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Date:         Tue, 18 Aug 1992 19:23:00 -0700
From:         "Bryce Carey, CNS,
              Admin. Sys. Group" <CAREY_B@CUBLDR.COLORADO.EDU>
Subject:      Re: TDDs, modems, telecoms, etc....

From:  carey_b@cubldr.colorado.edu

Warning: Incredibly long boring post. Recommended in case of insomnia.

Bosco Keown writes:

>Bryce and Dave -- I read your postings with mixed feelings. Although
>you made some perfectly valid points, I disagree with a lot of them
>mainly because of the environment in which I work and the first--hand
>access which I have to what is happening in the telecommunications
>business. I'll try to explain. This is rather long and late -- I apologize
>for that, but I haven't been anywhere near DEAF-L for ages.

Bosco,
There is always room for disagreement. My disagreement is with your
perspective and a number of your assumptions that grow out of your
perspective. I have a fair amount of first hand knowledge myself.

The issue Dave Windley raised:

Why is it that modems that are sold to enable a computer or ASCII terminal
to communicate with a plain Vanilla TDD are limited to 300 bps speed and
also cost over $300 when 2400 bps modem cards now sell for $39.

You said that no one wants or needs any speed over 300 bps because
it is not feasible for people to read text moving across a one line
tdd display at more than 30 characters per second.

I said:

>>I believe the point of having 2400 bits/sec speed capability is so
>>that people with standard ASCII computer modems can actually call and
>>be called by people with TT (Text Telephones, which supercedes the 'TDD'
>>designation.)

You said:

>Wrong. This simply *wouldn't* work. Period.

Of course I was not saying here that a 2400 bps ASCII modem can
communicate directly with a TDD modem at 45.45 bps. As I described
in detail in a prior post, the tones and codes are quite different.

I think you have misunderstood my meaning. In the context of Dave's
question about Computer TDD modems I am saying that ANY device made
to give deaf people access to telephone systems, (especially text-based
telephone systems like a BBS or electronic mail or this internet) SHOULD
be designed to communicate with the largest installed base of text telephone
equipment. As you say elsewhere in your post, that is definitely the
ASCII modem, and that standard is moving upward from 2400 bps.

My disagreement here is with the attitude you communicate (perhaps
unthinkingly) that modern computer based telecommunications is not
useful to deaf people because they have poor reading skills and already
have a system (designed in 1960) that "works".

I wrote:
>>The issue is definitely NOT how fast one can type, or read. The issue
>>is how much access one has to the vast array of communications devices
>>existing in the world.

You reply:

>Rubbish. At least 90 percent of people who use Textphones have TDDs with
>one line displays and 300 baud max. These can't cope with 2400 baud input
>streams. You have to consider that the average reading speed of most deaf ppl
>in INTERACTIVE phone conversations is much lower than normal. There *is* an
>ergonomical consideration in using 300 baud.

Certainly, MOST deaf people with telecommunications equipment have old
style TDD protocol machines. They cannot afford to dump them and buy
the latest whizzbang laptop computer machines, either.

On the other hand, why should deaf people be locked into a limited
market at high prices? Why should deaf people be buying brand new machines
that restrict their ability to communicate with the MILLIONS of personal
computers and modems being used?  The fact remains that deaf people
have been stuck with a non-standard niche market protocol with the
old style TDD. I am saying it is attitudes like yours that keep us
isolated from the telecommunications revolution.

I am suggesting the application of some imagination to the problem
of increasing the range of access deaf people have via telephone.
Dave Windley is talking about making dual mode modems that can
communicate with 2400 BPS computer systems. Let us figure out how
to ENABLE TDD users rather than DISABLE them. Certainly 2400 bps is
only the rate today; tomorrow it will be FAX and 9600 bps that is
considered the minimum acceptable rate.

I said:

>>The problems you mention with display speed and reading speed are easily
>>dealt with by proper computer buffering of data recieved. The problem
>>with MOST existing TDD is that they are poorly designed. They are limited
>>by assumptions such as you have made that the only speeds necessary are the
>>speeds required by a human typist or reader.

>>Most all TDD built today are built with microprocessor chips. Many of them
>>have memory buffers with scroll-back capability. It is incredibly cheap
>>and easy to include more memory and a smidgen more software in these things
>>to deal with the requirements of a one line display. For that matter, it
>>is also incredibly cheap nowadays to include a multi-line LCD display in
>> TDD.

You reply:

>Well this may be true, but the truth is....
>most deaf people don't need all the bells and whistles....anyway, we are
>talking about INTERACTIVE conversation, with one person able to interrupt
>the other person. Baudot allows this...300 ASCII/CCITT does to some
>extent, but you often get dropped lines. At higher speeds, the handshake
>is going to be too tentative for this.And 4-line LCD displays are
>excruciatingly hard to read unless you're at the right angle and
>your eyes can cope with ridiculously poor contrast.

ASCII communication at full duplex is inherently designed to allow
two way simultaneous communication. The TDD protocol is a hybrid
simplex protocol with no provision AT ALL for the "reading"
party to interrupt the "typing" party. If two people type at the
same time on a TDD link, the result is TOTAL garbage because both
parties are using the identical tone pair to communicate. The Bell
103 (ASCII) modem uses two separate pairs of tones, so that both
parties can type merrily along at the same time with absolutely no loss
of information.

The only complication is to separate the DISPLAY of
what is sent from what is received. This is a trivial software
design problem to solve. Even a single line TDD display could
be split to allow the "reading" party to have a few characters
on the display where "interrruption" messages appear. Again, I say to
apply a little imagination, and do not assume deaf people cannot read.

The fundamental issue in network communications is NOT how fast the
display devices for humans can display the characters. The issue
is how fast the communication link transmits. The display of characters
(or pictures) for human reading is under the control of the equipment that
receives the communications. That is why I mentioned the role of buffering
in communications systems. One cannot transmit characters on an
interactively typed telephone link any faster than one can type them!
The characters may travel at a rate of 2400 bps per character, but
the actual number sent in any second will depend on the typing speed
of the typist.

Let me use an analogy:

When a person speaks, the speech sound waves travel from the
speaker's mouth to the hearer's ear at about 1000 feet per second.
The SPEED OF SOUND does not change when the speaker speaks faster!
BUT if the speed of sound were only 22 feet per second the bandwidth
available for communication would be so low as to make speech comically
inefficient. In other words, one would have to speak V e r y  s l o w l y
at ALL times if the speed of sound were limited to 22 feet per second.
This analogy is directly comparable to a 45.45 bps TDD vs 2400 bps
ASCII modem.

I said:

>Most BBS systems use a start/stop data protocol to control how many
>characters are transmitted at a time. Usually a BBS system is set up to
>transmit a full screen of text at a time, but this is optional. There is
>nothing to prevent a well designed TDD from scrolling one line at a time
>from a memory buffer containing a full screen of lines.

You reply:

>There are factors which prevent this. The main one is economics.
>TDD manufacturers do not make lots of profit because the laws of supply
>and demand, when applied to TDDs, don't allow for very much of a profit
>margin per TDD. So there's little cash to be invested in serious
>development. But lets not get bogged down into what can be done with
>existing technology. It's all defunct anyway. I'll explain later.

The reason that 2400 bps modems are so inexpensive is that they are
made with standard chip sets purchased by the hundreds of thousands from
chip manufacturers. Many different brands of modems use the same basic
modem chips. These modem chips are not expensive to make. One can get
modem chips for less than $10 in reasonable quantities. The cost of a
SINGLE circuit board layout is also very low. One can make a printed
circuit board design and have it produced for around $40 in single board
quantity (much MUCH less in volumes of 100's).

The largest single costs in making a device like a modem are in the
requirement for FCC regulatory testing and compliance licensing.
Some modem chips include the special regulatory circuit required by the
telephone system interface, so one can avoid some of the licensing
costs by paying a premium for the modem chip.

In addition there will be market packaging costs (the injection
molds for plastic cases are expensive to create) and advertising/
distribution costs. These costs are pretty much constant no matter who
is building and selling a product.

Of course there will always be a limited market if TDD manufacturers make
junky and expensive systems that are of use only to deaf people who are
stuck with no migration path to better equipment.

I said:

>>Dave Windley's comment was that the COMPUTER modems built that work with
>>old style 45.45 bps and also work with ASCII codes are mostly built
>>with a top speed of 300 bps. When one pays $300-$400 for a modem nowadays
>>one expects to get at least 9600 bps and FAX modem capability PLUS
>>special error correction and data compression protocol converters.
>>There is really NO REASON AT ALL that the hot shot ASCII modems
>>could not be made to work with 45.45 bps TDD standards if there were
>>a market demand from deaf people for such things.

You said:

>No company is prepared to reverse--engineer their products for retro--
>compatibility like this. It's just not cost--effective.

EXACTLY MY POINT! Design it in in the first place. The only way that
people who make modems for large scale markets are going to design
in an option for TDD compatability is if DEAF people speak up
and make it clear there is a market. The modem market is HIGHLY
competitive and design of modems is based on standard chip sets.
If someone sees a real market for TDD at 45.45 speeds (perhaps
driven by requirements from the ADA) they will design an enhancement
to their modem boards to include TDD options. OR if one of the TDD
companies saw a real demand from their deaf customers they could easily
re-program their microprocessors.

I said:

>>MOST high speed modems such as 2400 bps modems and up are built with
>>microprocessors in them to handle the code protocols required. These
>>modems are now in the under $100 price range. Windley's comment is
>>that most (?all?) TDD compatable modems STILL sell for $300 on up.
>>Why the difference? Is it a conspiracy to keep the deaf poor and
>>technologically backward? No, I think it is simply a lack of
>>foresight and imagination on the part of those who design these
>>things for the market.

You emphasize my point nicely when you say:

>The difference is (again) economics of scale: the law of supply and demand
>dictates the price of modems and tdds....currently there is a far
>greater demand for stand-alone and card modems of all kinds, but
>the demand for tdds is relatively low...and the manufacturing process
>for tdds is relatively expensive...foresight and imagination don't
>count for much when you have trouble enough making a profit in the
>first place.

What I am criticizing in your perspective is that you seem too hasty
to assume that the way things work NOW is the way they must continue to work.
Both Dave Windley and I are proposing changes for the better. While you do
not oppose the idea of change for the better, you DO stomp the suggestions
into the ground with your dismissive tone.

>>Bosco, you work for IBM. Why not make this suggestion to your designers?

>Ay, there's the rub. But we aren't working on this. I actually
>work in the Networking Systems part of IBM's business, and a lot of
>the work being done here is actually on computer-based telephony, personal
>and desktop videoconferencing. The trend with IBM and the Telecommunication
>Companies (e.g. British Telecom) is in the development of global high-speed
>networks which support data, video, and voice. I am pretty confident that
>a 5 year span will see these technologies become widespread, and so TDDs
>will more or less become obsolete. So there's very little to be gained from
>improving existing TDD technology.
>
>In fact, BT have just announced a far--reaching plan for a global high-speed,
>high-bandwidth data/video/voice global network. Say goodbye to the humble
>TDD, folks. In 5-10 years, everyone will have their own portable personal
>communications thingy which will allow people to type to each other/talk
>to each other/send each other data/see each other, all at the same time.
>I *guarantee* it.


That is all very good. I do not doubt that we will see all sorts of
neat telephony systems in the next five years. I'm designing a few.
I personally expect that The old style TDD machine standard will slowly
become obsolete. BUT it will not be easy for most deaf people to afford
to buy expensive new telephone systems.

Worse, unless people like you, Bosco, make the point to your designers
RIGHT THIS VERY MINUTE that they need to provide a migration path for people
who have old TDD to the brave new worlds you are designing, you
will once again cast deaf people into a technological communications ghetto.
We will see a division between people who can afford new style communications
and people who cannot that is comparable to the division between
successful oral deaf and people who, for whatever reason, cannot speak.

It is highly necessary that people designing systems for world wide use
keep in mind that some of us need a few minor design adaptations so
that we can also use these systems. It is not cost effective to design
special weird equipment for a minor market of disabled people, but
it is almost trivial and free to design features useable by disabled
populations into NEW products for the hearing mass market.

Hummmmmm.... I have been disagreeing with you pretty strongly, but
mostly by repeating myself in the belief that I may not have been
clear in the first post. It might be apparent from this post that
I have been working to change things. I am not talking about
OTHER (unnamed) people doing "something" I am actively thinking
through HOW to resolve many of these problems.

Perhaps I am wrong in some of MY analyses. But I cannot help feeling a
strong reaction to what I experience as a too facile rejection of positive
suggestions. In other words, this is a personal thing to me.

In sum, my biggest complaint is your rejection of the idea that deaf
people have anything to gain from moving along to the use of modern
ASCII telecommunications standards and speeds such as Dave suggested.

I detest the idea of sitting around waiting for some good wise powerful
beings to bestow wonderful technological nirvanas when we have the
ability right at hand to move towards self-help.

Self-help in this case means that technically sophisticated and educated
deaf folk like us should be showing the way to better things, not
condescendingly saying "oh, the TDD is good enough for you, no need to
change anything. Don't even bother your little heads about it. Just wait
until we get X technology and it's going to solve your problems."

Deaf people need to make intelligent efforts to escape communication
ghettos BEFORE the foundation walls are laid, EXACTLY because it is
expensive and difficult to change things after they have been designed for
mass market production and use by hearing people. This same idea applies
to any group of minority people. (Such as the blind, who are not going
to enjoy picture telephones.)

My apologies if I have been tactlessly blunt. Perhaps I am just too
emotionally involved in this technical market issue.

-Bryce