Wednesday, October 22, 2008

Optical Drives, explained

Here is one of those hardware posts I warned you about -- but there's method to my madness (or is it madness to my method?). I bring up this subject because most commercial software comes on CD-ROM or DVD-ROM discs -- and I often distribute free-software compilations on CDs that I write myself (I write the discs, not the software). Live-Linux CDs and DVDs are another related item.

In June of 1985 I was at the Consumer Electronics Show in Chicago. Atari introduced its new Atari ST series -- but the item that most interested me was the CD-ROM drive add-on that was being shown with it. The only demonstration CD they had at that time was the first edition of Grolier's Encyclopedia. When I discovered that a CD-ROM disc could hold 640 megabytes (MB) of data, I was amazed (then-current small business/consumer-grade hard drives at the time maxed out at about 40 MB). I knew that big changes were coming at last (I had discussed the possibilities of CD and LaserDisc data storage with an engineer about 6 years earlier).

All the drives and discs I will be talking about share the same form factors (standardized size and shape) and are backward-compatible with earlier types; this means that a Blu-Ray burner will read (and write) CDs and DVDs as well. With the right software, media discs (audio and movies) can be played on the attached PC. There are different drive form factors for desktop and laptop PCs; within each class the drives are usually interchangeable. Due to physical (size) limitations, laptop drives read and write discs at a somewhat slower rate than desktop drives. For this reason, and to reduce wear-and-tear on the internal drive, I often use an external USB-connected drive with a laptop.

Each generation of discs and drives has held more data than the previous generation. CD capacity is 640 MB to 700 MB (depending on discs). DVD capacity is 4.7 gigabytes (GB) for a single-layer disc, 8.5 GB for a dual-layer disc. Blu-ray discs hold 25 GB on a single-layer disc, 50 GB on a dual-layer disc. There are indications that a next-generation Blu-ray disc may hold as much as 200 GB on a single CD-sized platter.

Typical 50-100 quantity prices for writable media range from about 15 cents for a blank CD-R, to 25-50 cents for a single-layer blank DVD, $1.50-$2 for a dual-layer blank DVD, up to $8-$15 for a single-layer Blu-Ray BD-R disc, and $25-$30 for a dual-layer BD-R disc (1-25 quantity). I expect the BD-R media prices will come down over time when the volume ramps up -- when I first got my CD burner, 4x blanks were about $1.50 each. There may be more about the optical media itself in a future installment.

The first iteration was the CD-ROM drive. Starting out at a read-rate of 1x (the same speed as an audio CD, about 150 kilobits-per-second), speeds soon ramped up. Microsoft's MS-DOS soon had an add-on that allowed DOS to read the CD file system, as did most other computer operating systems at the time. Current desktop optical ROM drives read (transfer data from) CDs at a 48x-52x rate -- but very few (if any) CD-ROM-only drives are currently being manufactured.
: CDs (older drives -- those manufactured prior to 1998 -- will probably not be able to read CD-R or CD-RW discs).

Next was the DVD-ROM drive, introduced in 1997. Starting out at a read-rate of 1x (the same speed as a DVD movie, which is about 4x faster than a 1x audio CD) it, too, quickly ramped up in speed. Current optical ROM drives read DVDs at a 16x-20x rate.
Compatibility: CDs & DVDs (older drives manufactured prior to 1998 may not be able to read writable media: CD-R, CD-RW, DVD-R/RW, or DVD+R/RW discs). A new DVD-ROM drive will set you back about $20-25.

At about the same time as the DVD-ROM was introduced came the CD "burner" (writer) drive. As CD write speeds ramped up above about 8X, a problem became evident -- the computer could not always transfer data to the drive consistently and the data interruption (known as buffer underrun) led to write failures. Sanyo developed what is now referred to as buffer underrun protection (sometimes called BURN-proof) -- all current writable drives (and the software for them) keep track of where they are on the disc during the write process and can pick up where they left off if the buffer (internal temporary storage memory) empties during a write cycle. Current optical ROM drives write (transfer data to) CDs at up to a 48x-52x rate.
Compatibility: read/write all CDs. A new CD-writer drive will cost about $20 -- I paid nearly $300 for my first 4x CD writer in 1999. Note: all older drives will require a
firmware update to write some current discs.

It was not long before a DVD-ROM drive was combined with a CD writer to make what is now called a combo drive, with all the features of both. These have mostly been superseded by full-featured DVD writers.
: read/write all CDs and read all DVDs. Note: all older drives will require a firmware update to write some current discs.

Next came the DVD burner. First-generation drives wrote DVD+R/RW and CD-R/RW only; DVD-R/RW drives and discs soon followed from a different industry consortium and could burn CDs as well. In general, the + and - drives could read (but not write) each others' discs. Current DVD writers are +/- write-compatible, but check the front-panel markings on a particular drive to ensure it will write the discs you feed it. Current desktop DVD-writer drives write single-layer discs at 16x-20x; Current laptop DVD-writer drives write single-layer discs at 6x-8x. Dual-layer discs are written at 4-8x depending on the type of drive and the media used.
Compatibility: read/write all CDs and read all DVDs. DVD write-compatibility varies with the drive; newer drives (since about 2004) write all types. Note: all older drives will require a firmware update to write some current discs.

The newest optical-disc formats are HD-DVD and Blu-ray, though the HD-DVD format has already fallen by the wayside (much to the chagrin of Microsoft). There are Blu-ray combo drives that add Blu-ray ROM and movie-reading capabilities to a DVD-burner drive.

The pinnacle of the optical-drive heap is the Blu-ray writer drive. Current Blu-ray writers can write BD-R media at up to 8x, which is a whopping 288 megabits (Mb) per second -- a nearly 2000 times faster data-transfer rate than a 1x CD at 150 kilobits (kb) per second.Compatibility: read/write all CDs, DVDs, and Blu-ray media.

Sunday, October 12, 2008 v3.0 is out!

One of my favorite free application suites now has a new version available -- (OOo) version 3.0.0 -- here's a good direct link:
If you want more information or are new to OOo, you can go to the main site and get the download link from there. You can also find FAQs (frequently asked questions) and tutorial links there as well. v3.0.0 is a substantial update from v2.4.1 and a better-than-ever replacement for the bloated, too-costly Microsoft Office series.

If all you want is a decent free word processor, try AbiWord and its related tools and plug-ins. I actually run both OOo and AbiWord as a cross-check for text-formatting problems.

Clickjacking -- and a fix

There has been a lot of talk this week about a newly discovered vulnerability in all modern browsers running under any operating system, including all versions of Microsoft Windows, Linux, BSD, and Mac OS X. Called clickjacking, it's a means of hijacking (redirecting) clicks on links within browsers:
Computerworld article or

Fortunately, a useful fix is available. I have recommended the use of the Mozilla Firefox browser for quite a while. It runs on Windows, OS X, BSD, and Linux. The important information here is that Firefox supports add-ons -- plug-ins that add useful features. That's where the solution comes from; it's yet another reason to (mostly) abandon Microsoft's Internet Explorer under Windows.

I am a long-time user of the NoScript add-on for Firefox, which blocks scripts (which are usually JavaScript-based) from running in the browser -- unless you allow it on a per-site basis (easily managed). It has just been updated to add useful protection against this very vulnerability.

Managing add-ons in Firefox is pretty easy. Go to the Tools menu in the menu-bar top-of-page, select Add-ons. When the dialog window opens, enter noscript in the search box near the top of the window and install the add-on from there. There may be other useful add-ons of interest to users; see the Firefox add-ons page for more information, including the ability to browse add-ons by category.

Wednesday, October 1, 2008

Secure your Windows PC -- for free (Part 1)

One of the ironies of modern computing is the fact that users pay for Microsoft Windows either directly or indirectly, but due to the security holes in Windows most users usually pay again for protection -- most of which should never have been needed in the first place. For example, there are any number of companies lining up to sell you anti-virus, anti-spyware, and firewall software. Even Microsoft itself will sell you a $50-a-year subscription-based product (Microsoft One Care) to fix problems that should never have existed in the first place. This sort of double-dipping certainly doesn't seem fair. Frankly, this is one of several reasons that I mostly use Linux -- while I run it I have no problems with viruses or other malware.

Fortunately, there is free software available that can effectively improve your Windows security just as well as any paid software or service. The trade-off? It takes a little bit more effort to gather it all together and maintain it -- but the knowledge is useful and it does pay off. It's also true that users must be careful, as some anti-malware software is more resource-intensive than others, sucking up CPU cycles like a Dyson at full speed. Combining two such programs can bring even a multi-core system to its metaphorical knees. When this is the case, I will mention it. Also, be aware that there are malicious software programs out there disguised as useful utilities (see here and here for lists and information on some of them).

There are several decent free anti-virus utilities available. Most are effective -- some even more so than the market leaders (though, to be fair and honest, I hear good things about Symantec's soon-to-be-released commercial Norton 2009 suite). There are four that I use on a regular basis, depending upon the version of Windows, the nature of the problem, and the speed of the PC. They are roughly equally effective, though the functional mechanisms do differ. Also be aware that the first three free versions listed are for private home use on one PC only -- institutional and commercial use are not allowed -- though the AVG software (for example) has a fully-functional 30-day trial version available to all. Comodo's package does not have the limitations listed, one of the reasons that I recommend it highly.

One of the better on-line comparisons of the first three free anti-virus utilities discussed here is available here, though it's a bit out-of-date. Rather than go into too much detail in this post, it's a good article to check out as a start. Also realize that most of the packages mentioned here have commercial versions available that are more feature-complete. Buy them or donate if you can afford it; the free versions have to be supported somehow. ClamAV, The last package listed here, has a whole different approach that can be useful, since there's a version that runs under Linux and BSD.

AVG Free Anti-Virus
The newest version of AVG Free Anti-Virus is probably more accurately described as a suite. It includes not only anti-virus software, but also a link-scanner and anti-spyware capabilities. It's what I usually install; the reasons I might install one of the others include being second-machine-on-a-network (the Free-AVG license is limited to one machine per network) and older/slower PCs (it's more of a resource hog than the older versions of AVG were). There is also a version available that runs under Linux; see the ClamAV section to see why this is useful.

Avira AntiVir Personal
This package is nominally the best-performing of the programs listed here (usually) -- but real-world performance has them more evenly matched. One minor gripe is the advertising nag-screen pop-up that is displayed at boot-up, though this is a reasonable attempt to sell the retail product.

avast! antivirus Home Edition

Despite having a somewhat-clunkier user interface than the others (in my opinion), this is still a useful and effective package.

Comodo Internet Security
Note: Comodo AntiVirus is now part of the Comodo Internet Security suite with the firewall integrated. I use this on one of my slower PCs because it rarely sucks up too much in the way of resources -- and I now recommend it over AVG for general use. It seems to be quite effective, with an added bonus: commercial and multi-PC use is OK.

This is the outsider of the bunch, because the philosophy behind it is drastically different from that of the others. It's GPL open-source software that was originally designed to work on Unix and Linux mail servers and gateways to protect downstream Windows-based clients; there's now a version for Windows as well. While they are not kept as up-to-date as some of the other utilities listed here, they are useful tools nonetheless.

Why is a Windows-virus utility that runs on Linux/Unix/BSD useful? For the simple reason that it allows a technician or user to work on Windows from the "outside." Running a virus checker from within Windows is very much like working on an automobile engine while it's running -- there are times it's just easier to work on it when it's turned off. This is made possible by the use of a free "live" Linux CD or DVD such as Knoppix, System Rescue CD, or Trinity Rescue Kit (among others). In an extreme case I may hook the infected Windows-installation hard drive to my own PC running Linux via an external USB adapter.

Since the Clam anti-virus software is an on-demand scanner, it can usually be run under Windows even when other anti-virus software is running in the background.

Part 2 of this series will cover anti-spyware and related software.