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The Life Cycle of a CPU

In today's time a CPU may only stay on the market for 24 months, some even less before it is replaced by something new and greater. More features, more cache, today's market begs, even cries for more, and CPU manufacturers are quick to jump in with something new, but not always great. This was not always so.

There was a time not so long ago when people begged for more, and CPU manufacturers strained to produce but were not always successful. Often new designs WERE created that WERE better, but the price was absolutely insane. This led to the older CPUs continued production and use. Sometimes for many, many years past its release date. Speeds would increase (or not), power consumption and die size would be reduced, often the supply or I/O voltages would be designed to work at lower levels but still be 'tolerant' to the original specifications.

It is important to see this life cycle of CPUs as they matured in the market to realize the importance of some of these historic chips. Chips designed in the 1970s are STILL being made. Where as some chips designed in the 1990s lasted for but a few months. I will start with the 1970s with such famous chips as the Intel 4004 and the MOS 6502 and slowly we will look forward to the 1990's.

CPU Type
Introduced
Last Production
Lifetime Notes:
Intel 4004
1971
1981
10
 
Intel 8008
1972
1983
11
 
Intel 8080
1974
1990
16
 
Intel 4040
1974
1981
7
 
Motorola 6800
1974
2006
32
 
TI TMS1000
1974
1985
11
 
Microchip PIC16
1975
2009
34  
MOS 6502
1975
2009
34
SS
AMD 2901
1975
2009
34
SS
Zilog Z80
1976
2009
33
 
Intel 8085
1976
2000
24
SS
Fairchild 3850
1976
1984
8
 
Signetics 2650
1976
1987
11
 
Intel MCS-48
1976
2009
33
SS
RCA 1802
1977
1995
18
SS
Intel 8086
1978
1998
20
SS
Intel 8088
1979
1998
19
SS
Motorola 68000
1979
2009
30
 
Intel MCS-51
1980
2009
29
SS
Intel 80186/8
1982
2009
27
SS
Intel 80286
1982
1991
9
SS
NEC V20
1984
1995
11
 
Intel 80386
1985
2007
22
EMB
AMD 29000
1987
1996
9
 
Intel i960
1988
2007
19
 
Intel i486
1989
2007
16
EMB
AMD 29050
1990
2005
15
SS
AMD 29030
1991
1998
7
 
Digital 21064
1991
1997
6
 
Intel Pentium
1993
2009
16
 
Intel Pentium II
1995
2001
6
 
Cyrix 6x86
1995
2000
5
 
AMD K5
1996
1998
2
 
Sun UltraSparc II
1996
2001
5
 
AMD K6
1997
1998
1
 
IDT Winchip
1997
2000
3
 
AMD K6-2
1998
2001
3
 
Intel Pentium III
1999
2009
10
 
Notes:
SS - Last produced by a Second Source
EMB: Embedded Version (made by third party) was the last produced


It is very apparent what is happening here. CPUs introduced in the late 1970's and early 1980's are often still in use today. Why is this so? Certainly today's designs are much more robust however, when you design a printer or a sewing machine you do not want a P4 or a AMD K6 to power it. You want something simple, cheap and easy to use. Something like a Zilog Z80, MOS 6502 or NEC 7810 is ALL many applications need. They have the added benefit of having HUGE code bases (amount of software ALREADY written for them). In other words, if it aint broke, don't fix it.

If you look closely at the types of CPUs made late in the life cycle you will see a shift in production from commercial spec chips to chips that are T, I and M spec. Extended Temperature, Industrial, and Military. All areas where one wants something to work the same way always. These markets are some of the biggest for 'old' CPUs. It works fine for them, and is not near as sensitive as modern CPUs to variations in voltage and temperature. A lot of these industrial chips will allow a 15% fluctuation in voltage, at temperatures from -50C to 125C. Try THAT with a P4.

Today's modern CPUs are VERY specialized. Yes you can run about 100,000 applications on an AMD K6 on your PC, but where else do you see AMD K6 CPUs? That's right, they ONLY exist in computers (or computerized routers). Most all computing needs are NOT sitting on your desk so you can surf eBay and play Doom III, they are in your car, your cell phone, your printers and even your microwave. Control applications account for 90% of the CPU market.

In the last few years Intel has been working hard to gain back alot of the embedded customers they once had. With their new CPUs (Atom etc) they will have several specs that they guarentee an End-Of-Life no earlier then 7 years from when it first comes out. This gives engineers a bit more breathing room in their design life analysis.

. If I placed the ARM core or any of the MIPS cores in this list you would see them still in production. Why? because they are simple (RISC based in most cases) CPUs that lend themselves to MANY different applications. They are useless for the PC (Ask Acorn computers about ARM devices in the PC ;)) but for anything else in the world they work great.

Something else of interesting note: Speed
Or the lack of, many of the 'old' CPUs still in production are being made at exactly the same speed as they were when they were introduced, or not much faster. The 6502 made now by WDC is clocked at the SAME speed as 30 years ago. The Zilog Z80 has been clocked up to 20MHz but is still available at 6Mhz. The Intel i186 is the exact same thing, still available at its initial speed.

The MCS-51 is a different story. It is a very robust architecture and lends itself to high clock speeds. It was released at 12MHz in 1980 and stayed at 12MHz for 15 years or more. There are now several companies making hi-speed 8051 solutions (Dallas-Maxim @ 50 MHz, Si-Labs (formerly Cygnal) @ 100MHz, Atmel @ 33MHz). This is because the 8051 is so easy to program and work with and actually benefits from higher clocks.


 
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