Amiga Multitask

[Iggy]

All I'm saying is that preemptive multitasking isn't impressive from the computer hardware's point of view, because just about anything can do it properly

That last word invalidates your statement.
Properly would mean efficiently and with a measure of utility and many early microprocessor can not provide that.

The 6809, yes. The 68K, yes. Early Intel processors? Not well at all.
Minix was probably the only example of this that worked reasonably well (until the '386).

[commodorejohn]

There's nothing about the x86 architecture that prevents it from doing decent multitasking, even in the larval 16-bit phases. It's just that nobody did it well until way later, for stupid reasons.

[warpdesign]

I think what was impressive is that it was one of the first OS for "family computers" to have such an OS. Most other mainstream OS of the time (DOS/CP&M/TOS/MacOS) only had single task or simple cooperative multitasking. But Unix was already there, and way more sophisticated than AmigaOS, that wasn't what it was supposed to be anyway. Commodore wanted it out too fast. And that's maybe the most impressive: the timeframe used to release a fully GUI-OS...

But by the mid/end of the nineties it already showed its age: no RTG/RTA (yes: Windows 3.11 was more advanced in that regard), no memory protection, no virtual memory, not portable,... And despite mostly a rewrite (OS4/MOS/AROS), this hasn't changed. There is RTG/RTA, but that's it. Most big technical limitations are there...

We all agree it was impressive 27 years ago. But time has changed. Windows isn't based on DOS anymore. MacOS has now its roots in Unix/BSD. And AmigaOS is now the most limited.

[warpdesign]

AmigaOS 4 requires about 40-60mb to run. This is inexcusable: amigaos 1.x would run with 256kb (aie.: 0,25 mb)

[_ThEcRoW]

As far as multitasking... I don't think there is any comparison of amiga os and other available systems at the time.

I ran a bbs on pc... I wanted to do it on amiga os but couldn't afford an amiga 2000 at the time. I always had an amiga for me, and pc for the bbs, running
dos and desqview.

I ran a bbs and did alot of bbsing. On a 386 with desqview you could call a bbs and do something else at one time, but it crashed constantly and was not a joy to use. I could run my 1 node bbs and run perhaps some small apps in the background (the draw or a text editor) But the users noticed lags while I did this.

At the time time, I could use an amiga 500 with 2 meg ram and call a bbs and download files while playing a game, while playing mod files, while running dpaint in another screen, while waiting for the files to download, with almost never a crash...

Later, I got a 486. I tried running 4 phone lines (nodes on the bbs) on one machine, no way. I could do 2 lines max at 2400 baud on a 486 66dx2 with 32 megs ram.

Around the same time, a friend of mine ran 8 lines (6 - 2400 baud lines and 2 57600 lines) on an amiga 2000 with 25mhz 68030, with cnet. He could also
still play games, write letters, play mod files, play games, view gifs,and users rarely or never saw any lag.


Around that sime time.
Want to try windows for multitasking? Forget it, it was much slower and worse than desqview because the processor did everything, graphics, sound, all bogged down the main cpu.

Amiga worked better because the sound, graphics used custom
chips... and the os cooperated, spreading the workload across graphics
chips, sound chips and main cpu.

windows 95 things got a bit better, but not much. I still think an amiga 500
with 68000 and 2 meg of ram ran rings around a 200 mhz Pentium running windows 95 or 98 when it came to running multiple applications and a smooth user experience.

After windows 98, I gave up on dos/windows and moved to linux. Linux multitasks as smoothly as amiga. I sure miss the simplicity of knowing where
everything is in amiga though...

I should also mention, before amiga or pc I used a trs-80 color computer with os9, it multitasked beautifully on a 2mhz 6809 in 64k. Coming from that,
I couldn't believe the ****tiness of a "pc" with so much more resources not being able to do this effectively.  How can a computer that is like 25 times
faster than the 2mhz color computer not be able to run 2 applications smoothly multitasking? Bad design, and bad programming I think.

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?.

[psxphill]

There's nothing about the x86 architecture that prevents it from doing decent multitasking, even in the larval 16-bit phases. It's just that nobody did it well until way later, for stupid reasons.

If QDOS had been based on MPM instead of CPM then maybe we'd have had some form of multitasking.
 
However decent multitasking is a matter of opinion. While I loved the Amiga, the lack of memory protection was a huge downside. Especially if you're developing software, as it's more likely to crash. It wasn't until I started using Windows NT that I realise how useful memory protection was.

[Hattig]

My main multitasking was playing MOD files whilst editing graphics in DPaint and programming in Blitz Basic, with Workbench file management (or DOpus). That all ran quite happily on an A500, and it was smooth. It was a good workflow actually - not much to get in the way. Now it's too easy to procrastinate online!

[bitcpy]

Dont forget about Xenix. It ran very well on the 286 and 386 platform.
 

The 6809, yes. The 68K, yes. Early Intel processors? Not well at all.
Minix was probably the only example of this that worked reasonably well (until the '386).

[desiv]

Playing games alongside the bbs?. .... Or were you able to play shadow of the beast while running the bbs all in the same Amiga?.

Actually, there were lots of great games that multitasking.
I'm sure there's threads on them to search for..

Yeah, the games that took over the OS were out of the question, but there were still a good selection of games (yes commercial games) that were OS friendly.
Heck, going back to the early days, Mindwalker would multitask, tho I don't think it was an officially OS friendly app.
(You had to use the keys to pop back to WB IIRC, and I don't remember now if it had a quit back to WB.  Been too long..  But I know I would launch that one while using BBSs or whatever WAY back in the day...)

desiv

[commodorejohn]

But by the mid/end of the nineties it already showed its age: no RTG/RTA (yes: Windows 3.11 was more advanced in that regard), no memory protection, no virtual memory, not portable,... And despite mostly a rewrite (OS4/MOS/AROS), this hasn't changed. There is RTG/RTA, but that's it. Most big technical limitations are there...

What exactly does "RTG" stand for here? Certainly not "ReTargetable Graphics," it definitely supported that at least from WB3.1, with drivers...

We all agree it was impressive 27 years ago. But time has changed. Windows isn't based on DOS anymore.

You're right. Windows is no longer based on DOS, which was based on CP/M, which was based on RT-11. Windows is now based on VMS. So we have moved ahead one generation of DEC minicomputers and snapped back a couple levels of indirection to go from a Windows based on an OS from 1971 to a Windows based on an OS from 1975, while the rest of the modern computing ecosystem congratulates itself for being based on an OS from 1969. PROGRESS!

However decent multitasking is a matter of opinion. While I loved the Amiga, the lack of memory protection was a huge downside. Especially if you're developing software, as it's more likely to crash. It wasn't until I started using Windows NT that I realise how useful memory protection was.

I won't argue that memory protection is hugely useful, but it's not an absolute requirement. And anyway Iggy was talking about the 8086 in comparison to the 68000 and 6809, neither of which featured protected memory either.

[psxphill]

What exactly does "RTG" stand for here? Certainly not "ReTargetable Graphics," it definitely supported that at least from WB3.1, with drivers...

RTG wasn't really supported, it just had barely enough for Picasso/Cybergrafx. Real RTG was to be supported in the next OS.
 

I won't argue that memory protection is hugely useful, but it's not an absolute requirement. And anyway Iggy was talking about the 8086 in comparison to the 68000 and 6809, neither of which featured protected memory either.

And because of that, they could all multitask as badly as each other. Everything was fine as long as nobody did anything wrong. At that point co-operative multitasking vs pre-emptive multitasking becomes a difficult argument as well. Pre-emptive multitasking means you can still be run, even if some other software is so badly written that it never yields. But if it's that badly written then it's likely to be stomping all over memory. It's one of those things, like visual basic, that allows people to become developers who you really don't want to become developers.

[Thorham]

And because of that, they could all multitask as badly as each other.

Memory protection and multitasking are to separate things, because neither one requires the other. You could, for example, have a single tasking OS with memory protection.

Pre-emptive multitasking means you can still be run, even if some other software is so badly written that it never yields.

Why would you even want to use such badly written crap anyway?

[desiv]

At that point co-operative multitasking vs pre-emptive multitasking becomes a difficult argument as well.

In theory, yes.
But in practice, the Amiga applications in general behaved fairly well and the "end user" experience was pretty darn good.
Especially compared to the co-operative options at the time.

Both co-operative and non-memory protected pre-emptive multitasking required the apps to behave.
In general they did.
Yes, you had issues from time to time, but you could ID the bad apps pretty easily.

The fact is, all the early OSes crashed from time to time.
Multitasking or not.

Pre-emptive multitasking was a huge performance / functional benefit that, in reality, wasn't any less stable that the other options.
(With the exception of the Mac and multi-finder, which was pretty darn stable, but slow and painful, IMHO)

I used many of the options available at the time, and the Amiga wasn't any less stable, and was (IMHO) much more usable.

desiv

[Iggy]

Dont forget about Xenix. It ran very well on the 286 and 386 platform.

Yep. although it ran better on a 68K.
 
And only Minix ran on earlier processors.
 
BTW I had an MPM machine (got rid of it).
I thought those were Z-80 powered.

[commodorejohn]

BTW I had an MPM machine (got rid of it).
I thought those were Z-80 powered.

They were. (Though I don't know if, like CP/M, there was a 68k variant.) MP/M was brought up in the context of "what if QDOS had been based on that instead."

[itix]

Pre-emptive multitasking means you can still be run, even if some other software is so badly written that it never yields.

Why would you even want to use such badly written crap anyway?

It sort of degrades pre-emptive multitasking to co-operative if before executing application you have to figure out is application really multitasking or not. Many Amiga applications from golden era dont multitask at all.