Am5x86
AMD-X5-133ADW
Developer	AMD
Manufacturer	AMD
Type	Microprocessors
Introduction	1995 (announced) November 6, 1995 (launch)
Architecture	Enhanced Am486
ISA	IA-32
µarch	80486
Word size	32 bit 4 octets 8 nibbles
Process	350 nm 0.35 μm 3.5e-4 mm
Technology	CMOS
Clock	133 MHz-150 MHz
Package	CPGA-168, SQFP-208
Socket	Socket 1, Socket 2, Socket 3
Succession
←	→
Am486	K5

Am5_x86 was a family of highest performance 486-based microprocessors introduced by AMD in 1995. These processors came with all the features of the Enhanced Am486s but had the highest clock speed available. These chips, which ended up performing comparable and on occasion better than the Pentium-75, became the de-facto upgrade for users with existing 486-based systems. This family solidified AMD position as the official Intel competition.

History

In 1995 AMD was busy working on their first home-grown x86-compatible microarchitecture, K5. Has a sort of a stopgap between the Am486 and the yet-to-be-released K5-based processors, AMD released the Am5x86 family. The name came about due to competitors selling 5th generation-based x86 processors (e.g. Cyrix 5x86) - people were more likely to buy a system with "5" vs "4". AMD took this opportunity to utilize their latest technology and release a final, highest clocked 486 chip for much lower price than their competitor's latest chips. This is very similar to what they had done with their highly successful 40 MHz version of their Am386 family. Later, strong sales of Am5x86 played a crucial role in keeping AMD's profitability while their K5 microarchitecture was experiencing severe delays. AMD continued to sell Am5x86 chips for personal computers until 1999 and for embedded systems well into the 2000s.

Architecture

Contrary to its namesake, the 5x86 was not a "5th-generation x86". Architecturally, the 5x86 is identical to the Enhanced Am486s which included various system and power management features (e.g. SMM & Stop-clock control). Additionally the 5x86 came with the larger 16 KB write-back L1$. The processors were manufactured on AMD's newly upgraded 350 nm process which is what allowed AMD to clock it as high and compete with Intel's low-end Pentiums. AMD had to clock the 5x86 at much higher frequency in order to compensate for its inefficiencies and deliver performance comparable to the Pentium-75. The clock multiplier was set to x4 (e.g. bus speed of 33 MHz would have a core frequency of 133 MHz). Essentially, one can think of the 5x86 as a "Am486DX5-133". In fact, AMD simply sold the Am5x86 clocked under 133 MHz as Enhanced Am486 instead.

Being backwards compatible, the 5x86 could go in the older Socket 1, Socket 2, and Socket 3. However Socket 1/2 both required a replacement voltage regulator as the chips needed 3.45 V to operate. Depending on the motherboard, it either had a manual jumper one has to set or an autodetect version, voltage must be set to 3.45 (± 0.15 tolerance). Likewise the input clock must be set to 33 MHz with a jumper set to quadrupled clock (note that because there is no such provision in the socket, setting the "clock-doubled" setting should cause the CLKMUL pin to be driven high allowing the processor to operate at x4 multiplier). While set to 133 MHz, many in the hobbyist community have reported to have had it overclocked to 160 MHz which would put it at performance similar to the Pentium-90. The later versions had higher package temperature rating, making them easier to be overclocked.

Die Shot

Members

AMD released a 133 MHz version with a multiplier of x4 and a 150 MHz version with a multiplier for x3. Various publications by AMD (including their own BIOS manual) mentioned a 160 MHz version with a multiplier of x4, however that processor was never actually released.

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Am486DX Processors
Model	Launched	Process	Freq	Bus	Max Mem	Package
AM486DX5-133V16BGC	1997	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AM486DX5-133V16BHC	1997	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AM486DX5-133W16BGC	1997	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AM486DX5-133W16BHC	1997	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133ADW	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133ADY	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133ADZ	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SDW	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SDY	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SDZ	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SFW	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SFY	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-133SFZ	1996	350 nm 0.35 μm 3.5e-4 mm	133 MHz 0.133 GHz 133,000 kHz	33 MHz 0.033 GHz 33,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-150ADW	1996	350 nm 0.35 μm 3.5e-4 mm	150 MHz 0.15 GHz 150,000 kHz	50 MHz 0.05 GHz 50,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-150ADY	1996	350 nm 0.35 μm 3.5e-4 mm	150 MHz 0.15 GHz 150,000 kHz	50 MHz 0.05 GHz 50,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-150ADZ	1996	350 nm 0.35 μm 3.5e-4 mm	150 MHz 0.15 GHz 150,000 kHz	50 MHz 0.05 GHz 50,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
AMD-X5-160		350 nm 0.35 μm 3.5e-4 mm	160 MHz 0.16 GHz 160,000 kHz	40 MHz 0.04 GHz 40,000 kHz	4,096 MiB 4,194,304 KiB 4,294,967,296 B 4 GiB 0.00391 TiB
Count: 17

Documents

Datasheets

• Am5x86 Microprocessor Family (March, 1996), Publication #19751
• AMD Enhanced Am486 (March, 1997), Publication #20736, includes DX5-133 models

Manuals

• AMD BIOS Development Guide (Enhanced Am486-Am5x86; August, 1995)

See Also

• Am486
• i486