11 Dec
2004
11 Dec
'04
5:07 p.m.
Fred Cisin <cisin(a)xenosoft.com> wrote:
the ASR33 TTY is Bell 103 at 300 baud?
That's what I've always thought, anyone who knows otherwise please correct
me.
"MODERN" modems that will do Bell 103, will
often only do it at 300 baud.
Yes, that's what I wrote in my previous post. My question about 300 baud
Teletypes went unanswered though.
I do, however, have a few TI Silent 700s. These are absolutely lovely
300 baud portable terminals, small and portable enough to compete with
modern laptops, and even though they weren't made by Teletype, I think
of them as portable teletypes. There were two versions: 703 with RS-232
interface and 707 with a built-in Bell 103 modem. My only 703 doesn't
work (the printhead moves but prints nothing), but my 707s work great,
and I do in fact travel with one to UFO conferences, etc.
I will be celebrating New Year at Butterfly Lounge (www.butterflylounge.com),
and I might post here from my hotel room from a TI 707 dialing into
ivan.Harhan.ORG at 300 baud! (And yes, I have the same taste in women
as in computers: I like them both BIG!)
surely SOMEBODY knows how to write a look-up table
program to translate!
Of course it's possible, it's just totally non-standard, and most importantly,
UNIX generally expects the user to have the complete ASCII set available
to him. The V7 tty driver has support for turning an uppercase-only
tty like ASR33 into a terminal with both cases in software, but emulating
full ASCII from the 5-bit TDD code seems like a bit of a stretch.
TDDs are more expensive, and do not have a 24 x 80
screen.
They typically have a single line display, and sometimes an
adding machine width printer.
For what kind of applications would you consider that interface connected
to a timesharing system to be more usable than a personal computer,
or a 24 x 80 screen terminal?
None. I didn't realise that TDDs were that bad, I thought that they were
more or less normal terminals, that's why I asked.
MS
11 Dec
11 Dec
6:48 p.m.
Fred wrote:
the ASR33 TTY is Bell 103 at 300 baud?
Michael wrote:
That's what I've always thought, anyone who
knows otherwise please correct
me.
The ASR33 TTY does 110 baud. Maybe it can be regeared for other
rates, but I'm reasonably certain that it won't work at 300 baud.
Bell 103 uses FSK, so it will work at any baud rate up to 300 (offically)
or 450 (unofficially; I'm not sure how well that really works).
All of the full-duplex 1200 bps and faster dialup modem protocols starting
with Bell 212 and V.22bis use PSK, QAM, or even fancier techniques which
do synchrnous modulation, so the channel bit rate is firmly tied to the
modulation rate. However, the channel bit rate is NOT equal to the baud
rate, because there are more than two symbols, and thus more than one bit
per baud. For example, Bell 212 and V.22bis are 1200 bps, but only 600
baud using two symbols. V.22bis is 2400 bps at 600 baud using four
symbols.
Eric
12 Dec
12 Dec
12:30 a.m.
On Sat, 11 Dec 2004, Michael Sokolov wrote:
Of course it's possible, it's just totally
non-standard, and most importantly,
UNIX generally expects the user to have the complete ASCII set available
to him. The V7 tty driver has support for turning an uppercase-only
tty like ASR33 into a terminal with both cases in software, but emulating
full ASCII from the 5-bit TDD code seems like a bit of a stretch.
You could do two-character sequences... $a $b $c ... to get
the rest of the ASCII set (ugh)
Everyone's got their favorite tty to ascii converter, here's mine:
http://wps.com/projects/Sources/model02.bas
A PIC and a little hardware.
7331
days inactive
7332
days old
2 comments
3 participants
participants (3)
-
eric＠brouhaha.com -
msokolov＠ivan.Harhan.ORG -
tomj＠wps.com