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en:multiasm:cs:chapter_3_1 [2026/03/01 13:54] – [Memory] ktokarzen:multiasm:cs:chapter_3_1 [2026/03/01 14:00] (current) – [Buses] ktokarz
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 <note info> The byte is historically assumed to be 8 bits of information and used as the base unit to express the size of data in the world of computers. </note> <note info> The byte is historically assumed to be 8 bits of information and used as the base unit to express the size of data in the world of computers. </note>
 The size of the memory installed on the computer does not have to match the size of the address space, the maximum size of memory which is addressable by the processor. In modern machines, it would be impossible or hardly achievable. For example, for x64 architecture, the theoretical address space is 2^64 (16 exabytes). Even the address space currently supported by processors' hardware is as large as 2^48, which equals 256 terabytes. On the opposite side, in constrained devices, the physical memory size can exceed what the processor supports. To enable access to memory beyond the processor's addressing space or to support flexible placement of programs in a large address space, the paging mechanism is used. It is a hardware support unit that maps the processor's address into the physical memory installed in the computer.  The size of the memory installed on the computer does not have to match the size of the address space, the maximum size of memory which is addressable by the processor. In modern machines, it would be impossible or hardly achievable. For example, for x64 architecture, the theoretical address space is 2^64 (16 exabytes). Even the address space currently supported by processors' hardware is as large as 2^48, which equals 256 terabytes. On the opposite side, in constrained devices, the physical memory size can exceed what the processor supports. To enable access to memory beyond the processor's addressing space or to support flexible placement of programs in a large address space, the paging mechanism is used. It is a hardware support unit that maps the processor's address into the physical memory installed in the computer. 
-<note info>To learn more about paging please refer to https://connormcgarr.github.io/paging/</note>+<note info>To learn more about pagingplease refer to the website 
 +https://connormcgarr.github.io/paging/</note>
  
 ===== Peripherals ===== ===== Peripherals =====
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 **Control bus** is formed by lines mainly used for synchronisation between the elements of the computer. The minimal implementation includes the read and write lines. Read line (#RD) is the information that other elements use to indicate that the processor wants to read data from the unit. In such a situation, the element, e.g. memory, puts the data from the addressed cell on the data bus. Active write signal (#WR) informs the element that the data which is present on the data bus should be stored at the specified address. **Control bus** is formed by lines mainly used for synchronisation between the elements of the computer. The minimal implementation includes the read and write lines. Read line (#RD) is the information that other elements use to indicate that the processor wants to read data from the unit. In such a situation, the element, e.g. memory, puts the data from the addressed cell on the data bus. Active write signal (#WR) informs the element that the data which is present on the data bus should be stored at the specified address.
 The control bus can also include other signals specific to the system, e.g., interrupt signals, DMA control lines, clock pulses, signals distinguishing memory and peripheral access, signals activating selected modules, and others. The control bus can also include other signals specific to the system, e.g., interrupt signals, DMA control lines, clock pulses, signals distinguishing memory and peripheral access, signals activating selected modules, and others.
 +
 +<note info>
 +The "#" symbol before a signal name means that the active signal on the line is a LOW state, while idle is a HIGH state.
 +</note>
  
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