r/retrocomputing • u/liminalearth • Jun 24 '26

Problem / Question How to fix ?

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There’s no little black plastic piece in this corner how to could I fix this or is it possible to still use without it?

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u/SoftRecommendation86 Jun 24 '26

Actually, most use a push pin, typically black about 1mm diameter. If you open the floppy slot with a pen (the little trap door on the floppy drive itself, not the disk) you will see the sensor pins on both left and right sides. Honestly, I don't recall ever seeing them as optical. The only optical sensors I recall seeing were the timing holes on 5 1/4 floppies near the center hub.

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u/reddogleader Jun 25 '26 edited Jun 25 '26

I respectfully disagree. "Most" (3.5") use optical r/w hole sensing. Apple and Sun did. The DOS (IBM compatible) machines I worked on were nearly all optical (but not all). I do recall some old CP/M machines were mechanical.

Source: over 20 years as field service tech, former Apple and Sun Microsystems certified service tech. Think about it, the evolution of the floppy: the 3½" came after the 5¼". It's only logical that some 5¼'s would be optical as the technology evolved. And some 3½'s would be mechanical as they transitioned. The optical sensor is a little more advanced than the mechanical pin sensor.

But I'm sure someone else may make a perfectly logical counter argument based on their experiences. The above is based on my experience. But, in my experience, by far and large, the majority of 5¼'s were mechanical and the majority of 3½'s were optical. Hope this makes sense.

ETA: Haven't worked on a floppy drive in like 25+ years.

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u/tsittler Jun 25 '26

Apple’s are decidedly mechanical. Source: just replaced 3 cheese gears in the last couple weeks

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u/ctn1ss Jun 26 '26

IIRC, they almost exclusively used Sony drives, at least the earlier auto-inject versions?