*Sigh* Sorry, you're a little lost. There is no disk drive for the Turbo Game Doctor 4 or 6. Famicom units use the original Nintendo disk drive to load games. Rob REALLY needs to change that caption because it is completely false.
The expansion port on the back of the TGD is for expansion hardware (home made stuff) not a disk drive. There are no disk drives for Famicom Game Doctor units. This 50 pin connector is simply an extension of the cartridge port allowing the unit to interrupt the game and hand control over to attached hardware. The expansion was used with two devices: the Venus Save Card, and a inhouse device allowing Venus to link the TGD6 to a PC/XT (386)
To use a TGD6 you need:
A) Famicom Disk System
B) Games hacked by *VENUS THEMSELVES* for the unit
The order of operations is:
A) Place Disk System RAM adapter on top of the TGD6
B) Turn on system
C) Insert TGD6 game disk (Side A) into FDS
If it loads, it will prompt for you to insert "side B", then "side C" (disk 2, side A) etc until complete. Immediately after that, the game will load. There is no graphical interface and absolutely no way to load games from a floppy diskette.
To get original Venus game disks you'll need to:
A) Buy them (look at eBay, sometimes people think they're normal FDS games)
B) Buy a few of them, learn how to read/write 2.8" Nintendo disks and reverse engineer the disk format. To do this, of course you'll need to understand 6502 assembly and low level hardware to discover the TGD6's different hardware functions.
Because it's insanely hard to find any Game Doctor 2.8 diskettes, and generally pointless since 99% of them died 10 years ago, and even worse when 99% of those games are pre-1988 games, you'll need to make the game disks yourself.