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The Personal Jukebox (also known as ''PJB-100'' or ''Music Compressor'') was the first consumer
hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with mag ...
-based
digital audio player A portable media player (PMP) (also including the related digital audio player (DAP)) is a portable consumer electronics device capable of storing and playing digital media such as audio, images, and video files. The data is typically stored o ...
. Introduced in 1999, it preceded the
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...
iPod The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes wa ...
,
SanDisk Sansa SanDisk has produced a number of flash memory-based digital audio and portable media players since 2005. The current range of products bear the SanDisk Clip name, a line of ultraportable digital audio players. SanDisk players were formerly market ...
, and other similar players. It was designed and developed by
Compaq Compaq Computer Corporation (sometimes abbreviated to CQ prior to a 2007 rebranding) was an American information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced ...
Research ( SRC and PAAD groups) starting in May 1998. Compaq did not release the player themselves, but licensed the design to HanGo Electronics Co., Ltd. of
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
. Compaq Research published a
software development kit A software development kit (SDK) is a collection of software development tools in one installable package. They facilitate the creation of applications by having a compiler, debugger and sometimes a software framework. They are normally specific ...
for the unit, which enabled users to develop tools, drivers and applications for different operating systems.


History


Development

The PJB was created as a personal audio appliance prototype by
DEC Systems Research Center The Systems Research Center (SRC) was a research laboratory created by Digital Equipment Corporation (DEC) in 1984, in Palo Alto, California. DEC SRC was founded by a group of computer scientists, led by Robert Taylor, who left the Computer ...
and Palo Alto Advanced Development group (PAAD). The project started in May 1998, a month before the
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president un ...
merger into Compaq was completed, and a final product was brought to market in November 1999. The PJB was the first hard-disk-based MP3 player made available on the market. The "100" in the "PJB-100" name was chosen from the capacity of the original 4.86 GB hard drive in the first Personal Jukebox. With this drive, the unit was expected to hold about 100 popular (45 minute) music CDs encoded at 128 kbit/s. The name was kept for the later models with bigger hard drives, even though these could store a larger number of albums. The PJB-100 was the first MP3 portable to garner a "Milestone" product designation from
MP3 Newswire Founded in 1998, the same year as MP3.com, MP3 Newswire is the oldest active news site devoted to digital media technology. Notable for its series of essays that chronicled the rise of digital music and the Internet’s acrimonious relationship wit ...
, which they defined in their January 2000 review of the PJB-100 as "any product whose breakthrough innovations are so significant, they influence the future course of its industry".


Licensing, marketing and distribution

Instead of manufacturing the player themselves, Compaq licensed the design to HanGo, which called it the ''"Personal Jukebox - PJB-100"''. The license from Compaq to HanGo was worldwide exclusive - nobody else could license the technology from Compaq during the term of the HanGo license. HanGo granted a distribution agreement to US company Hy-Tek Manufacturing of Sugar Grove, IL in 2001. HanGo rebranded the units sold through Hy-Tek as the ''"Compressor"''. HanGo took the PJB-100 into mass production and introduced it to the public at the Las Vegas COMDEX in November 1999. The first units were sold in a special auction held by MP3.com, with bids exceeding US$1000. Some winners received their players before the end of 1999. The first auctioned units were hand-built by the Compaq engineers who designed it, and had single-digit serial numbers.


Specifications

* Measurements: 150×80×26 mm (5.9×3.15×1.0 inches) (W×H×D) * Weight: 280 g (9.9
ounce The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman unit of measurement. The avoirdupois ounce (exactly ) is avoirdupois pound; this is the United States customa ...
s), 304g (10.7 ounces) including battery * Playback: MPEG-1 Audio Layer 3 (
MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Origin ...
) at
bitrate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...
s of 8 to 320 kbit/s and a sample rate of 44.1 kHz (playback support for WAV is in the
firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
, but is not enabled - it was used by the developers before the MP3 decoder was licensed from Fraunhofer IIS). * Audio
signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in de ...
(S/N): >90 dB * Audio
total harmonic distortion The total harmonic distortion (THD or THDi) is a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Distortion fact ...
(THD): <0.1% * Frequency response: 20 Hz to 20 kHz * Audio output power: >50  mW at 32
ohm Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm. Ohm or OHM may also refer to: People * Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm'' * Germán Ohm (born 1936), Mexican boxer * Jörg Ohm (bor ...
impedance


Hardware


Digital signal processor (DSP)

The heart of the PJB is its Digital Signal Processor. It controls the hard-drive, buttons, LCD, USB interface and handles MP3-decoding for playback. The PJB uses a 24 bit
Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...
56309 DSP running at 33 MHz. The MP3
codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...
(which is about 2 MB in assembly DSP code) was licensed from Thomson and
Fraunhofer IIS The Fraunhofer Society (german: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., lit=Fraunhofer Society for the Advancement of Applied Research) is a German research organization with 76institutes spread throughout Germany ...
.


Memory

The PJB has 12 MB of
DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxid ...
and 1 MB of
flash memory Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use ...
. The DRAM is used to buffer data (between 8 and 12 minutes of music, depending on the bitrate used for encoding) from the hard disk during playback. The buffer allows the disk to be run only intermittently, preserving battery life. When the hard-disk is stopped, battery life is preserved; the ramp-loaded heads also retract from the disk surface, helping to reduce the possibility of damage. The flash memory houses the firmware as well as the bootstrap.


Communication interface

To transfer data, the PJB is equipped with a USB 1.1 Type B connector. Inside is a Philips PDIUSBD12 USB peripheral controller, which averages a raw throughput of about 400 kB/s. Early prototypes used
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
instead of USB for data transmission. USB was used in production models because it was more common than Ethernet on standard home computers in 1998.


Display

The PJB's LCD has a resolution of 128×64
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...
s (2:1
ratio In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
) at a diameter of 3 inches (76.2 mm). Later versions of the PJB also featured a
backlit A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination ( ambient light or a ...
display (the backlight comes on when the unit is powered on, or a button is pressed and turns off automatically after a few seconds). The character set the PJB uses internally is Latin-1 (
ISO-8859-1 ISO/IEC 8859-1:1998, ''Information technology — 8-bit single-byte coded graphic character sets — Part 1: Latin alphabet No. 1'', is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in ...
), with some minor variations. One of the Compaq developers stated that "it's missing some of the symbols in the range 160 to 255 (because I got bored when I was creating them :-). Upper case accented characters are rendered unaccented, because that looks better within the font's 9 pixel height. There are some glyphs in the range 0 to 31, used for the symbols on the screen.


Hard drive

While flash players could store between 32 and a maximum of 128 MB at the time, the first PJB could store 4.86 GB of music. While the PJB-100 was updated as bigger drives became available, it was also possible for end users to replace the hard drive (although voiding the warranty in that case).


Buttons/controls

The PJB has 6 buttons on the front: * Left/Previous/Rewind * Right/Next/Forward * Up * Down * Play/Pause * Stop/Power off Volume is adjusted by a wheel on the unit's right side, using a
digital Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals ** Digital camera, which captures and stores digital ...
mechanism (it can be turned indefinitely). It also is possible to click or push the wheel, which pauses playback and turns the unit off after about one minute. When the unit is powered off and the wheel is pressed for a few seconds, playback resumes. This also works when the buttons are locked, in case the main controls cannot be easily accessed. On the same side is also a small switch which locks the unit’s controls (except for the wheel).


Battery and power supply

The PJB is not powered by dry cell batteries like most other players at the time of its development, but by a provided HanGo
Lithium ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also see ...
. HanGo sold a more powerful 1600 mA battery to be used in the PJB. The PJB includes a 5V
power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As ...
which charges the battery and enables playback without a battery in the unit at all. The charging control circuit for the battery is built into the PJB itself, not the power supply, so the use of a replacement power supply requires only the proper voltage and sufficient current capacity.


Accessories


Included accessories

Compared to other players, the PJB included accessories. Details varied from distributor to distributor, but UHU/Portacomp AG included: * Koss Porta Pro headphones * Leather case with belt clip * 5 V power supply with converters for European and American power outlets (except UK) * 1350 mW/3.6 V Li-Ion battery (see the battery section) * USB 1.1 compliant A-B connector cable * Cinch-Audio cable 3.5 mm to RCA * Manual (in German and English) * CD with drivers and Jukebox Manager software (Windows, Mac OS/OS X, Linux)


Optional accessories

Accessories were offered by distributors (among them headphones and speakers, also for use with other audio hardware than the PJB and replacements for the included accessories): * 1600 mAh Li-Ion Battery * Waterproof
neoprene Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion R ...
bag for use of the PJB at a beach or pool * Audio-cassette adapter for playback on car/home stereos * Swan-neck car-holder * Magnetic mounts to attach the PJB within a car * Power-supply-adapters for car cigarette-lighters


Firmware


Features and version history

The latest firmware version, which surfaced in December 2003, is v2.3.3-alpha; the latest stable version is v2.3.2, introduced in mid-2001. Initially, the functions provided by the player were basic: when music was played back, selecting another track would immediately start this track and stop the current one; playlists had to be created on the computer; files could only be uploaded to the PJB, but not downloaded back to the computer. New firmware versions came out regularly, but were mostly bug fixes with very few new functions introduced. Later firmware versions added some of the most requested features: * Files could be transferred from player to PC * The ability to browse without interrupting playback * Some (hidden) games were added


File system and table of contents (TOC)

The PJB's disk is not formatted as FAT or
FAT32 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons b ...
as is the case with most of the players that were released later, and enables those to be mounted as another drive in an operating system. Instead, a unique file system is used, which, while losing the mounting ability, is optimized for the structure of MP3 files (having a cluster size of 128 kB, which equals about 8 seconds of 128-kBit-encoded MP3-music). Therefore, managing actions like defragging become unnecessary. The file system allows the linking of Tracks into various Discs/Sets. Therefore, each track is ideally only stored once on the disc and recurring occurrences of it (for example in playlists or samplers) are just links to the original file. This may help to preserve a good amount of disk space and allows for more tracks to be stored on the disk. All of this info is stored in the TOC (table of contents). The TOC is stored in a human-readable text-format and can be downloaded, changed with a text editor and re-uploaded to the PJB again. A copy of the TOC is always stored on the unit as well, so errors and damage to the original TOC can usually be fixed.


Software


Software development kit

The original developers at Compaq Research designed an SDK (Software Development Kit) for the unit and published it under the
Open Source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized so ...
GPL license in 2000.


Drivers

The PJB does not integrate itself as a USB
mass storage In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. In general, the term is used as large in relation to contemporaneous hard disk drives, but it has been used large in relati ...
device into modern operating systems. Special drivers are required to make the operating system recognize an attached PJB. Drivers for
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...
and
Mac OS Two major famlies of Mac operating systems were developed by Apple Inc. In 1984, Apple debuted the operating system that is now known as the "Classic" Mac OS with its release of the original Macintosh System Software. The system, rebranded "M ...
were included, while drivers for
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...
were developed by the open source community.


Jukebox Manager (Windows, Mac OS)

The included management tool for the PJB is the Jukebox Manager (the latest Windows version is v1.5.6). It can create/delete/manage Sets, Discs and Tracks (when uploading, the user can choose which ID3-tag will represent which level). It can also encode CDs directly onto the PJB and query the
CDDB CDDB, short for Compact Disc Database, is a database for software applications to look up audio CD (compact disc) information over the Internet. This is performed by a client which calculates a (nearly) unique disc ID and then queries the databas ...
for the proper disc/track information. Finally it can update the firmware. If manipulating some values in the
Windows Registry The Windows Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the registry. The kernel, device drivers, services, Security Accounts Manager, and ...
, a hidden menu appears, which can be used to debug and in some cases repair a damaged TOC. The Jukebox Manager does not make use of some of the firmware’s later features, such as downloading tracks back to the computer and does not provide advanced features such as mass-uploading, synchronizing or creating playlists from M3U-playlists.


Linux projects

There are Linux projects operating on SourceForge (some under the banner of the OpenPJB project). These range from Jukebox-Manager-like applications with a GUI for various
window manager A window manager is system software that controls the placement and appearance of windows within a windowing system in a graphical user interface. Most window managers are designed to help provide a desktop environment. They work in conjunctio ...
s to projects making the PJB's file system mountable as a drive in Linux. Some of the projects include: * Jukebox Manager (KDE) * GNOME/GTK+ GUI Personal Jukebox Manager (GNOME) * Emacs PJB Manager * PJB File System for Linux (Kernel 2.3/4, 2.6) * PJB VFS module (for use with Nautilus) * pjmirror (written in Perl to synchronize the PJB with data on the PC)


External links


The new and improved PJB-100 User Group at Yahoo! Groups


*


Ultimate PJB-100 FAQ

Motherboard modification instructions

pjbExploder
(Windows) project home page
OpenPJB Project
Multi-platform command line tools and SDK
Jukebox Manager
(Linux/KDE) project home page
pjbmanager
(Linux/GNOME) project home page
Microsoft Windows 2000 drivers and instructions
(download from PJB-100 Yahoo! group, registration necessary)
Microsoft Windows XP drivers and instructions
(download from PJB-100 Yahoo! group, registration necessary)
Recent Linux 2.6 kernel drivers
(download from PJB-100 Yahoo! group, registration necessary)
File System info
- The PJB's file system and other technical info for developers (PDF) * - Patent covering one of the key technologies of the PJB: Buffering data into RAM and playing it back from there * {{US patent, 6377530 - Patent covering an aspect of buffering data in RAM Digital audio players Audiovisual introductions in 1999 Jukebox-style media players