What's so bad about Intel 8086 in technical terms?

[Hans_]

Such techniques are still used in some operating system you know very well ;-)

I was expecting someone to make a snarky comment like this...

Yes, Extended Memory Objects bear a strong resemblance to segmented memory/memory banks, and it is a compromise.

However, unlike memory banks, mapping in an ExtMem object does not redirect the entire address space to the newly mapped memory. So accesses to all 2GiB of "normal" RAM go unimpeded; no bank switching necessary. That does make it less problematic, although developers should still heed Hans-Joerg's advice to treat it more like a file that's accessed by offset rather than as RAM.

Alas, on C64 you had to use memory banks to access all 64K RAM but for some reason 6502 and its descendants are not considered as "bad designs" like 8088/8086. Certainly 8088 was not too nice to program for but when I did some coding on 486 in Turbo Pascal it was not bad at all.

Possibly because the "C64 was cool." Or maybe because the 6502 & decendants didn't go on to become the core of mainstream computers.

Yes, a compiler can take care of the bank switching for you. Plus, the 80486 also had a mode allowing full 32-bit RAM access without switching.

Hans

[commodorejohn]

Yes, a compiler can take care of the bank switching for you. Plus, the 80486 also had a mode allowing full 32-bit RAM access without switching.

As did the 386 - unfortunately, it took a good long while for the OS to catch up.

[itix]

Possibly because the "C64 was cool." Or maybe because the 6502 & decendants didn't go on to become the core of mainstream computers.

There was 16-bit variant which had two operation modes, emulation mode and native mode (like 80286 had real mode and protected mode) and yet another variant was used by Nintendo in SNES.

Yes I see you only mentioned mainstream computers ;-)

Yes, a compiler can take care of the bank switching for you. Plus, the 80486 also had a mode allowing full 32-bit RAM access without switching.

80386 had that already. 386 was actually quite decent chip unlike its predecessor, 80286.

But to me, as a developer, it does not matter if there is bank switching involved or if CPU is using slower base+index segment memory model. Only user experience is important.

[Hans_]

80386 had that already. 386 was actually quite decent chip unlike its predecessor, 80286.

Yes, the 386 already had it. Intel had a hard time getting people to use it, but the capability was there.

But to me, as a developer, it does not matter if there is bank switching involved or if CPU is using slower base+index segment memory model. Only user experience is important.

AFAIK, it did hurt the user experience early on due to the inevitable higher occurrence of bugs that it caused. It's easy to be dismissive when you're used to using compilers that hide these kinds of complexities and don't need to write hand-optimised assembly, but programmers weren't always so well equipped.

Hans

[commodorejohn]

Yes, the 386 already had it. Intel had a hard time getting people to use it, but the capability was there.

Well, they had a hard time getting DOS and Windows to use it, on account of the PC BIOS, MS-DOS, and pre-NT/95 Windows being designed for real mode. Xenix supported protected mode all the way back in 1987.

[bbond007]

I had a 286 20mmhz. The 386sx or 386dx where what most people were getting but I was tying to save a little money. Even with the crappy instruction set it was very fast for a lot less money than about anything else. I really just ran DOS games and Turbo Pascal, BBS programs.

[persia]

Really at this point in time there is no competition on the desktop/laptop.  i5 and i7 far outclass anything offered by ARM, and there are no other practical competitors left.

[commodorejohn]

ARM's getting to the point of being quite adequate for users who don't require a high-performance gaming machine, though - and it does it at a lower price and a lot less power consumption. Its biggest handicap is that the only software support it has outside of iOS and Android is experimental nerd OSes like the free Unices, AROS, or RISC OS. Interesting stuff to be sure, but nothing that could make it a serious competitor in the general market.

[persia]

I don't see an end to the divided market with ARM on the tablet and phone and intel on the desktop/laptop.

[freqmax]

The iAPX 432 was their proper cpu, which was a failure (like all proper projects tend to do).

Why did it fail?

Ugly is an emotive description of technical design compromises. I'm not going to play at being some kind of impassive robot thing.

One could also call it a judgment based on experience of good engineering.

As did the 386 - unfortunately, it took a good long while for the OS to catch up.

BSD operating systems (or most unix:es) provided an abstraction on x86 to do away with the dysfunctional segmentation memory handling. Mainly by activating the protected mode memory model and provide a compiler environment that did away with it.

Really at this point in time there is no competition on the desktop/laptop. i5 and i7 far outclass anything offered by ARM, and there are no other practical competitors left.

Actually when you need a machine that perform as fast as possible per watt used then ARM beats Intel. This also goes for solder ability of the chip package and stable chip offerings. Intel has a habit of EOL:ing chips while you design a circuit board for them..

Also a single chip ARM is now approaching the capacity of an A500 with RAM of 192 kB vs 512 kB and flash/ROM of 1024 kB vs 256 kB. So you could fit the Amiga ROM + workbench into ONE ARM chip and use the powerful DMA circuits to do graphics and sound. And all that at 168 MHz for like 10 EUR. Neat!
(for serious stuff one needs more DRAM, but those 192 kB goes a long way..)

What Intel has going is an existing software base and knowledge from developers. Their processors are also most likely the fastest for single thread applications. In many cases the x86 platform is the cheapest performance per instruction per second too. But the platform is a hodgepod of bad compromises. They lately also left the open nature of the platform (UEFI, TPM, CPUID etc).

[biggun]

Actually when you need a machine that perform as fast as possible per watt used then ARM beats Intel.
...

The performance depends very much in the task / benchmark you run.
In my experience current Intel cores are generally very good in many different tasks.

Here is a benchmark which stresses cache and conditional code execution.
The 68060 is not bad for its age.
Its faster than than a 240 Mhz Coldfire.

While modern Intel chips score very good.
The tested ARM chips were not impressive.

http://www.apollo-core.com/sortbench/index.htm?page=benchmarks

[freqmax]

I think the keyword here is Real-world-scenarios. Also the ARM can go really low in power consumption absolute terms.

(Dunno how MIPS fares in this)

[Faerytale]

x86 design was good enough for World domination.

[bloodline]

x86 design was good enough for World domination.

Nothing stands in the way of progress more than "good enough".

[commodorejohn]

Nothing stands in the way of progress more than "good enough".

But, but, but bloodline! Don't you know that Worse is Better? People on the Internet said it, so it must be true!

[freqmax]

Off-topic: IBM was early with computing for commercial companies and thus had a foothold with business people (MBA beancounters). IBM wanted to a bite of the personal computer market so they throw together a team that put together some crappy chips from some crappy chip designer like Intel. They then tried to get CP/M but were too important to wait for a good deal so got a crap software to go with this design.

The next phase is that because they consider it an unimportant product they release drawings and documentation. Businesses buy it because (1) IBM reputation (2) cheap compared to mainframe. And then it takes of.

So what's needed for world domination is contacts and reputation..
x86 was bought by clueless MBA:s because it had "IBM" stamped onto it. Now the actual people doing the buying may be different people but the management culture still permeates. And once there was software for crap hw/sw the other software had to be compatible with the former which was used in the all important "business environment" ..

Take out the reputation and contacts from IBM in the 1980s and the problem would likely been a lot less severe. Add compability layer to other platforms to snuff out the compability aspect and there might be a solution. The current solution seems to be that x86 is to inefficient and Windows is just a too big blob of code for mobile environments where power and resources utilization really counts. Besides Microsoft was just too busy entrenching themself in a market that was soon to be competing with a whole new market they perhaps didn't "get".