Tuesday, September 23, 2014

CE Disk Cartridge inspected: not usable - surfaces too damaged


I realized that with the markings that were visible through the cartridge door, it was essential that I open up the cartridge, inspect it and clean it if it can be used in the drive. I unscrewed the bottom plate and opened up the container. Immediately, I could see scoring, scratches that glinted because they were deep enough to expose the aluminum substrate of the platter. Oh dear.

Cartridge open, platter visible for inspection and cleaning
Top cover of the cartridge, with platter removed
Circular scratches fill an area somewhere near where the CE information was recorded, rendering it unusable because any heads flying on this pack would be damaged. I took several pictures looking at the scratches, plus the dark circular area on the other surface which may be rubbing wear but does not show the aluminum at the base. 

Scratched through to the aluminum underneath

Another view of the scatches

Evidence of one scratch beginning, where a particle jammed between head and disk temporarily

other surface, dark rub marks
 In addition to the scratches, there are quite a few spots were some contaminant settled on the platter and affected the material. These may be water spots or other materials, but if they altered the surface it might be uneven enough to cause head-disk interference and a crash. One set seemed to have removed quite a bit of the binder, showing some of the bare metal underneath.

Melting away the binder and magnetic material

Contaminant spot

Spray of drops across left to right, affecting surface

More streaks of contaminant across surface, top to bottom


  1. uggh - hope you didn't pay too much! Wonder if you could use a DEC RK pack?

  2. Hi Jack. Well, I did pay a bit of a premium, especially since I have about four dozen normal cartridges already.
    I have three RK05 drives and several RK05 cartridges. The carts vary based on the slots cut around the metal based that spins on the spindle - these define how many sectors exist around a track. The 1130 has eight cuts but the drive ignores every other slot, thus implements four sectors. The DEC drives implement 8 or 12 sectors on a track.

    I believe that a bit of added hardware could convert the slots on both types of RK05 cartridges to the eight pulses timed for the IBM disk drive, allowing it to read and write 4 sectors on those packs. I had designed it to use the RK05s as a 2310 substitute for my 1130 replica machine, having investigated it quite a bit. I don't think I could make use of an RK05 CE pack equivalent.


  3. I had also looked at the possibility of using DEC packs but I believe the bit density of the RK05 was 2200 per inch, which is much higher than that used by the IBM. This would indicate either a better (i.e. different) type of oxide and / or a different head type meaning they are unlikely to be usable for that reason anyway.

  4. I concur, Peter. My plan was to create a parallel set of drives and cartridges, based on DEC, for my 1130 replica, that would hold the same data in the same format, but would not be cross compatible with 2310s. I expected to write and read DEC cartridges on RK05s that emulated the disk drive for the replica 1130, but those couldn't be used with the IBM drives in the 1131.