On the earlier TI graphing calculators (such as the TI-82 and TI-85), the
standard amount of memory (usually around 28K) can easily be used up with
programs consuming several kilobytes apiece. While the more recent models
have 5 times as much memory (or more), memory is still rather scarce.
Homemade memory expanders are add-on devices that let you make use of
additional storage beyond your calculator's memory. While programs must
typically be copied back from the external storage before use, expanders not
only have greater capacity than a calculator but can also act as a backup in
case your calculator's memory is erased.
» Expander 2
The Expander II is a memory expander device that adds 512K memory to any TI graphing calculator that has a link port and the driver software. The cost is about $40. Currently there are drivers and software programs for the TI-85, TI-86, and TI-92.
The Voyage 200 has 2.7 MB of flash memory, but only 1 MB is available for the user as archive space. With Xpand by Olivier Armand, all of it can now be used as archive memory. Xpand patches your operating system to allow full usage of the flash without interfering with the ability to install flash applications.
» Pterodactyl Memory Expander
Pterodactyl is a specific expander for the TI-86. When used it adds an additional 15kb of memory to your calculator. There is some incompatibilty issues with certain ASM programs, however it works flawlessly with BASIC programs. Kirk explained it best when asked how he found the extra memory, "TI allocated 16kb of RAM for temporary storage during normal usage of the calculator. However, nowhere near this amount of space is utilized." This program will utilize most of the RAM that is never even used.
» MaxMem v2.30
Contrary to what TI says, their first TI-89 calculators (HW1) aren't
archive memory. This program allows you to have as much memory as a HW2, 640 kb. This program is also should be used cautiously and only on a stable calculator.