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In computing, an input–output memory management unit (IOMMU) is a memory management unit (MMU) connecting a direct-memory-access–capable (DMA-capable) I/O bus to the main memory. Like a traditional MMU, which translates CPU -visible virtual addresses to physical addresses , the IOMMU maps device-visible virtual addresses (also called device ...
The 11/45 architecture expanded to allow 4 MB of physical memory segregated onto a private memory bus, 2 KB of cache memory, and much faster I/O devices connected via the Massbus. PDP–11/34 (1976 [ 15 ] ) and PDP–11/04 (1975 [ 15 ] ) – Cost-reduced follow-on products to the 11/35 and 11/05; the PDP–11/34 concept was created by Bob ...
The simplest system bus has completely separate input data lines, output data lines, and address lines. To reduce cost, most microcomputers have a bidirectional data bus, re-using the same wires for input and output at different times. [20] Some processors use a dedicated wire for each bit of the address bus, data bus, and the control bus.
The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. [2] [3] The BIOS firmware was originally proprietary to the IBM PC; it was reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. The interface of that original system serves as a de facto standard.
The input/output instructions all start with bits 0 through 2 being set to 1 (decimal value 7), bits 3 through 9 containing a device number, and 10 through 12 the instruction opcode. [ 22 ] In both formats, bits 13 through 35 are used to form the "effective address", E. Bits 18 through 35 contain a numerical constant address, Y.
A 68451 MMU, which could be used with the Motorola 68010. A memory management unit (MMU), sometimes called paged memory management unit (PMMU), [1] is a computer hardware unit that examines all memory references on the memory bus, translating these requests, known as virtual memory addresses, into physical addresses in main memory.
Parallel I/O, in the context of a computer, means the performance of multiple input/output operations at the same time, for instance simultaneously outputs to storage devices and display devices. [1] It is a fundamental feature of operating systems .
Device interfaces where one bus transfers data via another will be limited to the throughput of the slowest interface, at best. For instance, SATA revision 3.0 (6 Gbit/s) controllers on one PCI Express 2.0 (5 Gbit/s) channel will be limited to the 5 Gbit/s rate and have to employ more channels to get around this problem.