???? Has anyone replaced the 80286 with NEC's V40 (6300+) ?????

[Paul Cohen]

Tony Stieber	astieber at csd4.milw.wisc.edu states:

> The NEC Microcomputer Products Databook 1987 describes the V40 as an 8/16
> bit microprocessor, the 80286 is a full 16 bits.  The V50 is described as
> a V40 but with a 16 bit data buss.  These two V-series chips seem to
> be clones on the Intel 8018x processors with 8080 emulation.  The V60 chip
> appears to be the 80386.  Apparently NEC never got a license to fabricate
> the 80286, in fact I think Harris was to the only company to second source
> that chip.

These comments demonstrate that there is some confusion about the
V-series parts that I will try to correct.

The V20 and V30 are faster, functional extensions of the 8088 and 8086
processors.  The V40 and V50 processors consist of the V20 and V30
processors integrated with a family of peripherals so as to be
functional extensions of the 80188 and 80186 processors.  The functional
extensions do include 8080 emulation in each case.  

For several years the sale of the NEC V-series parts have been hindered 
by a law suit brought against NEC by Intel who claimed microcode 
copyright infringement by NEC.  The courts have recently found, in NEC's
favor, that although microcode can be copyrighted, Intel DID NOT HAVE a 
valid copyright on the 8086 microcode and even if they did, NEC DID NOT 
COPY the microcode of the 8086.

NEC's microcode-less V33 serves a market that is somewhat similar to the 
80286, but it is not compatible with the 80286.  It is upward compatible
to the 8086 and it supports memory mapping but in a different manner
than does the 80286: it directly supports LIM spec 4.0 with internal
hardware.  Benchmarks show the performance of the V33 to be higher than
the 80386SX at the same clock rate.

NEC's V70 and V80 are full 32-bit microprocessors with on-chip floating
point and on-chip MMU.  The V80 also has an on-chip cache.  The V60 is a
16-bit external bus version of this same architecture.  The V60, V70 and 
V80 each have 32 32-bit general purpose registers, they support a 4
G-byte paged virtual address space.  The V60 and V70 offer an emulation 
mode to execute 8086 code but this is the closest these processors get to 
the architecture of any Intel processor.  In particular, the V60 is not 
similar to the 80386 or in fact any processor manufactured by Intel.  
NEC does not offer any processor compatible with Intel's 80286, 80386 or 
80486.