One of two operating modes of modern microprocessors. In this mode, otherwise applicable speed restrictions aren’t set in stone and the normal 640MB can be exceeded. In the other mode – real mode – this is not the case and 640MB is the absolute limit. Additionally, the processor also protects certain information in its memory, thus the name protected mode.
Technipages Explains Protected Mode
Protected mode, or in its full name protected virtual address mode is an operational mode only found on x86 compatible CPUs. By default, a processor that was just powered up will enter the other mode, real mode, first, and then later the user can switch over by using the control register.
First introduced in 1982, protected mode was subsequently used to improve later generations of CPUs. While the first processor to feature it was the Intel 80286, every generation since has had it, and other CPU manufacturers also use it. That particular generation had several shortcomings compared to competing products and so wasn’t very popular at all, but it did mark the beginning of protected mode. Later generations brought with them new registers and other enhancements, which benefitted both modes.
One of the advantages of protected mode is that, with operating system support, it supports pre-emptive multitasking. That means that it lets programs share the same memory space in order to be ready for future tasks. That means that processes can be completed faster overall and that resources are ready quicker.
Common Uses of Protected Mode
- Protected virtual address mode, is an operational mode of x86-compatible central processing units.
- IBM devised a workaround allowing easier entry into protected mode.
- Virtual 8086 mode was a later addition to protected mode.
Common Misuses of Protected Mode
- Protected mode keeps a CPU from overheating.
