Understanding CD-R and CD-RW (2003) [pdf]

101 points2
sn_master8 hours ago

A year or so ago I made a post on reddit/TIL that referenced CD-R and it got deleted by a mod because "CD-R is not a known thing" or something like that. The mod must've been too young to ever used a CD-R. That was kind of shocking to me, but then I haven't used CD-R myself in almost a decade.

Scoundreller8 hours ago

A few years ago I mentioned a certain configuration needing a cross-over cable. Never heard of Auto MDI-X... I guess one can get through life using cross-over cables and straight cables where they used to be required, but you're going to cause confusion if you ask for a x-over cable at a shop.

Dalewyn7 hours ago

That is so perfectly Reddit.

IYasha1 hour ago

I've written a DVD a week ago :)

Also, CD-Rs are used a lot in legal world, DVDs in medical equipment. BDs in studios and for data backup.

gymbeaux4 hours ago

There are reasons we are here and not on Reddit

IYasha39 minutes ago

There's at least one good reason: one of the major investors in Reddit is Tencent.

flangola72 hours ago

Reddit is (mostly) just bigger. There are parts that are worse but there are also parts that are much better.

SillyUsername1 hour ago

Reddit used to be like Hacker News, but as it became popular the memes started rolling in, and effectively lowered the IQ quotient and technology bias of the home page content and diluted the sub reddits.

I looked back through a few years ago to anecdotally prove this theory to myself and yes, on the front page the factual content (in my personal opinion) as opposed to meme content seems to drop between 20-40% compared to more recently.

The same seemed to happened to which made people move to reddit (remember that before it killed its user base?). I really hope this never happens to Hacker News...

dijit56 minutes ago

This comment reeks of exceptionalism and “iamverysmart”. I hope you dont take strong offence to that because I am not saying you think this way, only that what you wrote sounds that way.

That said: Mass appeal always lowers the quality of discourse, due (in part) to there being more of a bias towards being first (the first comment to make a certain type of joke will be rewarded most) and also due to the fact that people tend to aggregate around things that are fun, not necessarily correct.

btw: IQ is a measure of pattern matching and is used in children to determine mental development relative to their biological age, it shouldn’t have any affect on internet discourse.

fortran773 hours ago

For insightful comments like yours!?

I’m on both.

nu11ptr8 hours ago

I still recall very well how frustrating "buffer under-runs" a day and an age when we really need a real-time OS, but we simply weren't running them.

I can't decide if I love this doc or if it gives me post traumatic stress. This is another subject I haven't thought about in years as it has faded out, but having dealt with all the different permutations of CD writable I had forgotten just how many different variations there actually were, and how long the industry kept trying to improve the tech.

ramraj078 hours ago

I mean it wasn’t the biggest issue in the world once you know the root causes? If I was writing a ton of stuff I made sure to create an iso first so there’s not much of random files being searched for. And also learn your machines limits and write at a conservative speed..

orev6 hours ago

It was highly dependent on when you were doing this. There was a time very early on where even moving the mouse would cause it to skip. (also had the same issue playing MP2 (yes, 2) audio files). That was when we were really pushing the limits of the hardware (33MHz 486).

These issues were resolved pretty quickly in the next generation of CPUs and recorders, so if you missed out on the very early versions you never would’ve seen this problem.

jwalton6 hours ago

Back when you needed a carrier to hold the CD-R on the drive.

mindslight6 hours ago

It was when you were using a defective Philips drive that underran regardless of the host, and blanks were $10 each.

(perhaps my first experience with class action lawsuits. a coupon for $200 off another $400 drive, thanks!)

cyberax3 hours ago

I remember one CD burner application basically monopolizing the OS by raising its priority to max, making everything else completely unusable.

And to make the wait a bit less painful, it had a game of tetris that you could play while the CD was being written.

sohkamyung10 hours ago

I used to work for a consumer electronics company that made CDROM drives. Fun times, staring at eye diagrams on oscilloscopes to make sure the hardware was working.

I remember one time an engineer was testing a 16x(?) CDROM drive, and the disc inside broke. That was a real mess. :-)

NovaDudely10 hours ago

16x doesn't seem like that much considering they routinely went up to 52x but I guess it is up to the quality of the discs being used.

If it was a 16x DVD drive then that would probably explain it.

Mostly unrelated.

Now a slight pet peeve of mine was an episode of Mythbusters where they tackled the issue of exploding discs. The issue was the Adam took the data transfer rate of 7.2MB/sec and then extrapolated this to the inner disc area and came up with 30,000 RPM. About 3 times faster than what the discs actually spin at. So naturally discs start blowing up every time they ran the experiment.

Adam assumed a constant linear when drives are actually constant angular. Drive spins, you get what ever data comes.

acomjean7 hours ago

I had a Kenwood truex 52x drive. Worked well. It basically used 7 lasers to read across the disk at a slower speed. It generally worked well.

lxgr8 hours ago

CDs are CLV, at least according to Wikipedia.

But that probably doesn‘t prevent drives from operating them as CAV, as long as they vary the read/write rate accordingly.

aidenn04 hours ago

CD-ROM drives over some speed (4 or 8x I think?) were all CAV and they used the equivalent CLV speed at the outside to get the bigger advertising number.

dumbotron6 hours ago

Fun trivia: hard drives write from the outside in because the performance is better due to (once) being constant CAV. People would sometime "short stroke" drives by using an undersized partition, improving both latency and throughput.

generalizations8 hours ago

Yeah, ever since hearing about the episode where they investigated whether harmonics can take down a building...and they strapped a jackhammer to a 10' I-beam...I've been taking their stuff with a massive grain of salt.

omoikane8 hours ago

I think Mythbusters is meant to encourage experiments. Any actual results is bonus.

hatsunearu9 hours ago

so it's 7.2MB/sec if your data is stored near the edge?

Or is data stored "closer together" when it's in the inner track?

aidenn04 hours ago

Yes, you've got it right; the data stored near the center is read at a slower rate (because there is less data on the innermost rings, but most drives spin at a constant speed when not playing CD audio).

userbinator8 hours ago

The format is CLV, but drives advertise their speed as the CAV rate at the outer edge where it's the highest, and all high-speed drives use physical CAV so the data rate changes, starting at the lowest at the inner part of the disc where the data begins, and increasing with increasing LBA up to the highest at the outer edge.

bityard8 hours ago

With the drive spinning at a particular constant RPM (which is what they do), then the data rate is the same no matter where you are reading the disc.

IndySun8 hours ago
dylan6048 hours ago

wow, i'm trying to imagine how loud a 30,000 RPM CD-ROM drive would be. Did the constant angular confusion seem genuine like he just didn't know or more along the lines of it was much more compelling programming to conveniently ignore the fact?

yarg10 hours ago
Tokkemon6 hours ago

But of course, Alec from Technology Connections has us covered:

initramfs2 hours ago

For the record, I was able to record a CD-R at 1x (the only speed I trust) on a 486 SX2 processor, running at 33MHZ in the late 90s/early 00s, just to test whether I really needed a 233MHz Pentium II PC as advertised on most Best Buy CD-writer boxes. The write completed in about 50 minutes. Never stop dreaming.

IYasha1 hour ago

I wish there was a more in-depth PDF for DVD and Blu-ray. I found it really hard to follow the decoding process from light to user data. :(

sohkamyung34 minutes ago

The specification for Audio CDs is the "Red Book". The Internet Archive has a copy [1]. There should be similar standards for DVD and Blu-ray, but they should be based and enhancements of the Red Book since they have to be backward compatible with Audio CDs.

For a slightly higher level look, try "Understanding and Servicing CD Players" by Ken Clements [2], which goes into some details on how CD players work to read data from CDs.



WirelessGigabit5 hours ago

I have never in my life seen a multi-volume disk.

I have always wondered though; on Windows you could write to a CD-R but not finalize it.

Could you delete the file? I'd test it as blank CDs are dirt cheap, but I don't have a writer...

irdc2 hours ago

> I have never in my life seen a multi-volume disk.

Some games (I personally only know of Total Annihilation from 1996) had both data and music (in the form of CD digital audio) on the same disc.

kevin_thibedeau2 hours ago

With ISO9660 CD-Rs you can delete files from the index of a new session. However the original session is unaltered and software that exposed them allows access of deleted files.

justsomehnguy10 hours ago

> What is Mount Rainier?

> The Mount Rainier specification was developed in 2001 to provide the framework necessary for computer operating systems to seamlessly rewrite data CD-RW discs in a drag and drop fashion without the use of additional drivers or software. Through enhancements over the abilities of conventional packet writing software, including background formatting, recorder-based defect management, improved interchangeability and greater ease of use, Mount Rainier’s goal is to make 3.5” floppy diskettes obsolete by replacing them with CD-RW discs for everyday data storage and interchange.

Guess it never caught on? I knew about UDF but not so sure about M.R.

> Do some CD-R recording speeds produce better results than others?

> Recorder and media manufacturers carefully tune their products to operate with each other across a wide range of speeds. As a result, equally high quality CDs are created when recording at almost all speeds. However, 1x presents a minor exception. Generally speaking, the physics and chemistry involved in the CD recording process seem to produce more consistent and readable marks in CD-R discs at 2x and greater speeds.


TylerE10 hours ago

It never did because USB keys became cheap and ubiquitous (and larger!) right around the same time.

ClumsyPilot8 hours ago

USB keys have a big problem of being writeable. Sometimes you want something that is written once, and once only, and you know it has not been altered.

CD's lend themselves to archiving the way paper does. You lend someone a USB, you don't know what they are returning on it to you.

abofh3 hours ago

Maybe, but I seem to recall most CDR/RW only had a shelf life approaching double digit years. The rest of your point certainly stands though

kevin_thibedeau2 hours ago

M-disc CD and DVD media is good for much longer.

bityard8 hours ago

No, it never caught on because CD-RW drives came on the market soon after and were more or less the same experience without the drawback of "using up" the disc.

Cheap 512MB and 1GB USB flash drives came much, much, later.

kodt7 hours ago

Exactly, little 32 - 128 MB flash drives were around not too much later and removed the need for floppy discs for saving documents and such. But for larger sizes CD-RW was more common.

There were also Zip and Jazz drives but they weren’t as common due to cost.

charlieyu18 hours ago

DVD was the one that obsoleted CD based storage.

justsomehnguy9 hours ago

Thanks, I was there million years ag^W^W^W.

I've seen a couple of times when people used drag-n-drop for the batch writing, but that was because they were totally clueless about how you should write data on compact disks. *grin*

> became cheap and ubiquitous


> and larger!

No. Refer to [0] for a remainder on how large and fast they were. And that is 2005. Sure, by 2008 anyone who wanted or needed could had a 8/16GB one, but between 2001 of the spec, 2003 of the doc and 2008 there are 5-7 years.

NB I worked as L1+ tech at that time and I had a CD-R with Ghost'ed WinXP, specifically so I could install it on an ancient PCs without a DVD drive. By 2008 my tools were on a bootable thumbdrive and I no longer took a 30+ CD case with me on a regular basis.


I also like what they tested bundled software and reported how much memory those program use in the RAM.

TylerE8 hours ago

512MB is larger. I spent my college years (circa 2000) toting a 32mb drive around.

justsomehnguy5 hours ago

> 512MB is larger

I'm talking about CDs. And my memory isn't that bad (yet) to forgot 620/650/700MB capacity.

bastawhiz9 hours ago

The other commenter is also right, but CD-RW also had two fatal flaws:

1. It was notoriously unreliable. Data would fail to write and corrupt the disk. Disks would often fail after a few uses.

2. It was horribly slow, both to read and write (in my experience). In many cases it was faster to burn a CD-R with lots of files instead of moving individual files to a CD-RW.

Maybe it was just my computer at the time, but CD-RW was more of a novelty than anything. It could have been good, but it simply just didn't do what it said on the tin.

bombcar8 hours ago

I remember having a burning program that would let you “append” to a CD-R somehow, which took care of 80% of what I would have needed cd-rw for anyway.

Scoundreller8 hours ago

I think that was DirectCD. Nice thing about it is that you'd never get buffer underruns for some reason. Can't use it for cd audio of course, but yes for mp3s!

xen2xen16 hours ago

DirectCD, that's a name I'd nit heard in many years...

wkat42426 hours ago

Multi-session the tech was called. Though marketed by vendors under different names.

andrewmackrodt6 hours ago

Windows XP also supported this natively, i.e. track at once rather than disc at once behaviour.

Multicomp8 hours ago

I still use the Mount Ranier style UDF drag n drop on disks since they are write once read many and therefore good offline storage for resisting ransomware.

I wish I could do packet writing on Linux but I think the packages n such that it would enable that have rotted away over the years. Or at least I wasn't able to find them when I went looking for them.

simoncion7 hours ago

This is in the Gentoo Portage tree, so I'd expect it to work:

    * sys-fs/udftools
         Available versions:  2.3
         Description:         Ben Fennema's tools for packet writing and the UDF filesystem
tpmx10 hours ago

Raw CD-R and CR-RW's are actually still widely available for purchase. I wonder for how long though. Especially for CD-R that's an impressively long run of almost/about 30 years.

Bought a bunch of CD-R's recently to burn some retro apps/games to get that proper feeling (sound, latency).

NovaDudely10 hours ago

I still have a spindle of them kicking around mostly for legacy OS stuff like old PowerPC Mac installations. Some version of Open Firmware just do not play nice with USB's.

The issue I have is think a lot of the discs I get are hyper aged and it is a flip of a coin if they actually work or not.

tpmx9 hours ago

Buy some fresh ones while you can.

NikolaNovak9 hours ago

I hope for a while yet. My car has a 6 cd changer :-D

kristopolous8 hours ago

There's car stereos for literally under $15 shipped these days. I'm not exactly recommending those models, but car stereos are generally quite affordable and easy to install. Something to consider

Scoundreller8 hours ago

They're usually garbage at that price point. The thing about a CD-changer though is that it usually guarantees that your existing system has a line-in for other devices.

But sometimes the integration requires you to have a donor audio CD constantly playing even though you've spliced into the audio feed.

adanto68408 hours ago

Do many cars still have a single height "head-unit" space available in them these days? My wife's 2017 Hyundai doesn't. The last car I had that could accommodate a 3rd party head-unit install was a 2004 Subaru, and it required buying manuf. replacement bevel for where the OEM clock went IIRC. Maybe latest car stereos are just entirely headless?

smackeyacky8 hours ago

Companies like scosche make plastics to adapt some cars, most popular older cars with cd players or changers would be able to be upgraded to a mechless head unit without too much hassle.

u801e5 hours ago

They're still available, but I prefer getting writable discs with higher capacity, like DVD-R or BD-R. I still use my DVD-R as one of my offline backup methods (make an ISO, put a bunch of files and a sha256sum file on the disc).

brudgers9 hours ago

As best I can tell from my recent interest, Verbatim is the only CD-RW name brand in the US market. [0] It may be the old Mitsubishi formulation and reliable. But the brand has changed hands over the years.

CD-R’s are more widely available.

[0] I acquired a Roland device from 2001 that is particular about CD-RW’s. No name disc’s don’t work in it but they format fine with a new external DVD burner…hence the rabbit hole that led to this submission.

dumbotron6 hours ago

Weren't CD+RWs considered the better format? Maybe this is just my experience with a first-gen xbox that makes me think this.

gitfan8610 hours ago

That is amazing since thumb drives are much cheaper by the MB and less prone to degredation

NikolaNovak9 hours ago

>>less prone to degredation

Are they, over time? I always assumed thumb drives would rot after years let alone decades.

pdntspa6 hours ago

I have CD-Rs that I burned 20 years ago that are still readable. I would say this is the majority of disks.

I have a box of thumb drives that are between 10 and 20 years old... less than half of them even register, let alone read anything. And often those that do quickly die.

orangepurple6 hours ago

Not only that but if you budget for an expected error rate of let's say 10% you can use par2 to create additional files that add that redundancy to your archives. par2 default redundancy is set to 5%. PAR2 uses Reed-Solomon Coding to perform its calculations.

tpmx9 hours ago

I'm guessing this product line is kept alive by outdated local government/municipality regulations or something along the lines of that. Oh, and owners of cars with CD players :).

About now is probably the time to hoard.

ClumsyPilot8 hours ago

I needed my x-ray form the hospital, they gave me a CD. It actually kind of makes sence - they aren't gonna keep stacks of USB drives,.

userbinator8 hours ago
jeron9 hours ago

Soon we will be able to recreate the entire feeling in VR, sound and latency included

nigrioid7 hours ago

I want 10TB optical media that costs $5 each.

tombert4 hours ago

It’s not optical, and it’s not “fast” in any traditional sense of the word, but LTO tapes can kind of approach what you’re suggesting. I’ve seen LTO-7 tapes sell for as low as $10 on eBay sometimes, and they advertise that you can get upwards of 15TB of storage if you enable compression.

Granted, while the tapes are comparatively cheap, the tape drives very much are not…

kevin_thibedeau2 hours ago

Trick is to stick to older LTO drives with U160 SCSI. Nobody wants them.

dumbotron6 hours ago

Honestly, I'd pay $50, maybe $100 for that.

orangepurple6 hours ago

That would be something like LaserDisc with BluRay media LOL

aidenn04 hours ago

Or BDXL with 320 layers...

justsomehnguy9 hours ago

BTW a previous discussion on 'Longevity of Recordable CDs, DVDs and Blu-Rays (2020)'

nailer7 hours ago

I did my work experience (internship) at ‘computers click here’, for a week. I was 15 and super excited to work in a PC store. They had pentiums and command and conquer.

The staff liked me and asked me to work a couple of extra days on the weekend for a big computer expo (maybe PCIT) so I became a fifteen year old salesperson, selling games and powerpoint 97 (rest of office wasn’t out yet). Rather than being paid in cash, we negotiated something better: a CD ROM! I think it was 8x.

The sad part of the story is that after they gave me the CD ROM for working the weekend my Mum got a call from someone saying I stole it. Maybe someone didn’t have permission to give me it? I didn’t have to give it back in the end - i guess the manager spoke to the right person - but the false accusation still really hurts. It would have been a really happy story otherwise.