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Till now I used to think that embedded and real time systems are same. But when I was asked in an interview that what the difference is between the two, I was scared. I can't even get proper answer by searching in web.
It was a poor question perhaps since they are not mutually exclusive; an embedded system may be real-time or it may not. One term describes the physical embodiment of a system, the other describes its performance and response characteristics.
Embedded system describes a system that contains one or more software programmable devices but which is not itself a general purpose computer. Such a system typically has a fixed, single application rather than end-user selected and loaded software (which would make it general purpose).
However "embedded" covers a wide spectrum of systems and is not always easy to define; for example if you were writing the UMTS code for a smartphone, you might reasonably be regarded as an embedded developer, if you were writing Flappy Angry Birds 2.0 for that same phone however, you would not - so a smartphone may be both an embedded system and general purpose computer - depending on your view point. Similarly a hand-held games console's system software is embedded; the games themselves are not I would say.
A real-time system describes a system with deterministic low latency response to input events. An embedded system may be "real-time, or it might not. I would normally use the term "real-time embedded system" to be clear.
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I was looking to benchmarks and I can't see a difference. OpenGL 4.5 is same with Vulkan. Can an API effect the graphics quality?
It is a bit broad, but it cannot hurt to have The Motivation question answered.
This official video presentation discusses some of the differences: https://www.youtube.com/watch?v=iwKGmm3lw8Q
Vulkan API is a complete rework.
It also gives the programmer more control (but doing so requires him to do more, and know more).
Because of the above any graphics application also requires whole-hearted rework. Otherwise the benefits won't simply manifest. I don't keep updated, but I think big engines like UE4 and Unity still work on a way how to incorporate Vulkan in a non-naive manner.
Some benefits can be seen already in benchmarks. Though not in every benchmark. Some workload is fine for OpenGL and so Vulkan cannot show any improvement. Some aplications perhaps add Vulkan support just as an afterthought, making it unfair comparison. Some Vulkan drivers optimization may not be priority (e.g. for older GPU cards).
Main benefit of Vulkan is on the CPU side. It may manifest in other ways than FPS, such as less ventilator noise (temperature), more battery life and simply having more free CPU for other tasks.
Vulkan also gives more control to the programmer. If exploited it may also translate in other non-FPS benefits, like improving input latency and preventing hitching.
Vulkan also requires less of the driver, hopefully making it easier to optimize and GPU companies more willing to adopt it and implement it even on older cards.
Everything being the same (including the program itself as much as it can be), there should be no overall resulting image quality difference. Pixel values can differ slightly here and there though.
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I've read that every manufacturer can produce his own BIOS ,
where to find a specific BIOS interrupts list , and how to know my PC's BIOS version?
there's a lot ( IBM , AT&T , ..)
And it's really strange that the only reference is RBIL !
where to read "ALL" interrupts of specific version ?
Most BIOS vendors are compatible with the original IBM PC BIOS source, but that is a convention, not a rule. Many BIOS vendors will offer their own extended/undocumented BIOS calls.
If you are simply trying to boot, read disk sectors, print characters on the screen, etc, you should be able to manage that without having to know which specific BIOS you are running on. After all, they must be similar enough for DOS to boot!
If you really want to know what specific BIOS you have, you can look in the BIOS POST or setup screens. Look for a version or ID string. Otherwise, you can boot Windows and run the System Information tool, which can tell you. Otherwise, you can dump the F000 segment to a file and run the "strings" utility on it. Again, you probably do not need to know this, because it is irrelevant for 99% of the basic PC operations.
My favorite reference for BIOS and DOS interrupts is the Programmer's PC Sourcebook (Second Edition). It's long out of print, but I think you can still find used copies on Amazon. There are other books out there, but this is the one on my bookshelf that I have used for the last 10+ years.
If you are adverse to spending money, the Ralf Brown Interrupt List (RBIL), seems pretty comprehensive, but I have never used it personally.
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As far as I understand it, embedded software is just software (that runs on a general purpose CPU) that has little if any user input or configuration. Embedded software powers IP routers, cars, computer mice, etc.
My question is:
When (roughly) was the historical moment when embedded software was first considered cost-effective for some applications (rather than an equal technical solution not involving embedded software)? Which applications and why?
Detail: Obviously there is a tradeoff between the cost of a CPU fast enough to perform X in software versus the cost of designing hardware that performs X.
Embedded systems date from the Apollo moon landings. Specifically the Apollo Guidance Computer (AGC) - widely held to be one of the first examples of embedded systems.
Commercially in the early 1970's early microprocessors were being employed in products, famously the 4-bit Intel 4004 used in the Busicom 141-PF. Bill Gates and Paul Allen saw the potential for embedded microprocessors early with their pre-Microsoft endeavour the Traf-O-Data traffic survey counter.
So I would suggest around 1971/72 at the introduction of the Intel 4004 and the more powerful 8-bit 8008. Note that unlike the more powerful still Intel 8080 which inspired the first home-brew microcomputers and the MITS Altair, the 4004 and 8008 were barely suitable for use a general purpose "computer" as such, and therefore embedded computing systems pre-date general purpose microcomputers.
I would dispute your characterisation of what an embedded system is; if you were asking that question here's my answer to a similar question.
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I've been trying to describe the concept of platforms to some non-developer people on my team. I'm trying to explain how platforms are more than just tools and environments. For example, the Facebook Platform. How to describe the fact that the platform is more than just the website, but includes protocols like XFBML, opengraph, etc.
Facebook Platform is one example, but I would be interested if anyone has an abstracted way to describe what 'platforms' are in the tech world. I've had difficulty explaining this concept before in situations unrelated to flash.
Analogies that aren't tech related would be helpful as well.
I would say something about it being all-inclusive and extending to include all functionality that the entire ecosystem around that particular piece of software needs to thrive.
The Wikipedia page might help in putting it into words: http://en.wikipedia.org/wiki/Computer_platform
I use a "restaurant" metaphor, myself: Think of the kitchen, the bar, the dining room as components to the platform. How the decor can change in the dining room without changing the function, but can affect how customers perceive the business. How the recipes instruct the cooks, and the interactions with the wait staff can all affect different aspects of the business much like different pieces of your platform can be modified to affect different aspects of your business. Oh, and don't forget management!
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I'm new with zigbee i need you to help me learn about it and know how to implement an embedded system using it
thanks in advance
One good place to look is on the Digi site. They have several products to help you, including embedded development kits.
If you want to go Open Source, look at Source Forge. They have some open source stacks. I have not used any of them, so I cannot comment beyond knowing that they exist.
Depending on your needs, you might want to just look at XBee, which is a subset of zigbee. There are some nice development tools for XBee. I have used an XBee expansion shield with the .net micro framework and boards provided by TinyCLR to do a wireless prototype.
Creating a zigbee stack on your own would be a fairly large task, so only you can determine if there is ROI in doing so. I would be more inclined to buy it in.
Get a ZigBee Starter Kit. Lots of vendors provide one; gust Google that exact phrase.
For example: AVR 8-Bit RISC - IEEE 802.15.4/ZigBee - Tools
Or you can ZigBee on a PIC/Microchip at very low cost. http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2112