Amiga Multitask

[KimmoK]

>I think the preemptive multitasking feature of AmigaOS is mostly overrated.

It can not be.
But a lot of people had too limited setup to truly use it.

>Without memory protection, preemptive multitasking doesn't result in a significantly better end user experience.

Yes it did. After you found stable programs, you could multitask a workd day without any symptoms of problems.

I got A2000C(1MchipRAM)+2MB+20MBHDD+Bridgeboard+Multisync in 1989, it was a superb workstation untill 1994 (I sold it at that time). I used multitasking continuously. I even tried to favour games with HDD installation + multitasking option. Did some renderings in multitasking, dock writing & picture editing for the doc...
And I had mods playing on the background, without any hickups. One nice thing was be able to use music apps and animation tools at the same time and record the animation with sound to VHS.

>Love the Amiga to death but back in the day when I first got my hands on a 386DX/25 w/ 8MiB of RAM and 1MiB trident VGA board,

My first own real x86 was P1/75Mhz with some 8MB  RAM etc (in 1995).
It could in no way compare with my A4k.
(x86 had more raw power but it was slower than 040/25 systemn anyway, everywhere. And unstable. Cheaper, though.)

(before late 1995 I used bridgeboard with my A2000 and PC Task on my 4k for occasional x86 need, for graduation work I had P1/60+Win3.11 at work, but I bought my own HW to get rid some of the troubles.)


>I didn't miss the Amiga one bit. I'd go so far as to say that Windows 3.1 was more sophisticated than classic AmigaOS ever was. It certainly was more stable.

My experience is totally different.
On Amiga you can set up the system to be stable. You cound stretch the system unbelieveably.
But pre-NT windows systems always broke if you truly used them a lot (for more than word2).

(and you had to do insane amount of tricks to get every SW + games to work. For example I had 32bit soundcard on the P1/75, but never got it working with DOS games (90% of x86 game content was in DOS). And usually you had to kill win95 to run DOS games ... and even then you had to have the know how to set high/low/whatever mem and IRQs right .... AAAAARGHHHHH!!!!!).


For me. The biggest advancement on my devices after AOS1.2 in multitasking was the Executive task scheduler.
Suddenly I could automate the priority settings. 600%cpu load without loosing any responsiveness...
And also Amigas virtual memory was superb. I was able to set what apps use virtual memory, the rest of the system remained 99% responsive even when there was a lot of swapping ongoing. .... oh those times ....
Yes, most of my HW have MP etc etc. But still the multitasking is behind Amiga basics. (to my liking)

[KimmoK]

One nice multitasking thing on AOS has been that you can continue your doings without any multitasking quirks even when handling the main media, floppy disks. You could do disk to disk copies and backups while continuing yoruy work and music listening.

Later it was the same with CD-R. You could write CD and multitask without as big risk of failing burn as on Win95 (when using modest HW). I think minimum recommended CPU for CDR burning was some 200Mhz CPU on x86??? On A2000 some people did it with 030/25Mhz or less, in multitasking. (when burnproof HW became available, things got forgotten)

And for multitasking....
For some reason, even when DMA was not used, Amigas could do faster HDD data transfers and with lower CPU overhead than on x86. It affected in multitasking greatly in late 90's.

[KimmoK]

he likes to have the best and it was the most expensive computer at the place he went. I asked him what he's going to do with it? He said "Check my emails, facebook, and surf the internet..

Damn! If x1000 would have been available on that shop...  ;-)

[KimmoK]

@itix "For proper multitasking you needed more memory and fast hard disks..."

On my A2k that had 1M chip and 2M FAST +200kB/sec hard drive the experience was already insanely nice.

A friend of mine got A590 + RAM for his A500 and also it was superb (up to 2.5MB sec disk transfers and DMA IIRC, better I/O speed than later on my A4k).

btw. Did ImageFX internal virtual memory require MMU? I think not.
VMEM and and Gigamem required MMU.

[KimmoK]

Some software needs alot of ram because ....

And that again brought something to my mind.
After we got enough RAM (16MB on classic, 512MB on bigger boxes) and especially nowdays I think SW code should never be swapped to disk. Multitasking is more smooth when only heavy data is swapped (the way how one could do it on 68k with ImageFX etc).

It's a shame that for many apps in the mainstream developers spend absolutely no time in optimizing and the end user pays the bill.
(a few days ago I spent two hours waiting for NI DAQ SW to install on a high spec workstation and that kind of driver monsters make any computer to crawl (when silly OS is used). I imagine it would take a few days to re-install everything, so we keep HDD images in safe place in case of HDD hazards.)

[KimmoK]

@commodorejohn
"turn off paging entirely, come think... "

Good luck with that. Last time I had windows installed, there was no way to disable paging file. Even if you disable it from the system tool, paging file appears after anyway and swapping happens.
(+M$ applications do their own swapping, at least word does it with large documents, no matter if you have terabyte of RAM.)


@koaftder
" I never understood why so many folks clung to 2k"
Because not all apps run on XP?
Or because XP does not run on their HW?
Those things happen.

[KimmoK]

Since the OS didn't allow to share lots of resources (sound access was exclusive for example), it also limits what can be done using multitasking. No way to run two apps accessing paula for example...

On my a4k I have been using AHI about as long as I remember, to get 14bit calibrated audio (up to 56khz or something). With that setup you can run as many AHI aware audio applications at the same time without problems.

But sure, very old apps that bang the HW directly can crash or lock up.

Also, on Amiga it has been pretty simple to use 4...7 audio cards at the same time without problems. Doubt any 486 did that... ;-)

[KimmoK]

It wasn't more usable because of the pre-emptive multitasking though. Especially when running code that did Forbid() or Disable(), which because of the OS design pretty much every program had to.

I think I have never seen any symptoms of that. AOS multitasking has always been smoother than on any other OS I've used.

(I'm sure HW drivers used that, but also file handling was smoothest on Amiga, and web browsing over ethernet.)

For example, IIRC, when I ran 16bit SW in while(1) loop on win95 it pretty much locked up (IIRC, not absolutely sure because at work we used 3.11 and I might mix up something), and it was supposed be pre-emptively multitasking... hmmm.... I should have the demo SW somewhere.... should try again in qemu.

[KimmoK]

Playing games alongside the bbs?. What kind of games? S****y games like minesweeper doesn't count as a game. Or were you able to play shadow of the beast while running the bbs all in the same Amiga?.

RailRoadTycoon, Civilization, Colonization, OilImperium(IIRC), Foundation, MAME and other  games under emulation, etc...
Hundred(s) of games I believe. Pretty much every HDD installable game.