			   Intel 80386



- Full 32 bit processor

     32 bit non-multiplexed address bus

     32 bit data bus

     32 bit internal bus

     8 general purpose 32-bit registers



- Integrated Memroy Management Unit

     4 gigabyte physical address space

     64 terabyte virtual memory support

     4	gigabyte maximum segment size

     Optional On-chip Paging (a la VAX, 386 is THE UNIX machine)

     Full superset of 80286 MMU and fully compatible



- Object Code Compatible with All 8086 Family Processors



- Virtual 8086 Mode

     Allows running multiple 8086 tasks (read PC software) in a

     protected and paged system



- Hardware Debugging Support

     4 32 bit breakpoint registers allow breakpoints to be set

	  in code or data



- Optimized for Performance

     Pipelined instruction execution

     On-chip address translation caches

     16 MHZ clock

     32 megabytes/sec bus bandwidth

     Sustained through-put between 3 and 4 million instructions

	  per second.



- Complete Development Support

     All existing 8086 and 80286 tools can be used

     C386, PL/M386, ASM386+system generation tools available

	  from Intel now.

     Debuggers: PSCOPE, ICE-386



- CHMOS III Technology

     1.5 micron feature size

     280,000 transistors





The  386  is a full 32 bit processor optimized	for  multitasking

operating systems. The device comes in a 132 Pin Grid Array

package and draws approx. 400 MA. The device is fully compatible

with the 8086 and 80286 processors at an object code level and

will run the same software. Intel has an AT which has been

modified  to  use  the	386  running  PCDOS  and  other  software

including Flight Simulator. Intel also has XENIX-286 and RMX-286

running on the Intel System 310 supermicro. Intel has Multibus I

cards with 32 bit memory which run at 16 MHZ 0 wait states and

a Multibus II card will be available at the first of the year.



The 386 architecture should be able to please everyone.

Those educated in computer architecture will agree that



segmentation is a good architecture (especially for

multi-tasking systems). It is really the 64k byte segments

that bothers programmers. Segmentation is still the basis for the

386 architecture but 64k segment sizes are no longer. Segments

can now be up to 4 gigabytes in size (the physical address space).

This should especially please those "flat" (read Motorola)

architecture fans because if you point the segment registers at

00000000H (the beginning of memory) and set their size to

4 gigbytes (about ten instructions at initialization time) you

now have a flat address space. Segment offsets can now be 32bits

so you can address the whole 4 gigbytes and never have to think

about segment registers.



Register   orthogonality  has also been addressed (no pun

intended). All eight registers can be used in all addressing

modes for all things. All registers are a full 32 bits but can

be  accessed  as  16  and 8  bit  registers  also.  The  8086/286

registers are a subset. All conditionaljumps are now variable

length and can have 8, 16, or 32 bit offsets. Numerous new

instructions have been added especially in the bit manipulation

area. These include bit set/clear/test/complement, bit fiels

insert/extract, find first set bit, byte set on test,

integer conversions (sign extend, zero extend), 32 bit mul. and

divides. New addressing modes and data segment registers have been

added and many old instructions have been enhanced. In spite of

all these changes, the 80386 remains fully upward compatible with

its predecessors.



Performance -



		3x - 8 MHZ 80286 for 16 bit code

		4.7x - 8 MHZ 80286 for 32 bit code

		17x - IBM PC



		.56 to 2.4 microsecond 32 bit multiply

		2.4 microsecond 32 bit divide

		17 microsecond task switch (saves context of whole machine)



Availability -



Intel is sampling 16 MHZ 80386's now. The current stepping of the

part has some errata but nothing show stopping. All the current

8086/286 runs on the 386 now so there is plenty of software. In

addition Intel has ASM386, C386, and PL/M386 to support the

complete 386 architecture available now to run on XENIX286

machines.



Hope this clears up some of the rumors circulating about the

386.



				Ron Curry

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