Directory Track Reader

The following program was written on an old model Zebra Disk Drive. Owners of the-newer FDD 3000 may wish to run this program and report on the results. I don’t know whether there are any software differences between the two models.

The disk drive controller formats the 3 inch disk into 40 tracks, numbered 0 to 39; each containing 4K bytes. Each track is subdivided into 16 sectors, numbered 0 to 15; each containing 1/4K or 256 bytes. The first four tracks (0 to 3) are reserved for the operating system. Track 4 contains the directory. Tracks 3 through 39 contain the files you saved to disk. When a disk is initially formatted, TOS sets up 40 tracks, writes a copy of TOS to tracks 0 through 3, places the disk name in the first sector of track 4 and sets all unused bytes to 0E5h (229d).

The Zebra Disk Drive-Technical Manual remarks that the contents of the directory track can be read using the extended Basic command INPUT #0. After some trial and error. I found a suitable method to read this track using a Basic program.

I numbered this program beginning with line 200. You may wish to merge this program with a utility program which reads disk headers. One such program is Chuck Dawson’s DISKREAD, which was published in Vol.1,. No.1, of the (now defunct) T.0.P.S. newsletter. DISKREAD, or a similar utility, could be used to obtain further details on the directory contents.