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IBM Screws

Indeed, this is one of the reasons I am here. The level of expertise available is amazing, especially on such esoteric matters as nylon thumbscrews (ouch!) and how to pilot an 8" drive through a storm in December. :D
 
MikeS said:
Pshaw! Practically the same as a 5 1/4HD drive with just a couple of little wrinkles.
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Riiiiiiiiiiiiiiiggggggggggghhhhhhhhhhhhhhttttttttttttttttttt! :)

Although, I must admit seeing the 8" floppies for the first time in "WarGames" was damn cool!
 
Mike is right, however. Most of the difference is in the connector. While there are a few drives that use DC spindle motors, most 8" drives use line-powered AC motors, so there's no "motor enable" line. And most 8" drives use a head-load mechanism, but this can be activated by the "motor enable" line that's not used.

Other than not having a "disk changed" status ("ready" is used instead) line, the drive looks a lot like a 1.2MB 5.25" drive, with the exception that it has only 77 cylinders.

Oh, and you'll usually need not only the AC line, but also +24V on the power supply in addition to +5 (some older drives also require -5). +12 isn't used.
 
Most of the drives I've seen for sale have a bundle of snipped wires. I assume they are the power supply connection. That's probably easy to figure out, but the form factor and construction details of a computer will be a little more involved if you have to accommodate a second power supply in the whole thing. IOW, you can't just connect an 8" drive like you would a 5 1/4. You have to first find or build a 24 volt source. I am quite capable of doing this, but you can't compare that to just plugging in a 5 1/4.
 
Ole Juul said:
Most of the drives I've seen for sale have a bundle of snipped wires. I assume they are the power supply connection. That's probably easy to figure out, but the form factor and construction details of a computer will be a little more involved if you have to accommodate a second power supply in the whole thing. IOW, you can't just connect an 8" drive like you would a 5 1/4. You have to first find or build a 24 volt source. I am quite capable of doing this, but you can't compare that to just plugging in a 5 1/4.
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12-to-24V DC-DC converters of the required amperage are easy to find and compact. Google for "12V 24v DC-DC converter" and you'll get a mess of them--both DIY and commercial. You really don't need a lot of physical space for one. Most 8" drives require less than 2A at 24v.

Since you don't need an isolated converter, a simple boost regulator will work fine--and typically at better than 90% efficiency. Here's one such circuit for a 3A 24V boost converter from Maxim:

DI118Fig02.gif
 
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Shadow Lord said:
Chuck,

I don't doubt that Mike is right. However, to some of us w/ a bit of less EE training then the rest those wrinkles could be quite cumbersome!
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Well, as with most things these days there are several good articles on the web describing how to interface an 8" drive to a PC; I think Chuck and I just wanted to point out that it's not the big deal that some people think it is if you actually wanted to hook one up.
 
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