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Comment Reminds me of the Cache Kernel. (Score 2, Interesting) 631

The part of the article where Probert discusses the operating system becoming something like a hypervisor reminds me of the Cache Kernel from a Stanford University paper back in 1994.

The way I understand it, the cache kernel in kernel mode doesn't really have built-in policy for traditional OS tasks like scheduing or resource management. It just serves as a cache for loading and unloading for things like addresses spaces and threads and making them active. The policy for working with these things comes from separate application kernels in user mode and kernel objects that are loaded by the cache kernel.

There's also a 1997 MIT paper on exokernels ( The idea is separating the responsibility of management from the responsibility of protection. The exokernel knows how to protect resources and the application knows how to make them sing. In the paper, they build a webserver on this architecture and it performs very well.

Both of these papers have research operating systems that demonstate specialized "native" applications running alongside unmodified UNIX applications running on UNIX emulators. That would suggest rebuilding an operating system in one of these styles wouldn't entail throwing out all the existing software or immediately forcing a new programming model on developers who aren't ready.

Microsoft used to talk about "personalities" in NT. It had subsystems for OS/2 1.x, WIn16, and Win32 that would allow apps from OS/2 (character mode), Windows 3.1 and Windows NT running as peers on top of the NT kernel. Perhaps someday the subsystems come back, some as OS personalities running traditional apps, and some as whole applications with resource management policy in their own right. Notepad might just run on the Win32 subsystem, but Photoshop might be interested in managing its own memory as well as disk space.

The mid-90s were fun for OS research, weren't they? :)


New Rules May Raise Cost of Buying Gadgets Online 171

ericatcw writes "Buying your next laptop or smartphone online could suddenly get a lot more expensive if a little-known US Department of Transportation proposal to tighten rules around the shipment of small, Lithium-Ion battery-powered devices by air goes through, says an industry group opposing the move. The changes, designed primarily to reduce the risk from Lithium-Ion batteries, would also forbid air travelers from carrying spare alkaline or NiMH batteries in their checked-in luggage, according to the head of the Portable Rechargeable Battery Association. The proposal is under review until March 12. It can be viewed and commented upon by members of the public."

Psystar Activation Servers Down? 245

An anonymous reader writes "I purchased Rebel EFI in support of Psystar's crusade back in October. Just 3 short months later, I have no support. I found this out when I upgraded my hard drive and installed Snow Leopard using Rebel EFI. The program can no longer 'phone home' to activate or download/install drivers. This is a direct contradiction to Psystar's promise posted on their website: 'Psystar will continue to support all of its existing customers of hardware and software through this transitional period. Warranties on hardware will continue to be honored as long the customer has a valid warranty. Rebel EFI support for existing customers, as always, will remain exclusively available through email and the built-in ticket interface.' Has anyone else run into this issue? It has been 9 days with no response from Psystar by e-mail or phone."

Comment Re:Iron Man's Suit Defies Physics -- Mostly (Score 2, Interesting) 279

Hydrogen peroxide powered rocket packs fly for around 30 seconds, because they have a specific impulse of around 125, meaning that one pound of propellant can make 125 pound-seconds of thrust, meaning that it takes about two pounds of propellant for every second you are in the air. Mass ratios are low for anything strapped to a human, so the exponential nature of the rocket equation can be safely ignored.

A pretty hot (both literally and figuratively) bipropellant rocket could manage about twice the specific impulse, and you could carry somewhat heavier tanks, but two minutes of flight on a rocket pack is probably about the upper limit with conventional propellants.

However, an actual jet pack that used atmospheric oxygen could have an Isp ten times higher, allowing theoretical flights of fifteen minutes or so. Here, it really is a matter of technical development, since jet engines have thrust to weight ratios too low to make it practical. There is movement on this technical front, but it will still take a while.

John Carmack

Comment Easier way to get on a billboard in Times Square (Score 1) 216

I asked my daughter if she wanted her picture in Times Square. She said she's been there and done that. 21 months, thanks for asking.

Seriously, Time Magazine is posting submitted pictures on a billboard until they announce the Person of the Year. If they use your picture, they send you an email with a link to the photo of the billboard with your picture on it. It took a day for her picture to make it up.

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