In previous messages, Josh Dersch <derschjo at msu.edu> said: Josh... The "secondary" drive is an 8 inch hard drive. It is VERY similar to the 5.25 MFM drives we have all used on various machines, but there are a couple of differences: 1) The 'control' connector is 50 pins, not 34. This is the 'common' connector that is connected to every drive. 2) The 'data' connector (both are 20 pins) uses positive and negative voltages (a 10 volt swing) for the differential data. Some drives even decode the clock drive. 3) The 8 inch drives use +24 volts, +5 volts, and -5 volts, and some drives use line voltage (120v/220v, etc.) for the motor drive. 4) The rotational speed of the disk is 3000 RPM, whereas the 5.25 drive is 3600 rpm. This means that the data rate for MFM is lower for the 8 inch drive (usually the crystal is 8.666 MHz, not 10 MHz for the same rotational bit density). That being the case, adapters can be made, if you can re-clock the drive controller. Now back to the TRS-80 problem at hand. The box you have is just a container for the drive proper. I doubt that much more is inside the box than the drive and a power supply. The controller is in the "primary" drive box, and is similar in function to a PC's controller at the register level (both were designed by Western Digital). I don't remember if the TRS-80 used 256 byte sectors, or 512 (what the PC uses) byte sectors. It needed an interface board that plugged in the backplane of the Model 16. I built up a "primary" disk box myself using the controller that works with the 5.25 inch drives, using my own 5.25 inch drives. The controller was limited to no more than 8 heads due to the way it was designed (they hadn't made XT2190's yet!). It worked OK. Later on in the Model 16/6000 time span, they built up a single board that plugged into the backplane of the TRS-80 Model 16 (6000) that was the full controller. By that time the only drives being produced were 5.25 inch ones, so that conformed to that interface (34 Pin control, 20 Pin data). It is interesting to note that the drives used by Radio Shack had another "feature" in that they connected a "drive selected" line on the Data connector. This was used so that they didn't need to worry about where they were plugged in. If the connector was "selected" (had the true signal), it had the data. If you get a controller this may need to be taken into account. Other than that, you have a "nice box". Good luck. -- Tom Watson tsw at johana.com ____________________________________________________________________________________ Finding fabulous fares is fun. Let Yahoo! FareChase search your favorite travel sites to find flight and hotel bargains. http://farechase.yahoo.com/promo-generic-14795097