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The Last Moving Part

Computing · c. 2007

About

The Last Moving Part

Preparing exhibit…

Operate

WRITE A FILE

Records

ROOT DIRECTORY

name	size	frags

no files — disk freshly formatted

Format erases the directory and allocation table of this model disk. It cannot be undone.

DRIVE OPERATION

operation—LBA—cyl / head / sector—seek—rotational latency—transfer—spindle RPM—capacity used—

OPERATION LOG — completed disk operations

	operation	LBA extents	drive time

no completed operations yet

ALLOCATION TABLE (FAT) — one cell per cluster

freefile dataFAT + directory

READ-HEAD SIGNAL — a pulse at every flux transition

PREAMBLESYNCDATA 512 BECC

FIRST SECTOR (hex) — format signature shown in bold

platter slowed ~200× · bit cells enlarged ~10,000,000×

.museum-body--immersive { overflow: auto !important; } .museum-main--fill, .museum-runtime { height: auto !important; min-height: 100vh; overflow: visible !important; } .museum-runtime > .exhibit-root, .museum-runtime > :not(#mw-about):not(noscript):not(script) { display: none !important; } .museum-runtime #mw-about { display: block !important; position: static; width: min(100%, 800px); margin: 24px auto; padding: 24px; box-sizing: border-box; } .museum-runtime [data-about-close], .museum-runtime #mw-about > h2 { display: none !important; }

c. 2007 · Computing

The Last Moving Part

Two spinning platters, a voice-coil arm, and a modeled FAT workflow — follow files from clusters to a magnetic-bit visualization.

This exhibit represents a 3.5-inch, 7200 RPM SATA hard disk drive with two modeled platters, a voice-coil actuator, parking ramp, spindle motor, and controller board. Dimensions, track count, bit-cell scale, seek timing, and component details are selected for an inspectable teaching model rather than copied from one production drive.

A small FAT-style file-system model assigns clusters, updates a root directory and allocation table, and schedules head motion using computed seek and rotational-latency terms. The magnetic surface view maps the demonstration bytes to enlarged bit polarities. File signatures and data structures support the lesson, but the browser is not writing a physical disk or emulating a complete SATA drive.

The guided sequence shows allocation, deletion, cluster reuse, fragmentation, and an additional seek between extents. When this model deletes a file, metadata changes while its data clusters remain unchanged until reused; recoverability on an actual system depends on later writes, file-system behavior, drive firmware, and storage technology.

Specifications

Form factor: 3.5″ SATA desktop drive, two platters, four heads
Spindle: 7200 RPM in-hub BLDC, 9-slot stator, fluid bearing
Recording: Perpendicular, zoned bit recording, 16 cylinders (exhibit scale)
Simulated: FAT file system, seek + rotational-latency math, magnetic bits

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