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Geek Trivia: A sound argument

Why did the original technical specification for the compact disc, agreed on by both Sony and Philips, set the diameter of the CD at 120 millimeters -- a somewhat controversial decision with some infamously unusual reasoning behind it?

When you say the words "red book," the average (non-engineer) person probably assumes you're referring either to Redbook magazine or the so-called Little Red Book, the nickname of the pocket version of Quotations From Chairman Mao Tse-Tung. However, audio technicians and audiophiles know the Red Book as shorthand for IEC 60908, the International Electrotechnical Commission's official specification for the compact disc.

The complete spec is proprietary and requires purchasing a license from Philips for a fee -- between $200 and $5,000, depending on the format of the spec you're looking for. But most of the basics spelled out in the document are common knowledge and shaped the modern CD as we know it. They include:

  • A maximum playing time of 74 minutes, including pauses
  • A maximum of 99 tracks per CD
  • A disc diameter of 120 millimeters (mm)
  • A disc thickness of 1.2 mm
  • A center spindle hole diameter of 15 mm

This, of course, is just the tip of the techno-jargon iceberg, omitting such classics as non-return-to-zero, inverted binary; cross-interleaved Reed-Solomon encoding; and eight-to-fourteen modulation. Nonetheless, IEC 60908 has dictated the shape, size, operation, and function of nearly all compact discs since Philips released it in 1980 -- two years before CDs ever hit the market.

Only recently have companies released CDs that don't comply with IEC 60908, and most of those violations are attributable to copy-protection schemes or dual-layer DVD/CD encoding. Suffice it to say, the vast majority of the 200 billion audio CDs sold since the compact disc's debut 25 years ago have conformed to the 60908 standard.

You'll note that we haven't mentioned Sony -- the company most often associated with the creation of the compact disc. That's because Philips and Sony co-developed the CD, with much of the technology derived from Philips' existing (though ultimately unsuccessful) LaserDisc video efforts. When the first compact disc rolled off the assembly line on Aug. 17, 1982, that line was at a Philips plant in Germany.

The two companies collectively developed and agreed on the specifications found in IEC 60908, but the basis for at least one of those specs -- the 120-mm diameter of the CD -- was somewhat controversial, especially when you hear the possible reasoning behind it.

WHY IS THE COMPACT DISC STANDARDIZED AT 120 MM WIDE?

Get the answer.

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Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

15 comments
virgil
virgil

Hello... I'm in the CD and DVD business and have been since 1994. I have run a significant optical media replication facility and have been privy to quite a bit of the behind the scenes stuff. So - I'm quibbling! [1] Duration The Red Book specification (Sony, Philips, et al), calls for "approximately 60 minutes" in the August 1995 edition of the "Compact Disc Digital Audio System Description" aka the Red Book, page 1, first item under "Main Parameters" (sitting here on my desk). CD-R at that time came in 600 Mb and a little later 74 minutes versions. Now, 80 is the defacto standard for CD-R. 80 minutes replicated media was a later product which was the result of various audio artists needing more space for their enormous works, such as DJ performances, etc. In the beginning, the reliable playback of long media like this was quite unpredictable. At the earliest stages of the CD, the reason for the shorter duration discs was threefold: [1] The reliability of pit replication from the stamper at the outer edge of the disc was less controllable and therefore playback was potentially risky. [2] The edge of the disc during metallisation (sputtering) could in some cases be insufficiently metallised or damage could occur from a too-hot outer mask, which frequently occurred in some earlier sputter stations (Balzers and others). This too was later controlled. If you look on some early discs, there is a 'burn' at the edge of the disc where this too-hot mask condition or poorly controlled sputter station condition is visible. [3] The specification for the servo mechanism for the playback devices called for 74 minutes. Not all players were created equal. Some could not accurately control the read laser's position to reproduce the programme material after about 65 minutes. We made an Audio CD for a client in about 1997 which exceeded that stable 74 minute threshold by only a couple of minutes. The result was that more than 30% of retail buyers couldn't play those last few minutes and the product was recalled, the content re-mastered and re-pressed, etc. [2] Size Sony's original intent was to use the smaller physical track size (track pitch, pit geometry, etc) on the LaserDisc format, allowing a large amount of music to be placed on the disc. However, the amount of programme material on the disc would have made the disc prohibitively expensive at retail. Philips reverted to Sony and showed them the smaller physical format (have forgotten the name of the instigating research scientist at Philips, Eindhoven)which was more convenient and better yet created a better economic model and greater chance for success (ref: ODME BV, Eindhoven & Veldhoven, NL; successor of a former Philips subsidiary). Sony was gobsmacked and thus the partnership was firmed up, essential patents owned by both organisations but administered by Philips, levying a USD$0.0x royalty per unit, as well as as initial licensing fee of USD$25000 for the Red Book and all other relevant books for the licence. HTH. Cheers!!

tundraroamer
tundraroamer

The 120mm size is more aerodynamically stable then the smaller 115mm. This is an important consideration when spinning disks at high RPM as in playing a wicked game of office Frisbee.

rdabkowski
rdabkowski

When "Red Book" was initially mentioned in Geek Trivia, this non-engineer immediately thought the discussion was going to be about the infamous Adobe "PostScript Language Reference Manual". The OTHER Red Book. The Postscript series are affectionately known by their cover colors: red, green, blue & white.

pkrouse
pkrouse

The first part of the post mentions a 78-minute playing time as part of the red book standard, and the last part mentions 74 minutes. Which one is it? Is there some weird way they can both be correct? Either way, some clarification would be good...

seanferd
seanferd

"Mythbusters" had to spin up a disk on an over-amped router to get it to shatter.

Desmodeus
Desmodeus

In Australia the "Red Book" is generally assumed to mean the listing of average sale prices of used cars. You look up the model of car you're after and the book gives the average sale price for that model of car over the previous year.

seanferd
seanferd

My first thought was Red Book Audio, then I assumed that he must have meant something different :)

dcharles
dcharles

...the original Apple II reference manual (letter size, perfect bound. Most copies of it are defective in my experience - one range of pages is duplicated and another missing).

Uncle Andy
Uncle Andy

And this system administrator immediately thought of the IBM Red Book series -- the documentation and how-to series that IBM has published for many years on its various hardware and software products.

brians
brians

I recall that the choices were always 74 minute and 80 minute. While 74 seems to be the official standard, I still see tons of 80 minute CDRs. That should be enough for Beethoven's 9th plus Stairway to Heaven.

ashepard
ashepard

IBM Red books "or how we did it after readint the documentation" are worth their weight in gold. In second Life IBM let people meet and thank those who documented their trip through installations or set ups. Ahh the AS-400, 4341 and 9370! Those where the days.

sjdorst
sjdorst

While I'm the IT Manager (actually the entire department), I'm also in sales, purchasing - You got it, I'm working for a VERY small business. MY Red Book is a product catalog-- In Lighting, the Lightolier catalog been called the Red Book for as long as I've been in the business.

faradhi
faradhi

I remember them from working on the AS400, now called iSeries, machines,

williaa6
williaa6

A 4341 running multiple DOS under VM. sigh.

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