were actually 110 baud, since there was a one-to-one mapping
of bits to modulation symbols. Later modems were often incorrectly
described as 1200 baud, 2400 baud, 9600 baud, etc., when in fact the
quoted number was their data transfer rate in bits per second, and the
baud rate was a fraction of that.