I don't know this particular unit, but this sounds like a 'drive exerciser', and I have one of those. A drive exerciser basically simulates the host interface to a floppy drive. It lets you select the drive, load the heads, step the heads in and out (good ones lwt you go to particualr tracks directly, move the heads and forth automatially, etc). It'll monitor the write protect, inde, track 0, etc lines and display them on front panel LEDs. Most of them also let you write a continuous square wave at a couple of selected frequencies to the currently selected track. But you do need a 'scope to use one. FIrstly to look at the waveform read back form the disk (e,g, after writing one of those test frequencies), and secondly to do the alignment. Typically to do the 'radial alignment' (gettign the head on the centre of the track, what most people mean by 'alignment' here), you put the alignment disk in, move the heads to the CE track using the exerciser, then monitor the outputs of the read amplifier in the drive (2 testpoint on the drive PCB) with a 'scope and move the stepper motor or whatever until the 2 loes of the CE pattern are the same szie. If you don't have a 'scope, there was a thing sold in the UK (designed over here too I think) called a 'Microtest'. You used that with a PC (the minimum spec, was I believe, 256K RAM, 1 serial port, 8088, any video card, even MDA). You linked up the drive-under-test as drive B to the PC (there were cables included with the Microtest unit for this), connected the Microtest box to the serial port (this was a box containing a microcontroller, ADC chip, etc, and which drew poer from the RS232 port) and ran the Micortest software on the PCB. You then selected the drive type from a menu of about 300 types, and it displayed a picture of the drive PCB on the screen (using the IBM block graphics characters) and told you where to connect 5 leads coming from the Microtest box. You then put a stnadard alignment disk in the drive. If, say, you wanted to do the radial alignment, you presss the approrpiate function key, the ehads moved to the right track, and the mcirotest unit effectively measured the amplitude of the 2 CE lobes. The result was displayed on the PC (again using IBM graphics chracters) as was the distance that the head was from the right position, and whether it was in tolerance. You moved the head stepper until it was where it should be. What do I use? Both :-). The Microtest (I was given one) is useful for quick test and alignments on basically working drives. The exerciser is useful to figuring out why the heads won'y move in the first place, or why the write cirucit is blowing transistors, or... -tony