Comparison of several forms of disk storage showing tracks not-to-scale ; green denotes start and red denotes end. A CD-ROM drive without case The rotational mechanism in an optical drive differs considerably from that of a hard disk drive's, in that the latter keeps a constant angular velocity CAVin other words a constant number of revolutions per minute RPM. With CAV, a higher throughput is generally achievable at the outer disc compared to the inner. It was a feature important for streaming audio data that always tend to require a constant bit rate.
Xerox Alto restoration, IC reverse engineering, chargers, and whatever Macbook charger teardown: The surprising complexity inside Apple's power adapter Have you ever wondered what's inside your Macbook's charger? There's a lot more circuitry crammed into the compact power adapter than you'd expect, including a microprocessor.
This charger teardown looks at the numerous components in the charger and explains how they work together to power your laptop. Inside the Macbook charger. Many electronic components work together to provide smooth power to your laptop.
Most consumer electronics, from your cell phone to your television, use a switching power supply to write amplification ibm laptop AC power from the wall to the low-voltage DC used by electronic circuits.
The switching power supply gets its name because it switches power on and off thousands of times a second, which turns out to be a very efficient way to do this conversion. In the s, switching power supplies were complex and expensive, used in aerospace and satellite applications that needed small, lightweight power supplies.
By the early s, new high-voltage transistors and other technology improvements made switching power supplies much cheaper and they became widely used in computers.
Apple's involvement with switching power supplies goes back to when Apple's chief engineer Rod Holt designed a switching power supply for the Apple II. According to Steve Jobs: Rod doesn't get a lot of credit for this in the history books but he should. Every computer now uses switching power supplies, and they all rip off Rod Holt's design.
The switching power supply revolution happened before Apple came along, Apple's design was similar to earlier power supplies  and other computers don't use Rod Holt's design.
Nevertheless, Apple has extensively used switching power supplies and pushes the limits of charger design with their compact, stylish and advanced chargers. Inside the charger For the teardown I started with a Macbook 85W power supply, model A, which is small enough to hold in your palm.
The picture below shows several features that can help distinguish the charger from counterfeits: Apple 85W Macbook charger Strange as it seems, the best technique I've found for opening a charger is to pound on a wood chisel all around the seam to crack it open.
With the case opened, the metal heat sinks of the charger are visible. The heat sinks help cool the high-power semiconductors inside the charger. Inside the Apple 85W Macbook charger The other side of the charger shows the circuit board, with the power output at the bottom.
Some of the tiny components are visible, but most of the circuitry is covered by the metal heat sink, held in place by yellow insulating tape. The circuit board inside the Apple 85W Macbook charger.
At the right, screws firmly attach components to the heat sinks. After removing the metal heat sinks, the components of the charger are visible.
These metal pieces give the charger a substantial heft, more than you'd expect from a small unit. Exploded view of the Apple 85W charger, showing the extensive metal heat sinks. The diagram below labels the main components of the charger.IBM claimed the disparity is the end result of its custom design that offers more flash capacity for fewer dollars than its competitors.
It is clear that the future of flash-based technology will feature even more customized and optimized designs. It Turns Out Gutenberg Isn’t Actually Impressive Blue Box.
To prepare to write this blue box, I found this video explaining how Gutenberg’s press worked and was surprised to find myself unimpressed. I always assumed Gutenberg had made some genius machine, but it turns out he just created a bunch of stamps of letters and punctuation and manually arranged them as the page of a book and then.
Write amplification (WA) is an undesirable phenomenon associated with flash memory and solid-state drives (SSDs) where the actual amount of information physically written to the storage media is a multiple of the logical amount intended to be written.
View and Download Toshiba Satellite P user manual online. Satellite P Laptop pdf manual download. Also for: Satellite p, Qosmio x, Qosmio g60, Satellite pd, Satellite pd, Satellite p, Satellite pd. Started in by the Dark Tangent, DEFCON is the world's longest running and largest underground hacking conference.
Hackers, corporate IT professionals, and three letter government agencies all converge on Las Vegas every summer to absorb cutting edge hacking research from the most brilliant minds in the world and test their skills in contests of hacking might.
IBM research teams focus on understanding the technology and characterizing how the technology reacts to different workloads and data patterns. Using that characterization, development teams drive changes to the controller design while mitigating the effects of retention, endurance, and the complexities of erase, programming, and read effects in .