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Why is an operating system software
loaded from hard disk than from a rom
chip?
I was asked this question and I am unable to find the answer.
Can someone explain?
The easiest answer is ease of patching and extensibility. ROM cannot easily be patched - though with some permanent storage location and some creativity and foresight when building your initial ROM, you can patch it with some hook code.
Size of ROM isn't a great answer. CD/DVDs are a permanent location and could be used, though not ROM 'chips'. ROM chips can be made large enough to handle an OS (heck some versions of Linux fit on floppies not too long ago) and wouldn't be that expensive, though worse than a DVD for distribution costs.
Replacing an OS via a new ROM chip isn't that attractive, but if you just plugged in a new PCI card, would that be so bad? We do that already so this isn't a great argument either.
Access speed to a ROM chip, generally, will be much superior than to a harddrive so you would get a performance boost this way, so that's actually a plus. Also having a ROM makes it that much harder for malware to infect the OS - another plus.
So, in general, I see many pluses for a ROM based OS vs a RAM based one. Nice question.
An OS on a harddisk can be replaced by installing a new one onto that disk, and it can be easily updated.
If your OS is burnt into a ROM, that won't really work. Replace the OS?? Rip out the ROM chip and stick in a new one.... not a very attractive suggestion! (at least not for a desktop PC or notebook)
I guess iOS/Android is not loaded from a hard disk, so that depends.
Size and demand. Flash chips large enough to hold an OS that most people want/would want to run are ridiculously expensive.
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Laptop Model: Sony, Vaio SVE141D11L
Hi! I have two problem. first is when I turn on my laptop I see this Operation System Not Found, and the second problem is, I can't boot bios page, because my keyboard is not working. so, now how can I fix my problem? I mean how can I get into the bios page?
not sure why your keyboard is not working, could use more information - best way to access bios would be to plug in a basic USB keyboard and press key as says on bios screen.
Wireless keyboards/dongle keyboards most likely will not work.
Some other easier things you could try:
It sounds like your memory device(HDD/SSD/M2) might still be working but OS is corrupt so insert an OS installation media (usb, cd etc) if your on Microsoft windows you can get an windows iso tool online, as your computer cant detect OS it should boot into any bootable media.
open up your laptop remove cmos battery for over a minute which should reset your bios in-case keyboard is messed up due to settings
remove your internal media device and plug it into another computer to check if its readable.
Hope this helps
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I am trying to understand, what is an OS image and VM image and how they are different?
An OS Image commonly refers to a collection of the programs and data files needed to make an operating system functional. That is a minimal definition; but an image needn't be minimal.
A Virtual Machine image commonly refers to all of the state: memory, device registers, etc... of a virtual machine. In contrast to an OS Image, a Virtual Machine can be restarted after halting; whereas an OS Image restarts from the beginning. A system image commonly refers to the equivalent of a virtual machine image for a real hardware machine.
Why do these terms exist? When an operating system starts, there is little to no functioning system software on the target machine; so the first level of starting (bootstrapping) is to put some lump of something into RAM, and start executing it. That lump might be an operating system, or may be a small intermediate system that will then load the actual operating system (or load yet another boot loader). An example is grub or u-boot.
An intermediary system may be more functional than to just load a lump and jump. It might understand file systems, and be able to parse device database; thus construct an appropriate OS image for the target hardware on the fly. The division of labour is a compromise chosen by the system designer.
Intel based systems add an incredibly complex intermediary into all of this with a system called ACPI which sits underneath the Extensible Firmware Interface. The A in ACPI stands for Advanced, I suppose new and improved was too transparent.
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Some media have reported that a new hardware bug in Intel processors, allowing user mode processes to access kernel mode memory, has been discovered:
It is understood the bug is present in modern Intel processors
produced in the past decade. It allows normal user programs – from
database applications to JavaScript in web browsers – to discern to
some extent the layout or contents of protected kernel memory areas.
The effects [of fixes] are still being benchmarked, however we're
looking at a ballpark figure of five to 30 per cent slow down,
depending on the task and the processor model.
After the bug is fixed, which slowdown am I to expect for multicore floating point computations?
To my understanding, only the performance of switches between kernel and user mode are affected. For example, handling a lot of I/O is a workload where this is frequent, but CPU-intensive processes should not be affected as much.
To quote from one article that analyzes performance of the Linux KPTI patch:
Most workloads that we have run show single-digit regressions. 5% is a good round number for what is typical. The worst we have seen is a roughly 30% regression on a loopback networking test that did a ton of syscalls and context switches.
...
So PostgreSQL SELECT command is about ~20% slower with KPTI workaround, and I/Os in general seem to be impacted negatively according to Phoronix benchmarks especially with fast storage, but not gaming performance, Linux kernel compilation, H.264 encoding, etc…
Source: https://www.cnx-software.com/2018/01/03/intel-hardware-security-bug-fix-to-hit-performance-on-windows-linux/
So, if your FP computations rely mostly on in-memory data shifting and not I/O, they should be mostly unaffected.
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The question actually is :
If I have some processor named x
I have 3 Operating Systems named a,b,c
Now how can I decide that which operating system controls the processor ?
What is the basic understanding between the processor and Operating system ?
And the above 3 operating systems are not of different versions from same company..
To be specific how Android hardware is different from iPhone hardware and why can't iOS be installed on Android hardware...??
Thanking you..
You are actually asking a question which shows your lack of understanding of OS, CPU and other technical terminologies.
Actually, You need to study the basic of Os and CPU to get a deep understanding on the topic. But, I will definitely help you out by defining both the terminologies.
Your computer's operating system has two main objectives in its management of the central processing unit, or CPU. First, the OS makes sure that as many processor cycles are used for work as possible.
Second, the OS schedules the processor's attention among the demands of different processes. Processes are actions that can be controlled and are the basic units of software with which the OS communicates. A process may be a task, such as a virus check, that runs in the background so you never even know it's working. It also may be one of several tasks that an application, such as a spreadsheet, executes at your request. In a multitasking OS, the OS has to switch the processor's attention between competing processes many times per second because the processor can only do one thing at a time.
Briefly summarizing :
A processor is the 'engine' of the computer - it runs all the software and moves data around. The best processor in general has more cores (core i7), and a higher speed.
An operating system is the 'traffic cop' of all the software on the computer - it's software that controls how all the other programs on the computer work together and share the resources of the computer.
Hope you have got an idea :)
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I need to learn the basic knowledge of OS, kernel and CPU architectures since some jobs do require those background.
Is there a good book or online resource that I can refer to.
I don't know if you had a specific OS in mind, but one of the best books on how the Windows operating system works "under the hood" is called Windows Internals. It describes in detail how everything from the kernel, to device drivers, and the file system all work.
If your looking for a good book on how CPUs and processors work, in general, I recommend Computer Architecture: A Quantitative approach. Very good info there!
Also, some good resources on how CPUs work, with perspective to programmers, can be found from the Intel technical library. Everything is free to download there and it makes for some good reading!