 An AMD 80386DX-40 in a 132-pinPQFP, soldered onboard | |
| General information | |
|---|---|
| Launched | 1991 |
| Marketed by | AMD |
| Designed by | AMD |
| Common manufacturer |
|
| Product code | 23936 |
| Performance | |
| Max.CPUclock rate | 20 MHz to 40 MHz |
| FSB speeds | 20 MHz to 40 MHz |
| Cache | |
| L1cache | Motherboard dependent |
| L2 cache | none |
| Architecture and classification | |
| Application | Desktop, Embedded (DE/SE-Models) |
| Technology node | 1.5 μm to 0.8 μm |
| Microarchitecture | 80386 |
| Instruction set | x86 (IA-32) |
| Physical specifications | |
| Cores |
|
| Packages | |
| History | |
| Predecessor | Am286 |
| Successor | Am486 |
TheAm386CPU is a100%-compatible clone of theIntel 80386 design released byAMD in March 1991. It sold millions of units, positioning AMD as a legitimate competitor toIntel, rather than being merely a second source forx86 CPUs (then termed8086-family).[1]
While the AM386 CPU was essentially ready to be released prior to 1991, Intel kept it tied up in court.[2] Intel learned of the Am386 when both companies hired employees with the same name who coincidentally stayed at the same hotel, which accidentally forwarded a package for AMD to Intel's employee.[3] AMD had previously been a second-source manufacturer of Intel'sIntel 8086,Intel 80186 andIntel 80286 designs, and AMD's interpretation of the contract, made up in 1982, was that it covered all derivatives of them. Intel, however, claimed that the contract only covered the 80286 and prior processors and forbade AMD the right to manufacture 80386 CPUs in 1987. After a few years in the courtrooms, AMD finally won the case and the right to sell their Am386 in March 1991.[4] This also paved the way for competition in the80386-compatible32-bit CPU market and so lowered the cost of owning a PC.[1]
While Intel's 386 CPUs had topped out at 33MHz in 1989, AMD introduced 40 MHz versions of both its 386DX and 386SX out of the gate, extending the lifespan of the architecture. In the following two years the AMD 386DX-40 saw popularity with small manufacturers of PC clones and with budget-minded computer enthusiasts because it offered near-80486 performance at a much lower price than an actual 486.[5] Generally the 386DX-40 performs nearly on par with a 25 MHz 486 due to the 486 needing fewer clock cycles per instruction, thanks to its tighterpipelining (more overlapping of internal processing) in combination with an on-chipCPU cache. However, its32-bit 40 MHzdata bus gave the 386DX-40 comparatively good memory and I/O performance.[6]
| Model number | Frequency | FSB | Voltage | Power | Socket |
|---|---|---|---|---|---|
| AMD Am386DX/DXL-20 | 20 MHz | 5 V | 1.05 Watt | 132-pinCPGA | |
| 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-pinPQFP | |||
| AMD Am386DXLV-25 | 25 MHz | 3-5 V | 445 mW (at 3.3V) | 132-pin PQFP,[8] 132-pin PGA[7] | |
| AMD Am386DXLV-33 | 33 MHz | 5 V | 1.65 Watt | ||
| Model number | Frequency | FSB | Voltage | Power | Socket | Release date |
|---|---|---|---|---|---|---|
| AMD Am386DE-25KC | 25 MHz | 3-5 V | 0.32-1.05 Watt | 132-pinPQFP | 1994[9] | |
| AMD Am386DE-33KC | 33 MHz | 5 V | 1.05-1.35 Watt | |||
| AMD Am386DE-33GC | 132-pin CPGA | |||||
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.[10] 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.[10]
--(386-CPU).png)
| Model number | Frequency | FSB | Voltage | Power | Socket | Release date |
|---|---|---|---|---|---|---|
| AMD Am386SX/SXL-20 | 20 MHz | 5 V | 1.68/0.85 Watt | 100-pinPQFP | 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 | |||
| AMD Am386SXLV-20 | 20 MHz | 3-5V | 100-pin PQFP[8] | October 1991[7] | ||
| AMD Am386SXLV-25 | 25 MHz | 412 mW (at 3.3V)[7] | ||||
| Model number | Frequency | FSB | Voltage | Socket | Release date |
|---|---|---|---|---|---|
| AMD Am386SE-25KC | 25 MHz | 3-5 V | 100-pinPQFP | 1994[9] | |
| AMD Am386SE-25KI | |||||
| AMD Am386SE-25VC | 100-pinTQFP | ||||
| AMD Am386SE-25VI | |||||
| AMD Am386SE-33KC | 33 MHz | 5 V | 100-pin PQFP | ||
The Am386 processor core has been used in some embedded processors. In October 1993, AMD introduced the Am386SC processor, which integrated an Am386SXLV CPU core with a collection of PC/AT-compatible peripherals.[13] This processor, marketed as "Élan SC300" and "Élan SC310", was the first in AMD's Élan series of SoCs. In 1994, AMD announced the Am386EM microcontroller, which integrated an Am386 CPU core with a collection of80186-compatible peripherals rather than PC/AT peripherials.[14][15] This chip does not, however, appear to have been released,[16] although a datasheet exists.[17]
Floating point performance of the Am386 could be boosted with the addition of a80387DX or80387SXcoprocessor, although performance would still not approach that of the on-chipFPU of the 486DX. This made the Am386DX a suboptimal choice forscientific applications andCAD using floating point intensive calculations. However, both were niche markets in the early 1990s and the chip sold well, first as a mid-range contender, and then as a budget chip. Althoughmotherboards using the older 386 CPUs often had limited memory expansion possibilities and therefore struggled underWindows 95's memory requirements, boards using the Am386 were sold well into the mid-1990s; at the end as budget motherboards for those who were only interested in runningMS-DOS orWindows 3.1x applications.The Am386 and its low-power successors were also popular choices forembedded systems, for a much longer period than their life span asPC processors.
