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Comment: Re:360K already double-sided (Score 1) 173

by crow (#48620241) Attached to: Backblaze's 6 TB Hard Drive Face-Off

Thanks for finding that source! I was looking at the list of floppy disk formats on Wikipedia to respond, and it didn't have that.

80 cylinder, 96 TPI

This was the second type of 5.25" drive made, and the least popular (and known) of the three types of drives. These double the capacity of the original drive by doubling the number of cylinders (tracks) from 40 to 80. They use the same media as the the 40 cylinder 48 TPI drives, but it is certified (tested) on all 80 tracks, as opposed to the standard disks which were only certified at 40 tracks.

These drives were never common on PCs, although DEC used a single sided version called the RX-50, in the DECMate word-processor, the DEC Rainbow and several other DEC computers, including the PDP-11 and the VAX.

Other than the DEC RX-50, these drives were almost always double sided, and recorded in double density MFM. They had a capacity of around 720K. Like the 40 track drives, they used 300oe media, and the drive rotates at 300 RPM

So apart from one very rare example, if you're talking 5.25" disk floppies, 360K meant double-sided. I expect the vast majority of people cutting out the notches to flip over their disks were using Apple II, Atari, or Commodore computers. In that realm, 90K was SS/SD and 180K was SS/DD. Most users didn't have double-sided drives until the IBM PC started using 360K DS/DD disks.

Comment: Just in time. (Score 1) 219

by crow (#48589231) Attached to: Seagate Bulks Up With New 8 Terabyte 'Archive' Hard Drive

I am just about to build a FreeNAS or NAS4Free box. I was planning on running three 4TB drives to give me 8TB usable, but I'm probably better off with a pair of these. I'm mostly using the storage for TV recording, so the slower speed is fine. If the slower speed also means lower power, then it's a big plus.

Comment: In Massachusetts... (Score 4, Informative) 1051

by crow (#48582049) Attached to: Time To Remove 'Philosophical' Exemption From Vaccine Requirements?

Mass. Gen Laws ch.76, Â 15:
"In the absence of an emergency or epidemic of disease declared by the department of public health, no child whose parent or guardian states in writing that vaccination or immunization conflicts with his sincere religious beliefs shall be required to present said physicianâ(TM)s certificate in order to be admitted to school."

So there's broad religious exemptions such that anyone willing to claim them can skip the process, but if there is a serious outbreak, then suddenly the exemption goes away. That's not a bad compromise.

I haven't heard of the state ever declaring such an emergency, but I hope they are ready to do so before an outbreak becomes a full epidemic.

Comment: Nitpick on the linked article (Score 1) 222

by crow (#48568669) Attached to: Dad Makes His Kid Play Through All Video Game History In Chronological Order

At the top of the article, it shows an Atari 2600 in front of a TV. Displayed on the TV is Pac Man. But it isn't the 2600 version. It looks like the 800 version, or possibly the 5600 version (which was only slightly different).

Mixing up the graphics like that is just wrong.

Especially when the 2600 version of Pac Man was notorious for being so horribly bad. If only it had looked like that.

Comment: Re:obviously they should track the sun (Score 2) 327

by crow (#48511335) Attached to: You're Doing It All Wrong: Solar Panels Should Face West, Not South

Tracking the sun is out of the question when it comes to rooftop solar on sloped roofs. You're pretty much stuck with having the solar panels match the slope of the roof.

For ground-based installations or for large flat roofs, you would think it makes sense, but it would seem not, as I see solar farms all over the place (in Massachusetts), and they're all fixed installations. If it made economic sense to track the sun, then I'm sure the large farms would be doing it. Even with the production credits (SRECs they call them here), where you can get upwards of $.50/KWh, they're still not tracking the sun.

Can someone who has actually looked at the costs of sun tracking comment? I keep seeing assertions like the poster above, but I've never heard real numbers.

Comment: Re: Mass produce! (Score 1) 194

by crow (#48471113) Attached to: Jackie Chan Discs Help Boost Solar Panel Efficiency

Actually, using electricity to produce fuel is something that can have practical use:

http://www.theregister.co.uk/2...

In short, it's relatively easy to deploy a small nuclear reactor (much like one found in a submarine) to an operational base. If the excess power can be used to synthesize fuel, then that fuel doesn't have to be trucked in, which is a massive savings in a combat zone.

Also, it's a potential way of storing excess production, such as when demand drops overnight.

Comment: Electricity vs. oil (Score 4, Interesting) 194

by crow (#48470289) Attached to: Jackie Chan Discs Help Boost Solar Panel Efficiency

Electricity and oil are both energy. You can substitute one for the other, though obviously there's advantages for certain forms in certain uses.

For home heating, oil, natural gas, and electricity are all viable depending on the cost. Right now gas is the cheapest and electricity is, in most places, the most expensive. It would take a lot of progress to get electricity to be the most economic solution for heating.

For aircraft, the weight of batteries rules them out.

For cars, Tesla is proving that electricity is an option. I know that we just signed a contract for solar panels on our house to produce more than we currently use on the assumption that we'll need the extra production to power our next car.

Comment: Re:Easy with Gentoo (Score 2) 106

by crow (#48231633) Attached to: Building All the Major Open-Source Web Browsers

I agree that it should be easy. My point wasn't to rely on distributors for building. It was that the work has already been done for major projects like the ones listed, so you can get a sense of their build complexity by looking at what they had to do.

For example, here are some ebuild sizes:
gcc-4.9.1 1556 bytes
mythtv-0.27.4 9796 bytes
firefox-33.0 11698 bytes
libreoffice-4.3.1.2 18473 bytes
chromium-40.0.2194.2 18610 bytes
netbeans-ide-8.0 29367 bytes

That's a rough approximation of complexity. Sure, you can have a long but simple ebuild with comments and trivial stuff. You can hide lots of complexity in an eclass file. But it's a starting point.

As you can see, a project that uses a typical autoconf setup like gcc, while a very large project, has a very simple ebuild script. Meanwhile, Chromium and LibreOffice are quite complex. I don't know much about netbeans, but it's the largest ebuild in Portage right now. Other large ebuilds include openldap, ghc, php, and ati-drivers.

Comment: Easy with Gentoo (Score 5, Informative) 106

by crow (#48231055) Attached to: Building All the Major Open-Source Web Browsers

Of course, if you use a source-based distribution, it's easy, but that's not the point. If you download the source and build it yourself, you'll have to learn a bit about how they manage the build environment. You'll have to handle being sure all the dependencies are installed. You'll have to figure out any configuration options.

That's exactly what people who make distributions do. If you want to see how complicated the build is for any piece of software, just look at how complicated the build scripts are for various distributions. I expect you can find these for the binary distributions. With Gentoo, just look at the ebuild file.

Comment: Harder if mildly effective (Score 1) 178

by crow (#48092025) Attached to: Ebola Vaccine Trials Forcing Tough Choices

The difficulty in determining the effectiveness of the vaccine when you give it to everyone is dependant on how effective it is. If it reduces the chances of exposure resulting in infection by 10%, then yes, it will be tough to show that it's not useless. However, if it reduces the chances by 90%, it will be quite obvious.

No hardware designer should be allowed to produce any piece of hardware until three software guys have signed off for it. -- Andy Tanenbaum

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