Texas Instruments is the greatest company ever; they make logic chips, processor chips & even consumer products such as calculators & computer systems. However, their greatest achievement is the graphic calculator.
All that's needed is an actual TI calculator, linking software, a TI calculator ROM dumper & a TI calculator emulator.
In this tutorial, the used calculator will be a TI-83, the used linking software will be TI-Graph Link, the used ROM dumper will be ROM Dumper v2.2 & the used emulator will be Virtual TI.
First, install TI-Graph Link onto the computer. It should have come on a CD with the calculator & a calculator-to-serial port adapter. Once the linking software has been installed, connect the calculator to the adapter & the adapter to the serial port of the computer. Don't forget to turn on the calculator.
Next, download ROM Dumper v2.2 here or in the Downloads page. Extract the archive & run the TI Graph Link program. Use TI Graph Link to send the file "Rom83.83p " to the TI-83 calculator (this is an application that runs on the calculator, also called ROM Dumper, which allows communication between the computer & the calculator to happen). Then, open an MS-DOS window (or log into MS-DOS) & run the program "romdump.exe" (ROM Dumper v2.2) in the following way:
C:\>romdump [filename] [size] [COM port]
Where [filename] is the name of the resulting *.rom file, [size] is the size of the file & [COM port] is the actual serial port's designation number (i.e.: COM1, COM2, etc). Refer to the file "romdump.txt" for the proper file sizes according to the calculator model (this text file is included with the download for ROM Dumper v2.2).
Next, run ROM Dumper on the calculator (it will appear as a new menu heading in the calculator when either the "APPS" button or the "PRGM" button is pressed).
The programs on the calculator & on the computer will communicate to each other & create a file with the filename *.rom (where * refers to anything that the file is named as). Lastly, download the emulator called Virtual TI from here or the Downloads page, copy the ROM file to the same directory as the emulator & run the program "Vti.exe." Select the calculator whose ROM is in the directory (in this case, select the TI-83 calculator) & a calculator will appear on the computer screen!
Now, the computer will have all the functions of the TI-83, including the graphics, graphing abilities & the numeric accuracy of the original calculator.
For users of TI-82, TI-85 or TI-86 calculators, use the above steps to copy the calculator's system information, except for one thing; send the file named "Rom82.82p" to the calculator if using a TI-82, "Rom85.85s" if using a TI-85 or "Rom86.86p" if using a TI-86.