First impressions of the TI-89
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First impressions of the TI-89
Thanks to tips posted on this list, I got in my order for a TI-89 to
Calculators, Inc. last week before they sold out. Yesterday when I got home,
guess what was waiting on my doorstep? I've talked to all the retailers in town
here (I think) and none of them have any idea when they will be getting a
shipment in, so maybe mine is the first TI-89 in Rochester.
It didn't take me but a minute to decide that the display is a big improvement
over that on the 92, even though the screen is so much smaller. The sharpness
and high contrast make up for the tiny size of some of the characters on the
screen and the symbols printed on and around the keys. At worst I need to reach
for my bifocals occasionally, rather than straining my eyes continually and
tipping the calculator back and forth as I find I need to do with my TI-92 no
matter how I change the contrast setting. Of course more paging will be
necessary to view long inputs and results, but I expect a statistical analysis
would show that for almost all users short inputs and results will predominate
in actual use.
TI was very clever in squeezing down the 75+ keys on the TI-92 to only 50 or so
in the TI-89. I like the crisp feel of the keyboard, and find that the
"travel" between important keys has been reduced to some extent. Some
significant changes here in that EE and, more important, the "with"
substitution symbol | now get their own keys. Each of the letters x, y, z and t
get their own special key, with the others parceled out among other keys to be
accessed by a special, purple _alpha_ key. Entering quantities of text with
this arrangement is going to require its own special training cycle. Also, I
miss the "theta" key. And I still miss a squaring key. Ti has gone further with
this model, and now there is no access at all to the operation of reciprocation
-- it has to be built from other operations. This may be considered a design
mistake by a significant number of users. Well, the calculator _does_ fit
nicely in one hand!
One more addition to the keyboard is a HOME key all by itself, without needing
a diamond combination. This probably recognizes the frequency with which users
want to get back to the home screen in a hurry. There is also a corresponding
DispHome command in the built-in language, one of the improvements added in
the TI-92+ upgrade. In general there seems to exist a strong correspondence
(except, as noted, for geometrical work) between what the TI-92+ will do and
what the TI-89 will do. For example, base conversion and capabilities for
working with units -- neither features of the original Ti-92 but obviously
heavily requested by users -- are there.
I haven't investigated the symbolic algebra/trig/calculus capabilities of the
TI-89 extensively as yet, but there seem to be some differences from the TI-92.
On the 92, an entry of (m-n)/(sqrt(m)+sqrt(n)) is immediately simplified to
sqrt(m) - sqrt(n), while the TI-89 will not do this unless encouraged by an
"expand" command. In general, though, algebraic calculations with radicals are
tricky, and it is hard to know just what an algebraic system "should" do. I
would like to be able, sometimes, to rationalize the denominator in an
expression such as (sqrt(m) - sqrt(n))^-1 , but do not offhand know how I can
ask the calculator to do this. Anyone have a suggestion?
RWW Taylor
National Technical Institute for the Deaf
Rochester Institute of Technology
Rochester NY 14623
>>>> The plural of mongoose begins with p. <<<<
there seem to be some difference