Thursday, May 3, 2018

Labeled the 1053 emulator, looking into repair of IBM 2310 compatible disk drive heads


I dug out my labeling system and produced labels for the console printer emulator box. The process involves printing images on a laser printer, fusing colored mylar film to the toner, bonding clear mylar over the printed image, dissolving away the original paper, then adding adhesive and rubbing the letters onto their final surface. 

Newly labeled emulator box


My IBM 1130 system had as an accessory a cabinet with a Diablo disk drive installed. This drive was the rare standard density version, so called because the original disk drive that spawned all the single cartridge drives was the IBM 2310 drive that is built into the 1130. The 2310 drive was a 1MB capacity drive using chrome covered recording heads operating at 1100 bit per inch density.

My diablo drive also operates at 1100 bpi for compatibility with the 2310. Both use 203 tracks, heads on both top and bottom surfaces, and sector pulses to divide one rotation of the disk into multiple sections. The 1130 implements four sectors of 321 words (642 bytes) although the actual disk cartridge has 8 sector marks per rotation. The 1130 ignores every other pulse to make use of just four logical sectors.

The companies which had licensed the 2310 disk drive patents began to improve upon the IBM implementation in a number of ways, such as faster seeking and higher capacities. The high density version of the Diablo drive records at 2200 bpi, thus doubling the capacity of a cartridge while using the same 203 tracks and two surfaces. Almost every Diablo drive is a high density version, incompatible with the original IBM 2310 and standard density Diablo drives.

All alignment cartridges produced by Diablo have recorded patterns for both standard and high density drives, thus I can make use of the alignment cartridges we have to adjust my standard density drive, once the heads are repaired. They suffered a bad crash, scratching the surface of the chrome.

Most damaged of the two heads
The high density drives replaced the chrome with ceramic, which does not gouge the same way that the original heads did. We have been able to clean ceramic high density heads and put them back into surface regardless of the nature of the disk crash they suffered. Not so with my chrome heads.

Head with more moderate scratching
I will examine them under the microscopes to evaluate the possibility of rehabilitating them. I have a chrome head from a different disk drive type, relatively unscratched, as a comparison. My hope is that the surface can be repaired and the disk drive put back into service as my number two drive on the IBM 1130. 

Relatively good head for comparison

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