Octek DRAGON EISA 486, Manual, Page: 13 / 137

GENERAL FEATURES
__________________________________
PROCESSOR
The 80486 microprocessor is the state-of-art
microprocessor which merges many innovative features
on a single chip for advanced applications and operating
systems. Fabricating with the l um process, this CPU
consists of more than one million transistors. With such
high density, this CPU incorporates as many as new
features to make itself the most powerful
microprocessor.
80486 is a 32-bit microprocessor with 32-bit
external data bus and 32-bit external address bus. It not
only contain a central processing but also integrates a
numeric processor and a four-way set associate cache
memory. It is fully binary compatible with 80386 and
80387. All existing software for PC XT/AT can be used on
the DRAGON EISA. However, due to the new internal
architecture, the performance of 80486 is two or four
times of 80386.
The overall performance of computer system can
be improved by cache memory. Nevertheless, if the
cache memory is separated from CPU, CPU still needs to
fetch code and data through external bus. That means
the data transfer rate should not be too fast so that the
external device are able to keep pace with the CPU. In
80486, the cache controller and cache memory are
integrated into the chip. Most of the operations can be
carried out inside the CPU, which reduces the bus
operations on external data and address bus and thus
speeds up the internal execution.