Signal in the system bus of an x86-based computer system
The high memory area is only available in real mode on 80286 processors if the A20 gate is enabled.
The A20, or address line 20, is one of the electrical lines that make up the system bus of an x86-based computer system. The A20 line in particular is used to transmit the 21st bit on the address bus.
A microprocessor typically has a number of address lines equal to the base-two logarithm of the number of words in its physical address space. For example, a processor with 4 GB of byte-addressable physical space requires 32 lines (log2(4 GB) = log2(232 B) = 32), which are named A0 through A31. The lines are named after the zero-based number of the bit in the address that they are transmitting. The least significant bit is first and is therefore numbered bit 0 and signaled on line A0. A20 transmits bit 20 (the 21st bit) and becomes active once addresses reach 1 MB, or 220.
The A20, or address line 20, is one of the electrical lines that make up the system bus of an x86-based computer system. The A20line in particular is...
20, a predecessor of the Junkers A 35 aircraft A20 cell line, a cell line. A20line, an address line on the system bus of x86 processors University of...
disable (force to zero) the A20 address line, between the A20 pin on the 80286 and the system bus; this is known as Gate-A20 (the A20 gate), and it is still...
compatibility with the PC and XT behavior, the AT included an A20line gate (Gate A20) that made memory addresses on the AT wrap around to low memory...
segment_part × 16 + offset, if the address lineA20 is enabled, or (segment_part × 16 + offset) mod 220, if A20 is off.[clarification needed] Every segment...
laptop lid switch (received from hall sensor)) Controlling access to the A20line Thermal measurement (CPU, GPU, Motherboard) and response including fan...
Dance Dance Revolution A20 (pronounced Ace Two Oh) is a music video game, the 17th installment of the Dance Dance Revolution arcade series in Japan (the...
logic gate which could disconnect the microprocessor's 21st addressing line, A20, from the rest of the motherboard. This gate could be controlled, initially...
are merely strongly discouraged. PC 2001 removes compatibility for the A20line: "If A20M# generation logic is still present in the system, this logic...
clock doubling. Part of the problem was that on most 386 motherboards, the A20line was controlled entirely by the motherboard with the CPU being unaware,...
legacy wires replaced include the INTR, A20M, and SMI legacy signals. A20line INTR System Management Mode Safranek, Robert J.; Moravan, Michelle J. (November...
LOADALL Global EMM Import Specification (GEMMIS) x86 assembly language A20line Salihun, Darmawan (2013-09-16). "System Address Map Initialization in x86/x64...
hardware external to the processor, by gating off the 21st address line, the A20line. The IBM PC AT provided the hardware to do this (for full backward...
AMI continued to focus on OEM and ODM business and technology. Its product line includes or has previously included AMIBIOS (a BIOS), Aptio (a successor...
A20 cells, also called ATCC TIB-208, is a cell line originally derived from B-cell lymphoma in an old BALB/c mouse. AT20 cells are BALB/c lymphoma cells...
process. In XOSL-OW these stability issues have been solved by an improved A20line switching algorithm and flushing the keyboard buffer before the XOSL boot...
Windows NT and OS/2, and those systems most certainly cannot run with the A20line disabled. How does that work then? […] Rather than chopping off address...
to establish a joint venture to market (and hopefully sell) the A20 in Europe. The A20 was subsequently entered in the competition to replace the Royal...
February 15, 2018. Fujifilm X-A20: Similar specifications to X-A10 with an addition of a touch sensitive LCD display. The X-A20 was limited to primarily Asian...
Asakusa Line (都営地下鉄浅草線, Toei Chikatetsu Asakusa-sen) is a subway line in Tokyo, Japan, operated by the municipal subway operator Toei Subway. The line runs...
and LT models were introduced in the US for the 1974 model year. The top-line GT included a 5-speed W-50 manual transmission, rocker panel GT stripes and...
The RijnGouweLijn (English: The Rhine-Gouwe Line), or RGL, was a proposed light rail project in South Holland, Netherlands, that used some new tracks and...
light rail". The Oregonian. p. A20. Stewart, Bill (June 19, 1998). "Portland officially maps a South–North rail line". The Oregonian. p. B3. Oliver,...
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