Am386

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Am386
Am286
SuccessorAm486

The Am386 CPU is a 100%-compatible clone of the Intel 80386 design released by AMD in March 1991. It sold millions of units, positioning AMD as a legitimate competitor to Intel, rather than being merely a second source for x86 CPUs (then termed 8086-family).[1]

History and design

Wafer of an Am386 processor with Intel copyright notice.
Die of AMD Am386DX.

While the AM386 CPU was essentially ready to be released prior to 1991, Intel kept it tied up in court.

32-bit CPU market and so lowered the cost of owning a PC.[1]

While Intel's 386 CPUs had topped out at 33

32-bit 40 MHz data bus gave the 386DX-40 comparatively good memory and I/O performance.[6]

  • An Am386DX-25
    An Am386DX-25
  • The Am386DE-33 is an embedded version of the Am386DX-33
    The Am386DE-33 is an embedded version of the Am386DX-33
  • A PGA Am386DX-40
    A PGA Am386DX-40
  • A PQFP Am386DX-40 on a 132-pin PGA adapter
    A PQFP Am386DX-40 on a 132-pin PGA adapter
  • AMD Am386DE Block Diagram There is not a Paging Unit like a DX CPU
    AMD Am386DE Block Diagram There is not a Paging Unit like a DX CPU
  • A scan of an AMD Am386™DX-40 mounted on a PGA adapter.
    A scan of an AMD Am386™DX-40 mounted on a PGA adapter.

Am386DX data

  • 32-bit data bus, can select between either a 32-bit bus or a 16-bit bus by use of the BS16 input
  • 32-bit physical address space, 4 Gbyte physical memory address space
  • fetches code in four-byte units
  • released in March 1991
The various models of the Am386DX, data from[1][2]
Model number Frequency FSB Voltage
Power
 Socket
AMD Am386DX/DXL-20 20 MHz 5 V 1.05 Watt 132-pin
CPGA
AMD Am386DX/DXL-25 25 MHz 1.31 Watt
AMD Am386DX/DXL-33 33 MHz 1.73 Watt
AMD Am386DX/DXL-40 40 MHz 2.10 Watt
AMD Am386DX-40 3.03 Watt 132-pin
PQFP

Am386DE data

  • 32-bit data bus, can select between either a 32-bit bus or a 16-bit bus by use of the BS16 input
  • 32-bit physical address space, 4 Gbyte physical memory address space
  • fetches code in four-byte units
  • no paging unit
The various models of the Am386DE, data from[1][2]
Model number Frequency FSB Voltage
Power
 Socket Release date
AMD Am386DE-25KC 25 MHz 3-5 V 0.32-1.05 Watt 132-pin
PQFP
 ?
AMD Am386DE-33KC 33 MHz 5 V 1.05-1.35 Watt
AMD Am386DE-33GC 132-pin CPGA

AM386 SX

In 1991 AMD also introduced advanced versions of the 386SX processor – again not as a second source production of the Intel chip, but as a reverse engineered pin compatible version. In fact, it was AMD's first entry in the x86 market other than as a second source for Intel.[7] AMD 386SX processors were available at higher clock speeds at the time they were introduced and still cheaper than the Intel 386SX. Produced in 0.8 μm technology and using a static core, their clock speed could be dropped down to 0 MHz, consuming just some mWatts. Power consumption was up to 35% lower than with Intel's design and even lower than the 386SL's, making the AMD 386SX the ideal chip for both desktop and mobile computers. The SXL versions featured advanced power management functions and used even less power.[7]

  • An Am386SX-25
    An Am386SX-25
  • An Am386SX-33
    An Am386SX-33
  • An Am386SX-40
    An Am386SX-40

Am386SX data

  • 16-bit data bus, no bus sizing option
  • 24-bit physical address space, 16 Mbyte physical memory address space
  • prefetch unit reads two bytes as one unit (like the
    80286
    ).
The various models of the Am386SX, data from[2][7][8]
Model number Frequency FSB Voltage
Power
 Socket Release date
AMD Am386SX/SXL-20 20 MHz 5 V 1.68/0.85 Watt 100-pin
PQFP
 1991
AMD Am386SX/SXL-25 25 MHz 1.84/1.05 Watt 29 April 1991
AMD Am386SX/SXL-33 33 MHz 1.35 Watt 1992
AMD Am386SX-40 40 MHz 1.55 Watt 1991

80387 coprocessor

Windows 3.1x
applications. The Am386 and its low-power successors were also popular choices for embedded systems, for a much longer period than their life span as PC processors.

  • An IIT 387SX-25 Coprocessor
    An IIT 387SX-25 Coprocessor
  • A Cyrix FasMath 387DX-33 Coprocessor
    A Cyrix FasMath 387DX-33 Coprocessor
  • An ULSI 387SX-40 Coprocessor
    An ULSI 387SX-40 Coprocessor

References

  1. ^ a b c d "The AMD Am386 DX Processor". cpu-collection.de. 2011. Retrieved 12 November 2011.
  2. ^ a b c d Shvets, Gennadiy (5 November 2011). "AMD 80386 microprocessor". CPU-World. Retrieved 29 November 2011.
  3. ISBN 978-0-06-221968-8
    .
  4. ^ Pollack, Andrew (2 March 1991). "Intel Loses Trademark Decision". The New York Times.
  5. ^ "386DX-40 and competitors". the red hill cpu guide. 2011. Retrieved 12 November 2011.
  6. ^ Linderholm, Owen; Miller, Dan (1 December 1992). "486SX-25s vs. 386DX-40s: the upstart fights back. (evaluations of 30 microcomputers based on Intel Corp.'s 80486SX-25, 80386DX-40 microprocessors) (Hardware Review) (Systems: 486SX-25 vs. 386-40) (Evaluation)". Archived from the original on 1 January 2014. Retrieved 12 November 2011.
  7. ^ a b c "The AMD Am386 SX Processor". cpu-collection.de. 2011. Retrieved 30 November 2011.
  8. ^ [1] Archived 2016-03-04 at the Wayback Machine, AMD Datasheet no 15022.

External links

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