Thought you'd get a kick out of this. Very simple actually.
- Download and install a copy of OpenOffice/LibreOffice on your PC and open whatever excel file you need to port.
- Then "Save As" in the SYLK format. This stands for Symbolic Link File Format.
- Open up ti99dir and copy that file to a disk image. You want to do this as Int/Fix, 128, and Binary File (no conversion).
- Make a diskette or an .HFE image (if you are using a Lotharek).
- Fire up MS Multiplan on the TI-99 and press T (for transfer), and O (for options). Set the file type as SYLK. You can also specify the location of your data drive in the form "DSKx." (but not as part of the filename, it has to be set under options in the field just below the file type selector)
- Press T, then L (for load) and enter the filename. Prepare to wait. After about a minute you'll see it processing SYLK lines as the data is fed into Multiplan.
- Done - go to T (Transfer), then O (Options) -set file type as Normal and then T, F, Save to save your Multiplan file.
- Go nuts - slowly...
Obviously, your spreadsheets need to be dirt simple - I didn't test this with formulas but it should be able to handle basic A1 to R1C1 formula conversions.