Creating a "125kHz test pattern"
I am troubleshooting a TRS-80 floppy drive controller and the test procedure calls for me to:

Quote:Insert a diskette that [h]as a 125kHz (2F) pattern on track 00 into the Disk Drive and close the door. NOTE: The Dysan 224/2A Analog Alignment Diskette has a 125kHz pattern on track 00. The program will turn On Drive 1, set the head to track 00, continuously read the track and display the number that is read, which should be 255.

I found the recent thread on Alignment floppies in general and understand that I wouldn't be able to recreate such a floppy in full, but I'm wondering if I can specifically write just the specific test pattern this calls for.

Since it seems to just be a constantly repeated pattern, I thought maybe I could just write all the same byte to a raw 360KB file disk image and then convert that to a floppy with SCP. But I'm a little confused as to what byte that would be — it calls it a "125kHz (2F) pattern" but the value expected to be read out is FFh rather than 2Fh.
That is either the FM or MFM pattern, not the flux data. If this track is just a simple test pattern on track 0, then it could be duplicated with the SCP hardware Dysan and other alignment disks have other tracks there are elliptical as well as tightly grouped (higher TPI) in sections that can not be duplicated with a standard floppy drive.
Sorry, to be clear I do *not* own any alignment disk, so I am starting from scratch (nothing I can duplicate myself unless someone can share flux files from theirs).

If I fill in a track using the Analyzer/Editor tool with all FF bytes and write as FM [which based on the commands run during the test procedure I think is what's expected, i.e. the controller is told to read a track while in single density mode] the resulting flux that it writes will end up similar to a 125kHz signal? Why does the guide call it a "2F" pattern?
You would need to fill using flux mode. I am not sure what a 125KHz signal is suppose to mean. That typically would be a 8us pulse. If that is correct, you could try filling with 0140. That is 8000ns (8us) of time for the SuperCard Pro.

Users browsing this thread: 1 Guest(s)