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INTRODUCTION
Reconfigurable computing technology is the ability to modify a computer system's
hardware architecture in real time. Although originally proposed in the late 1960s
by a researcher at UCLA, reconfigurable computing is a relatively new field of
study. The decades long delay had mostly to do with a lack of acceptable reconfigurable
hardware. Interest in this field was first triggered- off late in 2002 when a
small Silicon Valley start up called Quick Silver Technologies announced what
it called the Adaptive Computing Machine(ACM), a new class of digital integrated
circuit that can be embedded directly into a mobile device and will enable hardware
to be programmed almost as if it were a piece of software, For example, take 3
common applications that the average mobile phone performs seamlessly: search
for a local cellphone; verify whether the number represents an authorized user
then make the connection. Today the 3 operations are performed by 3 different
chips inside the handset. With the new adaptive technology, a single chip can
be reconfigured by a software instruction to assume different hardware functions
and to perform all 3 applications one after the another
The earliest
reconfigurable computing systems predate even digital computers. Before digital
logic scientific and engineering computations were done on programmable analog
computers: big banks of op amps, comparators, multipliers and passive components
interconnected via a plug board and patch cords. By connecting components together,
the very clever user could implement a network whose node obeyed a set of differential
equation solver, capable of deployment- time reconfigurability. Toward the end
of its era, the analog computer was combined with relay banks, and later with
digital computers, to form hybrids. These machines could reconfigure themselves
between execution sequences, providing an early form of yet another category of
configurability. Some hybrid computer programmers become experts at juggling configurations
while holding data in sample and to extend the range of these systems
The first moves toward really fluid reconfigurability came with the advent of
embeddable digital computers. With the characteristics of a system defined by
software in RAM, nothing could be simpler. Changing the operation of the system
at installation, in response to changing data or even on the fly, is the matter
of loading a different application. Variants on this theme included tightly coupled
networks of computers in which the network topology could adapt to changing data
flows, and even computers that could change their instruction sets in response
to changing application demands.
But the first explorations into what
most people today mean by the term reconfigurable computing came after the development
of large SRAM- based FPGAs. The devices provided a fabric of logic cells and interconnects
that could be altered- albeit with some difficulty - to create just about any
logic netlist that would fit into the chip. Researches quickly seized upon the
parts and began experimenting with deployment tie reconfiguration creating a hardwired
digital network designed for a specific algorithm.
Experiments with reconfigurability
in FPGAs identified two promising advantages: reduction of size or power consumption
of the hardware, and increases in performance. Often the two types of advantages
came together, rather than separately. The advantages, it turned out, came with
only few quite specific techniques. One of these was simple: reuse of hardware.
If it is organize a system in such a way that it has several distinct, non overlappimg
operating modes, then you can save hardware by configuring a programmable fabric
to execute in one mode, stopping, then configuring it to operate in another mode
A number of companies are currently working in this area. Most of the big
players in the conventional DSP/ASIC area -Texas ,IBM, Motorola, Intel- are known
to be working overtime to come up with reconfigurable designs of their own. RECONFIGURABLE
COMPUTING SYSTEMS
Current computers are fixed hardware systems based
upon microprocessors. As powerful as the microprocessor is, it must handle far
more functions than just the application at hand. With each new generation of
microprocessors, the applications performance increases only incrementally.In
many cases the application must be rewritten to achieve this incremental performance
enhancement. Traditional fixed hardware may be classified into three categories:
Logic(Gate Arrays, PALS etc.), Embedded control (controllers eg ASICs & Custom
VLSI Devices) and Computers(Microprocessors eg x 86, 68000, Power PC). Reconfigurable
Computing Systems are those computing platforms whose architecture can be modified
by the software to suit the application at hand. To get the maximum through put,
an algorithm must be placed in hardware ( eg. ASIC, DSP, etc) Dramatic performance
gains are obtained through the 'hardwiring' of the algorithm. In a recofigurable
computing system, the "Hardwaring takes place on a function by function basis
as the application executes
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