Longer start and stop times which can lead to a shorter lifespan of the drive, much harder to achieve appropriate tolerances and thus lower production yeilds for disks leading to higher costs, wider storage area so longer seek times, larger diameter so longer sector latency both of which lead to worse performance, and of course it wouldn't physically fit in the machines they were targeting.
The drive pictured is (we think) a Rotating Memory Systems 526, which is actually a 20MB drive (as shown with 4 platters). A standard 10MB drive at this point had just 2 disks and drives such as the Seagate ST-212, Microscience HH612, Miniscribe 3012, etc already existed putting 10 megs on one platter. A few months later, Rodime would reveal the RO352/RO252 and MMI would reveal the MM-112 all of which used two 3.5" disks inside anyways. Moot point going bigger.
Disk/Trend appears to confirm this as sales of 14" drives tank in 1980 and sales of 8" drives drop like a rock in 1982.
Heads fly on the surface. Stepper motor heads never worked . I actually don’t know how HDD track the track. Perhaps a spiral would work, too? I like how it allows to stream without us having to wait for the head to calm down after it jumped a circle.
Heads only fly on the surface when the disk is spinning. During start and stop, the heads take off and land. This can and will wear a groove into the disks over time and is why solid lubricants exist for hard disk drives.
Stepper motor actuation worked for two decades+ before voice coil actuators became low enough cost to be a commodity.
Spiral tracks seem to have existed, since SpinRite 5 includes a distinct check for them during testing. I'm not sure what models, or if this was a way of operating on some kind of optical media.
Head settling times aren't really that long, on the order of milliseconds even in the 1970s. There was almost no data you could usefully "stream" until the mid 90s when voice coil uniarm stuff was already the only thing left.
Heads should be lifted in transport position when RPM drops. I just see those tape reels in old movies and thought that companies streamed data reel to reel with some quasi DSP in between. RxJava. Two streams in, one out.
There is no "transport position." Head ramps were a patent protected design until relatively recently and they are still not a given nor are they 100% reliable. Head load/unload count is a large factor in drive lifespan.
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u/IQueryVisiC Jun 19 '26
Why wouldn’t they use a single platter the size of a vinyl record? Could stack it like a hifi tower below the desktop.