Trouble Imaging CP/M 5.25” SSSD Disks — No Flux Data Captured

[Tech]

I’m trying to preserve CP/M 5.25” single-sided, single-density floppy disks, which read and write well on the original CP/M computer.

Out of the four 5.25” drives I have, three display the message “no index pulse found” when attempting to read the disks using the SCP Disk Analyzer. When I select “Ignore Index Sensor” from the options menu, the software proceeds to read—but I still get no flux data.

The only drive that can read the disks without ignoring the index sensor also produces no flux data.

Below are screenshots showing the flux display for head 0 and head 1.





I’m wondering how I can successfully image these old disks. Any help would be greatly appreciated!

[Tech]

The floppy drive in the CP/M computer is MPI B51. The manual says in SSSD mode, the drive's Transfer Rate is 125K Bits/Sec FM encoding. Could this the reason my SCP can't read the disks because it expects 250kbps transfer rate?

[admin]

The data rate doesn't matter - it's not used for anything except for decoding. Your drive is not physically reading the disks. This is why you get red at the bottom like that - nothing is being returned (static), like the disk is not formatted.

[Tech]

Strange! I'm comparing the two drives (the original MPI B51 and TEAC FD-55B connected to SCP) and don't see why they are not compatible!

Code:

                        MPI B51         TEAC FD-55B
Transfer Rate (FM)      125 kbps        125 kbps
Tracks                  35 or 40        80
Track Density           48 TPI          48 TPI
Rotational Speed        300 rpm         300 rpm
Average Latency         100 msec        93 msec
Recording Density       2580 BPI        2938 BPI
Data Flux Density       5160 fei        5876 frpi
Data Capacity (Unformatted):
  Track Capacity        3.13 kB         3.125 kB
  All Tracks            125 kB          250 kB

[admin]

I would say the drive, cable, or the SuperCard Pro are bad. Even an unformatted disk will give you data, just lots of "snow".

It is possible that if you ever plugged the floppy cable in backwards that you have destroyed the SuperCard Pro board. Common symptoms are just like what you describe, especially with the NO INDEX PULSE message.

Take a high resolution picture of the two buffer chips (HUEY and DUEY). There should be no burn spots, or deformities on these chips. Post the picture here and I can have a look. You can also send it to data @ cbnstuff.com