Texas Instruments TI-89 Tip List page 461

goes by the pseudonym E.W. has written an equation writer for the TI-89 / TI-92 Plus. Two versions
are available: a free version, and a for-pay flash application. The flash application includes additional
features and functions.
errornum
A system variable which contains the number of the most recent error. errornum is zero if no errors
have occurred, or if ClrErr has been executed.
expression
A combination of variables and, optionally, operators and functions. For example, a+b, sin(x) and y are
all expressions.
false
A built-in system variable which indicates the Boolean 'false' value.
file extension
This is a three character suffix on the names of files stored on a personal computer. The following table
shows the file extensions for the TI-89 and TI-92 Plus.
TI-89
n/a
.89c
.89d
.89e
.89f
.89g
.89i
.89k
.89l
.89m
.89p
.89q
.89r
.89s
.89t
.89u
n/a
flash application or flash app
An application that can run directly from flash memory, without first being copied into RAM. Flash
applications can only be created with the TI SDK and by obtaining a certificate from TI. Certificates are
not free; TI charges for them. Flash applications are started from the [DIAMOND] [APPS] key.
flash; flash ROM
flash is a short way to say flash EEPROM, which is one of the two types of memory on the TI-89/TI-92
Plus: the other type of memory is RAM. 'EEPROM' is an abbreviation for electrically erasable
programmable read-only memory. You can store programs and variables from RAM to flash with the
archive operation, which frees up RAM for calculations. The contents of FLASH can be quickly read,
but it takes more time to write to the flash memory. The contents of flash memory are retained if the
batteries are discharged or removed. See also RAM.
Flash memory has a limited (but large) number of erase/write cycles. The rating for the TI flash
TI-92 Plus Description
.9xa Geometry figure (constructions)
.9xc Data variable
.9xd GDB (Graph database)
.9xe Expression (numbers, equations, etc)
.9xf Function (Y-vars, user-defined functions)
.9xg Group
.9xi Picture
.9xk Flash Application Software
.9xl List
.9xm Matrix
.9xp Program
.9xq Certificate
.9xr Lab report
.9xs String variable
.9xt Text variable
.9xu Operating system
.9xx Geometry macro
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