Why 8086 can grow in to x86, But 6502 can"t?

[TROLOZY]

now x86 is most used cpu type in home PC, Workstation, Server, and etc,

if 6502 and CPU based on it, was more popular choice in 80's . Why can't 6502 grow?

[BitWise]

It did. It inspired the design of the ARM RISC processor.

[TROLOZY]

BitWise wrote:

It did. It inspired the design of the ARM RISC processor.

i think ARM and other RISC CPUs aren't really a part of the "65x-ish family" ,

[drogon]

TROLOZY wrote:

BitWise wrote:

It did. It inspired the design of the ARM RISC processor.

i think ARM and other RISC CPUs aren't really a part of the "65x-ish family" ,

they're not directly part of it, but the ARM was designed by the people who had already a good history of designing 6502 based systems and the simplicity of the (early) ARM designs really does reflect the relative simplicity of the 6502. The ARM was simulated and tested on of of their 6502 based BBC Micros in the mid 80's by the boffins at Acorn.

However another answer is simply the usual too-little, too-late. The 816 is the 16-bit 6502, but when it came to market, there was a much bigger player in the "PC" field - IBM. the 65816 was used in the Apple //gs and Super NES systems.

-Gordon

[GARTHWILSON]

I have links to various 16- and 32-bit 65-family processors here, a few of which made it to production and the rest of which did not, for various reasons. Bill Mensch said a few years ago that if the 65c02 were implemented in the newest (for that time) silicon processes, it should be able to do 10GHz. Obviously memory and I/O would have to be all on the same IC, since you're not going to be able to run an external bus at that speed. The 65816 would probably be slightly slower in clock speed. The '02 and '816 are still being produced. The '02 however was intended for embedded control, not home computers. Apparently the reason it made it into home computers was its low price.

[1024MAK]

To understand the development of the various microprocessors, you have to put them into context both from the original design and intended market and from the actual mass production date. Also the competition from rival manufacturers.

This is the timeline that I have been working on:
1971 - Intel 4004 4 bit
1972 - Intel 8008 (originally the 1201) 8 bit
1974 - Intel 4040 4 bit (enhanced 4004)
1974 - Intel 8080 8 bit
1974 - Motorola 6800 8 bit
1975 - MOS 6501 8 bit
1975 - MOS 6502 8 bit (see notes below)
1976 - Zilog Z80 8 bit
1976 - Intel 8085 8 bit (followed by the 8085A, a bug fixed version)
1978 - Intel 8086 16 bit
1978 - Motorola 6809 8 bit
1979 - Intel 8088 16 bit but with a 8 bit data bus
1979 - Zilog Z8000 (Z8001, Z8002) 16 bit
1979 - Motorola 68000 16/32 bit but with a 16 bit data bus
1980 - Intel 8085AH (HMOS version of the 8085A)
1982 - Intel 80186 16 bit
1982 - Intel 80188 16 bit but with a 8 bit data bus
1982 - Intel 80286 16 bit
1982 - Motorola 68008 16/32 bit but with a 8 bit data bus
1982 - Motorola 68010 16/32 bit but with a 16 bit data bus
1982 - Hitachi 6309 8 bit CMOS, an enhanced version of the 6809
1982 - National Semiconductor 32016 32 bit but with a 16 bit data bus
1984 - Motorola 68012 16/32 bit but with a 16 bit data bus
1984 - Motorola 68020 32 bit
1984 - National Semiconductor 32032 32 bit
1985 - Intel 80386 32 bit
1985 - Hitachi HD64180 (enhanced Z80)
1985 - National Semiconductor 32332 32 bit
1986 - Zilog Z80000 32 bit
1987 - National Semiconductor 32532 32 bit
1987 - ARM2 32 bit
1987 - Motorola 68030 32 bit
1987 - Zilog Z280
1991 - Motorola 68040 32 bit
1994 - Motorola 68060 32 bit
1994 - Zilog Z380
2001 - Zilog eZ80 (enhanced Z80)

Note that the dates are wherever possible, dates when the first units were available, or announced as being available.

Others, but dates not yet known:
80C85A CMOS version of the 8085A
Zilog Z180 (enhanced Z80)(Z80180, Z8S180, Z8L180)
Zilog Z64180 (enhanced Z80)
Zilog Z320 ( CMOS version of the Z80000)

65xx, 65Cxx and 65SCxx processors
These versions were available:
6501
6502
6503
6504
6505
6506
6507
6512
6513
6514
6515
65C02
65C102
65C112
65SC02
65SC03
65SC04
65SC05
65SC06
65SC07
65SC12
65SC13
65SC14
65SC15
65SC102
65SC103
65SC104
65SC105
65SC106
65SC107
65SC112
65SC115

See also https://en.wikipedia.org/wiki/Microprocessor_chronology

The 6501 and 6502 objective was to be simple and inexpensive, with the expectation that the main market would be embedded applications.

It takes time to design and produce complex intergraded circuits. And MOS had to battle Motorola both in the market and in court. MOS were then bought by Commodore.

In the meantime, as you can see many other microprocessors were being developed and produced. The Zilog Z80A became the biggest competition to the 6502 not the Motorola 6800.

It was not only the producers of the 6502 that failed to make much of dent in the 16 bit and 32 bit markets. Zilog were also not very successful. Neither were National Semiconductor.

Apple with their Macintosh range used Motorola 68K (68000) processors.

In Europe, for home computers, Motorola with their 68000 were successful and around the world for business use, it was Intel with the 8086, and 8088. Then later the 80286 etc.

Once Microsoft MS-DOS running on IBM PCs (or compatibles) became a “standard”, any other architecture would be very, very difficult to become successful in the general computing market.

As well as all the 8 bit microprocessors, 16/32 bit microprocessors with 8 bit data busses and reduced address busses also provided competition in both home computers and in embedded applications.

Embedded applications were also the prime market for microcontrollers (and there is a vast range of these).

In such heavily competitive markets, it’s hard to successfully design, launch and market new microprocessors.

ARM were successful more through accident than design, as the ARM microprocessors could operate efficiently at low power. Exactly what you want from battery powered equipment that has to be pocket sized.

Mark

[fhw72]

You forgot the 6508, 6509, 6510, 8501, 8502.

[Druzyek]

I think having 16 bit registers 6 years or so before the 65C816 came out, along with a 16 bit wide data bus (which the 65C816 doesn't have) probably had a lot to do with it.

[BigEd]

If you could add in the '816, Mark, we might see how late it was! I think what happened was that famously-frugal Commodore didn't have motivation to make a new CPU - having bought MOS, they didn't pursue big CPU improvements. It took Mensch and Apple to re-start the 6502 evolution, rather late and rather compromised by needing to be very very compatible.

[cbmeeks]

1024MAK wrote:

To understand the development of the various microprocessors, you have to put them into context both from the original design and intended market and from the actual mass production date. Also the competition from rival manufacturers......

What about the TMS line of CPU's?

[Chromatix]

It should be remembered that the 8086 was a 16-bit CPU from the start, with the attendant complications in selecting register and operand sizes baked in (at least partly through prefix codes). It could later be extended to 32 bits (with the 80386) and then SIMD (Pentium MMX, K6-III, Pentium 3), because the ISA had fairly obvious places to permit extensions of that sort (probably itself a legacy of the earlier progression from 8008 to 8080 to 8086). To support 64 bits, AMD did a bit of house cleaning and made it a distinct mode, rather than just an ISA extension, clearing away a bunch of legacy cruft and thus freeing up more opcodes to use as prefixes.

The 6502 was not specifically designed with this sort of extensibility in mind - it was only designed to be as cheap as possible while still being practically usable. All of the opcodes were singular, with at most one trailing operand, and no prefix codes. This made it possibly the most RISC-like CISC CPU in existence. The later extension to 16 bits ALU in the 65816 was done by adding mode selectors, not prefix codes, with only the 24-bit addressing modes (and a few other niceties) implemented by using spare opcodes. This left only two opcodes technically available for further expansion; WDM (explicitly intended as a prefix code) and COP (intended for triggering logically-external coprocessors, a la F-line and A-line opcodes on the 68K).

It could be argued that the 65816, for all its weird quirks, is *still* a cleaner and more efficient design than the 8086.

As pointed out, the ARM CPU is the spiritual successor to the 6502, and has been exceptionally successful. I heard it quoted some years ago that there are more ARM CPUs in existence than any other; there are in fact probably more ARM cores in your PC than x86-family cores. Second place goes to PowerPC.

[1024MAK]

fhw72 wrote:

You forgot the 6508, 6509, 6510, 8501, 8502.

Not forgotten... There is also the Atari version of the 6502...

BigEd wrote:

If you could add in the '816, Mark, we might see how late it was! I think what happened was that famously-frugal Commodore didn't have motivation to make a new CPU - having bought MOS, they didn't pursue big CPU improvements. It took Mensch and Apple to re-start the 6502 evolution, rather late and rather compromised by needing to be very very compatible.

I will indeed add the ‘816...

cbmeeks wrote:

What about the TMS line of CPU's?

These are also planned to be added...

However, real life has a nasty habit of getting in the way!

Mark

[TROLOZY]

Chromatix wrote:

I heard it quoted some years ago that there are more ARM CPUs in existence than any other; there are in fact probably more ARM cores in your PC than x86-family cores. Second place goes to PowerPC.

It’s like saying you have more electro motor than engine piston cylinder in your car,
By counting the side window roller and air conditioner fan and stuff

[Chromatix]

Well, it would be silly and wasteful to install a petrol engine for each of those tasks, wouldn't it?

[TROLOZY]

Chromatix wrote:

Well, it would be silly and wasteful to install a petrol engine for each of those tasks, wouldn't it?

They don’t run the car, like those ARM won’t process your mouse click and open your exe installed,
You might say the RISC based system exists, like most smartphone , some tablet , and television and things, But it’s like “electro moped” , not a car.