TPDD client

A "TPDD client", also usually called a DOS(note), is software that runs on the portable and can read and write files on a Tandy Portable Disk Drive or Tandy Portable Disk Drive 2, or any of their rebadged versions like Brother FB-100 and Purple Computing disk drive, or any "TPDD server", software which runs on a pc and emulates a TPDD.

To use a real TPDD or TPDD2, you need the special cable that came with the drive, or a new cable that has the same electronics inside.

TPDD#Cable

https://github.com/bkw777/TPDD_Cable

https://www.arcadeshopper.com/wp/?page_id=11#!/Special-serial-cable-for-Tandy-Portable-Disk-Drive-and-Tandy-Portable-Disk-Drive-2/p/144969001/category=28313042

To use a TPDD server aka emulator, you need a different special serial cable.

Model_T_Serial_Cable

Here are some of the major DOS's for Model T computers:

• floppy - The official DOS that came with the TPDD
• flopy2 - The official DOS that came with the TPDD2
• TS-DOS - Commercial DOS from Travelling Software. Now free.
• Tiny - A tiny DOS
• Teeny - An even smaller version of Tiny, and the smallest DOS
• DSKMGR - An early alternative DOS. One of the only things available for Kyotronic KC-85 and Olivetti M-10.
• Power-DOS / Power-Disk - An early alternative DOS that is more full-featured and composed of a collection of several utilities, almost like a normal disk operating system like cp/m or ms-dos.
• Disk+ - Commercial DOS option ROM from PCSG.
• Disk Power - Commercial DOS from Ultrasoft Innovations. Requires original distribution disk to install.

(note) Not MS-DOS. The generic term for any disk operating system.