jltursan noted some challenges trying to recreate the Lynx DOS interface and Lynx FDC:
Not really; but to make a long story short:
- I've built a Lynx DOS proto based on Frank Rasmussen design (I assume it works, he has pictured his own working setup)
- Both PCBs (interface & controller) seems to work, XROM loads the Disk ROM as expected and the Lynx still works
- Seems that I can format a floppy, I can hear the stepper motor moving the heads along all the expected tracks.
- ...but when the floppy is going to be verified, it always fails. IIRC, the floppy was indeed erased so seems that there's some problem when reading.
I've checked both floppy drive types: 5.25" and 3.5" (funny that when a 3." drive is used, it writes 80 tracks instead the usual 40). I've also checked all the ICs and all seems to be good working ones, the FDC also seems good, checked both 1793 and 8877 models. My only guess is there's some kind of FDC calibration problem that I'm not able to correct...or maybe my Lynx has a strange problem and need to test my LynxDOS with another machine
Here is what I find interesting.
I have a genuine Lynx DOS interface and Lynx FDC. I have two genuine Lynx 200K floppy drives.
I never planed to use real 5.25 floppy disks. I have an HxC floppy disk emulator that is much simpler. Also the Lynx floppy drives have a hard wired 220V power supply that is heavy, and even though I have a 220V step up transformer, its a lot of spaghetti. That said:
I did check to see if the floppy drives worked. I formatted a blank disk. The drive stepped through the tracks, then the head returned to track 0, and Lynx DOS reported an error. I figured the drives were probably bad, removed the FDC board, and connected it to the HxC.
The Lynx will not format a HxC/HFE disk. Again I hear the unit "stepping", it completes, goes to verify, and reports the disk is bad. I just assumed the LDF implementation was iffy and just recycled old LDF images by deleting the files and starting over. That works.
But I never connected these two events until jltursan reported the problem with his Lynx DOS/FDC design.
Also, the Lynx will NOT write anything to the HFE disk unless I force pin 34 low (short it). The HxC device works fine with the Amiga, ST and an old XT, so I think the HxC is fine. The Lynx FDC just seems supper fussy on the RDY line.
So having said all of that - jltursan - have you tried using your DOS/FDC with an HxC or Gotek and seeing if it will read? is there just something really wierd about the Lynx DOS/FDC implementation? Has anyone got a working Lynx disk drive that can reliably format?
