| slovo | definícia |
intel 486
(foldoc) | Intel 486
486
486DX
80486
i486
Intel 80486
(Or "i486", "iAPX 80486", and "Intel DX4" but
usually just "486"). A range of Intel CISC
microprocessors which is part of the Intel 80x86 family of
processors.
The 486s are very similar to their immediate predecessor, the
Intel 80386DX. The main differences are that the 486 has an
optimised instruction set, has an on-chip unified
instruction and data cache, an optional on-chip
floating-point unit (FPU), and an enhanced {bus interface
unit}. These improvements yield a rough doubling in
performance over an Intel 80386 at the same clock rate.
There are several suffixes and variants including:
Intel 486SX - a 486DX with a faulty FPU that has been
disabled in the factory.
Intel 486DX - 486SX with a working FPU.
486DX-2 - runs at twice the external clock rate.
486SX-2 - runs at twice the external clock rate.
486SL - 486DX with power conservation circuitry.
486SL-NM - 486SX with power conservation circuitry; SL
enhanced suffix, denotes a 486 with special power conservation
circuitry similar to that in the 486SL processors.
487 - 486DX with a slightly different pinout for use in 486SX
systems.
OverDrive - 486DX-2 with a slightly different pinout for use
in 486SX systems.
RapidCAD - 486DX in a special package with a companion FPU
dummy package for use in Intel 80386 systems.
Intel DX4, Cyrix Cy486SLC.
External clock rates include 16MHz, 20MHz, 25MHz, 33MHz,
40MHz, although 16Mhz is rare now, and the 20MHz processors
are often clock doubled.
The 486 processor has been licensed or reverse engineered by
other companies such as IBM, AMD, Cyrix, and {Chips &
Technologies}. Some are almost exact duplicates in
specications and performance, some aren't.
The successor to the 486 is the Pentium.
(1995-02-21)
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| | podobné slovo | definícia |
intel 486
(foldoc) | Intel 486
486
486DX
80486
i486
Intel 80486
(Or "i486", "iAPX 80486", and "Intel DX4" but
usually just "486"). A range of Intel CISC
microprocessors which is part of the Intel 80x86 family of
processors.
The 486s are very similar to their immediate predecessor, the
Intel 80386DX. The main differences are that the 486 has an
optimised instruction set, has an on-chip unified
instruction and data cache, an optional on-chip
floating-point unit (FPU), and an enhanced {bus interface
unit}. These improvements yield a rough doubling in
performance over an Intel 80386 at the same clock rate.
There are several suffixes and variants including:
Intel 486SX - a 486DX with a faulty FPU that has been
disabled in the factory.
Intel 486DX - 486SX with a working FPU.
486DX-2 - runs at twice the external clock rate.
486SX-2 - runs at twice the external clock rate.
486SL - 486DX with power conservation circuitry.
486SL-NM - 486SX with power conservation circuitry; SL
enhanced suffix, denotes a 486 with special power conservation
circuitry similar to that in the 486SL processors.
487 - 486DX with a slightly different pinout for use in 486SX
systems.
OverDrive - 486DX-2 with a slightly different pinout for use
in 486SX systems.
RapidCAD - 486DX in a special package with a companion FPU
dummy package for use in Intel 80386 systems.
Intel DX4, Cyrix Cy486SLC.
External clock rates include 16MHz, 20MHz, 25MHz, 33MHz,
40MHz, although 16Mhz is rare now, and the 20MHz processors
are often clock doubled.
The 486 processor has been licensed or reverse engineered by
other companies such as IBM, AMD, Cyrix, and {Chips &
Technologies}. Some are almost exact duplicates in
specications and performance, some aren't.
The successor to the 486 is the Pentium.
(1995-02-21)
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intel 486dx
(foldoc) | Intel 486DX
One of Intel's Intel 486 family of
microprocessors (one of the last before the Pentium). The
486DX has a working built-in floating point unit (FPU). The
Intel 486SX is effectively a DX with the FPU disabled. The
DX has a pin to select the external data bus width (16 or
32).
The Intel 487SX is a 486DX with a 486SX pinout.
(1995-05-09)
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intel 486sx
(foldoc) | Intel 486SX
486SX
An Intel 486DX microprocessor with its
floating-point unit disconnected. All 486SX chips were
fabricated with FPUs. If testing showed that the CPU was OK
but the FPU was defective, the FPU's power and bus connections
were destroyed with a laser and the chip was sold cheaper as
an SX, if the FPU worked it was sold as a DX.
[Was this true of all 486SX chips?]
Some systems, e.g. Aopen 486SX, allowed a DX to be plugged
into an expansion socket. A board jumper would disable the SX
which was hard to remove because it was surface mounted.
Some SX chips only had a 16-bit wide external data bus. The
DX has a pin to select the data bus width (16 or 32). On the
smaller SX, that line is hard-wired to 16 inside the
package. This is similar to the 286 SX, which was a 16-bit
processor with an 8-bit external data bus.
The Jargon File claimed that the SX was deliberately
disabled crippleware. The German computer magazine, "c't",
made this same theory the basis of an April Fools Joke.
They claimed that if one drilled a hole of a specified
diameter through the right point on a SX chip, this would
brake the circuit that disables the FPU. Some people actually
tried (and then bought themselves new processors).
(1997-02-14)
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