Understanding CD-R and CD-RW (2003) [pdf] | Hacker News Reader

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

osta.org

109 pointsbrudgers110 comments

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.

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.

That is so perfectly Reddit.

There are reasons we are here and not on Reddit

For insightful comments like yours!?

I’m on both.

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

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 archive.org 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 digg.com which made people move to reddit (remember that before it killed its user base?). I really hope this never happens to Hacker News...

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.

This was not my intention or what I hoped to convey.

I don't hold a bias (I couldn't if I wanted to - I have a son with Down Syndrome) I just wanted to point out a reason for the change - which you more eloquently wrote - since I miss the more technical discourse.

Reddit is just like Facebook. If you are seeing low quality content, it’s mostly the fault of self selection.

On Reddit, the serious subreddits don’t have a lot of memes and many prevent them. On Facebook if your feed is full of toxicity and politics, it’s because your friends are FB warriors and toxic.

> effectively lowered the IQ quotient

Yeah, you really demonstrate how it's lowered. Intelligence quotient quotient

I'm not going to do you a personalised study. Why don't you check it for yourself instead of down voting, or perhaps actually prove me wrong - my comments clearly stated this is anecdotal and "effectively"?

If you take a small pool individuals who discuss technical topics, and dilute it with more people it will trend down owing to the population IQ approaching the average of ~100.

Technical articles will also be less prevalent owing to the relative greater number of non technical topics and less interest in those that are.

It's not that technical people don't enjoy memes, it's that the wider populous won't enjoy esoteric technical or scientific articles.

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

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.

DVDs are still available in many stores for movies, but there's nothing mainstream I can think of that still uses CD-Rs.

CD-Rs are used a lot to transfer data between air gapped or TRMPEST computers. It is quite easy to destruct a CD-R, and they can’t be reused. Hard to destruct a USB memory, and the possibility to reuse them always increases the risk that some one does that and leak confidential information.

I still recall very well how frustrating "buffer under-runs" were...in 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.

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..

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.

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

You had a CD writer on a 486 at 33 MHz ?

Respect.

I think they become common around win 98. (pentium, pentium 2 era).

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!)

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.

> 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.

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

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

yes

> 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.

[0] https://arstechnica.com/gadgets/2005/04/flash2005/

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

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

> 512MB is larger

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

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.

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

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

And how long do you think data lasts on a flash drive ?

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.

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.

DVD was the one that obsoleted CD based storage.

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.

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.

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!

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

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

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

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.

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

    * sys-fs/udftools
         Available versions:  2.3
         Homepage:            https://github.com/pali/udftools/ https://sourceforge.net/projects/linux-udf/
         Description:         Ben Fennema's tools for packet writing and the UDF filesystem

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. :-)

Boom.

https://youtu.be/zs7x1Hu29Wc?t=160

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.

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?

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.

Nope. They don't (spin at a constant rpm). Perhaps that's not so surprising; after all, it's not vinyl.

Furthermore, varying rpm is explicitly mentioned in the headline post.

Also explained here...

https://www.repairfaq.org/REPAIR/F_cdfaq5.html

While the CD data format is defined in terms of constant linear velocity[1], and CD data is always written at a fixed linear density (plus or minus a small margin of error), some drives are, under ideal conditions, capable of both reading and writing this format in CAV mode, as addressed briefly in the "Writing Modes" section of the linked article,

http://www.osta.org/technology/pdf/cdr_cdrw.pdf#page=15

In CAV modes, data rate — and laser power, in the case of writing — is a constantly increasing function of the radial position of the read/write head.

[1] Though this fixed velocity — and, by extension, data density — is allowed to vary from disc to disc. Assuming the standard (4.3218 Mbit/s raw) data rate, any velocity between 1.2 m/s and 1.4 m/s is permitted, but must then remain fixed within IIRC, a +/- 0.01 m/s margin of error.

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.

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).

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?

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.

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.

As far as I know, some versions of macOS have also aimed to keep frequently used files (such as core system libraries or executables) in those outer/"earlier" sectors.

I think Apple even had a marketing term for this, which I unfortunately can't recall.

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.

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.

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

https://xkcd.com/397/

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.

https://www.oreilly.com/library/view/pc-hardware-in/05960051...

https://www.pctechguide.com/cd-rom/cd-rom-truex-technology

I had a 48x drive later... this thing (and more the horror stories of it) kind of scared me... always made sure my leg is a little away from it while reading full speed.

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).

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

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.

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,.

The fact that it's WORM media also makes sense for medical images, where you really don't want them to be editable.

My hospital distributed all my CT, PET and MRI imagery on DVD. When I had to travel cross country to a specialist, I'd ripped them all and brought a thumb drive - which the new hospital refused to deal with. I had to stay up all night burning a set of DVDs for them from the the iso images. (And even though I had them all available via dropbox - the hospital didn't allow access to the internet at large.)

Sounds like the hospital had their infosec well in hand. That's rare.

Add in autoplay.inf to the burned CD, and we'll see...

While both types of removable media represent a risk of malware, a USB device represents a very real electronic threat of damage to equipment. You can easily inspect a CD-ROM or DVD disc and confirm that it is what it claims to be. You cannot inspect most USB thumb drives without destroying them, and they could be disguised keyboards, keyloggers, wireless exfiltration, or device destruction devices.

I am really sort of annoyed by the step backwards we've taken from tapes and optical discs into "this really smart device that happens to store data wants to interface with as many computers as possible". It's icky for those who instinctively understand and practice good infosec hygiene.

I think the "step backwards" is largely due to the rise of flash memory, which requires an electrical interface. That said, electrical destruction aside, the threat of removable media "becoming something else" is avoided if you use dedicated storage interfaces instead of USB, like SD/TF/MMC/etc.

>>less prone to degredation

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

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.

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.

https://github.com/Parchive/par2cmdline

yup, that's what I do for my longterm archives.

BTW, new hardware instruction optimized version: https://github.com/animetosho/par2cmdline-turbo/

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.

Buy some fresh ones while you can.

I will be honest I have kind of given up on trying to maintain a lot of these systems. Some I am still giving love but every year it gets a little harder, particularly with weird power supplies, dying capacitors and (now) odd ball storage systems.

About 3 months ago I finally had to sacrifice a PowerMac G5 (Steve Jobs Folly as I called it), I kept the case and it is now a semi-sleeper PC but the original G5 board was dead as a dodo and not willing to go any further. The heat sinks on that thing was intense!

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

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.

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

Makes sense, I think Verbatim were also the last ones producing DVD-RAM. I still have a handful of their hardcoat ones, they are like using a big stable floppy disk, no need for any kind of burning software you can literally format them to any filesystem.

CD-R's I bought a distributor case of Taiyo Yudens back in like the early-2000's, I have a few hundred left and use them in legacy stuff sometimes. They didn't get cd rot, all the CMC Magnetics CD-R disks (produced under many names) suffered cd rot within 10 years.

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

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

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.

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?

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.

Modern cars all seem to have integrated units. Even before but LCDs were the norm, so that's not a sole excuse :-/

(fyi it is my 2004 wrx that has a double din cd changer. I go car shopping every year or two, and I stick with my trusty Scooby every time :)

Oh gawd no.

I have predictable functional big buttons and levers to do what I need. The $200 units (let alone cheaper ones) have 2mm buttons and a freaking remote control! Do not get me started on modern car UI :-)))

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).

But of course, Alec from Technology Connections has us covered: https://www.youtube.com/watch?v=TCTWyNstpD0

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

https://news.ycombinator.com/item?id=33117813

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.

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.

https://www.ebay.com/itm/183510730139

Still remember when I got one of the first CD-R drives in school (we funded it together with 2 other school mates). Required an expensive SCSI card (IDE drives came later) and that you do not touch the PC during a "burn" because that could potentially empty the buffer and you can throw away the CD-R blank. Got me kind of famous at the schoolyard to have a CD-R drive, mostly copying audio CDs.

I can't forget the first home-copied CD I bought. It was GTA (1!) from "this one guy" in school that had a drive obviously. Payed 20 DM (german mark, about €10) for it, that was extremely pricey, haha. ...GTA did run best using the motorcycle on my 486 ;)

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...

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.

> 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.

Some movies also had a data section on DVD

Oh so that is why I could put the Tomb Raider 2 disk in the CD drive and listen to the music!

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. :(

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.

[1] https://archive.org/details/RedBookAudioRecordingCompactDisc...

[2] https://archive.org/details/understandingandservicingcdplaye...

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

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

That would be something like LaserDisc with BluRay media LOL

Or BDXL with 320 layers...

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…

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

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