Intel 80860 (i860) is a 32-bit microprocessor with 64-bit external data bus.
The microprocessor included several features that greatly improved
processor performance when running properly optimized code:
- The CPU could execute the majority of floating-point instructions
either in pipelined mode or in scalar mode. In scalar mode the
instructions executed one after another, which took from 3 to 4 clock
cycles per instruction. In pipelined mode instruction execution was
broken into three or four stages, and the CPU could execute different
stages of different instructions at the same time. As a result one
floating-point unit could provide new result every clock cycle.
- Two floating point execution units (FP added and FP multiplier)
could work in parallel, that is theoretically the CPU could provide
two results every cycle.
- Core execution Unit also worked in parallel with FP units.
In addition to that the processor could load and execute two
instructions at the same time - one integer instruction and one
floating point instruction. Also, certain floating-point instructions
performed more than one operation, using both FP execution units
simultaneously. Overall processor performance was highly dependent on
how well the code is optimized.
As a result the i860 was much more popular in areas where the code
doesn't change often or doesn't change at all - as an embedded or
graphics processor, and had very limited use as a CPU (with the
exception of parallel computer systems).
Intel 80860XP was an improved version of 80860XR. It had larger and
better L1 code and data caches, and multiprocessor support.
|
