No, it is not possible to construct a secure operating system for those computer systems which do not provide a privileged mode of operation in hardware.
define and explain hardware protectoin
privileged EXEC
Privileged mode has access to the entire router or switch configuration. User EXEC mode only has limited options. Specifically, to do any configuration changes, you need to enter privileged mode first.Privileged mode has access to the entire router or switch configuration. User EXEC mode only has limited options. Specifically, to do any configuration changes, you need to enter privileged mode first.Privileged mode has access to the entire router or switch configuration. User EXEC mode only has limited options. Specifically, to do any configuration changes, you need to enter privileged mode first.Privileged mode has access to the entire router or switch configuration. User EXEC mode only has limited options. Specifically, to do any configuration changes, you need to enter privileged mode first.
# or Router#
ctrl-p
Scheduling has to do with how the job scheduler decides which task will have the CPU and for how long. This is the technique of multi-tasking; the appearance of running multiple processes at the same time (when they really aren't). Context switching occurs when a process needs to do something in a privileged way, such as requiring communication with another hardware device. When the process is typically running it is in user mode, which is a non-privileged mode of operation. It has to context switch into kernel (privileged) mode to do things, then switch back. The main difference between the two is that context switches happen in a non-predictive manner in the same program/process, and job scheduling is predictable (to a point). Then again, they serve different needs of the Operating System, as well.
In any environment, in order to execute a privileged instruction you have have to switch from user mode to kernel mode, hence a context switch.
R1#
Kernel mode is considered a 'privileged' mode, meaning that code executing in that mode can have access to any part of the system, memory, devices, etc. There are no limitations on what it can do. User mode only allows certain operations. Anything requiring any amount of privileged must request the kernel to do things on their behalf. User mode is not a privileged mode and is therefore restrictive in terms of accessing memory, devices, etc.
There is no protected mode in the 8085 microprocessor, therefore, there are no instructions that are considered privileged.
privileged EXEC