Amiga Multitask

[itix]

Well, about stability you mix OS and applications, no memory protection forced serious Amiga programmers to write more robust programs, if you run a bad one the OS won't help you there. Kamelito

Neither did Windows 3.x. There Windows applications were running inside a single process and applications could share memory like Amiga does. What made it finally quite unstable piece of crap was trying to retrofit paging and virtual memory to this mess. Applications had to lock handles to convert them to real memory pointers but sometimes programmers were not careful. Sometimes they were using stale pointer that worked until memory paging kicked in.

[itix]

I'm trying to imagine a virtual-memory system on 8MHz and 28 KB/s floppy disks, but I can't think over the screaming in my brain. I think there may be a lesson in there somewhere.

Indeed. For proper multitasking you needed more memory and fast hard disks...

I remember when I was coding some application on my Amiga 500. It had 1MB RAM only and when asm source code was over 150 kB it was no longer possible compile it while keeping my editor running on a background. So I had to save my code to a floppy and close editor to run compiler. Only to find out I had made small typo and had to edit code again. Back then I didnt have an access to memory conservative compilers and had to use A68k and Blink. Those were times...

[commodorejohn]

Indeed. For proper multitasking you needed more memory and fast hard disks...

Alternatively, you could just have efficient software that maximizes free memory for your actual work purposes and enough RAM to fit the task at hand, rather than churning data to and fro over a disk interface many orders of magnitude slower than the RAM which is itself likely not actually fast enough to keep up with the demands of the processor.

But, you know, that'd just be crazy.

[itix]

Alternatively, you could just have efficient software that maximizes free memory for your actual work purposes and enough RAM to fit the task at hand, rather than churning data to and fro over a disk interface many orders of magnitude slower than the RAM which is itself likely not actually fast enough to keep up with the demands of the processor.

But, you know, that'd just be crazy.

C64 coders were totally crazy. They had only 64 kB and had to use all imaginable tricks to save few hundred bytes. But still, no matter how efficiently it is done, there is always upper limit...

But actually on Amiga the limit was in chip ram. Deluxe Paint was designed to use chip ram sparingly but code size was not important when it wasnt going to chip ram. It wasnt always important to optimize code for size and not even your data.

Obviously chip ram limitation crippled Amiga multitasking at some point. Even when there was enough (fast) ram there wasnt enough chip ram to store gfx and sound. Nothing is perfect, not even on Amiga :-)

[commodorejohn]

True enough - no existing system is an ideal system. Still, I'd place more stock in good coding than hacky disk-swapping any day.

[djos]

I did like OS/2, but they were behind the curve
OS/2 Warp was awesome tho...  A great OS..  ;-)
And released a year before Win95.  Too bad they couldn't have marketed it better.

Agreed, OS/2 Warp was amazing and win95 sucked balls but by that time microsoft had a death grip on the OEM's and they wouldn't ship pc's without an MS OS.

There are also people that say that the Windows 3.1 application compatibility helped kill it.  Developers saw no reason to write a native OS/2 version of their app if it would run (mostly) already.

Yeah that prolly didnt help either.

[vidarh]

I know.
 
The thread was about: what was reality, not what was possible.

And the reality was that there were environments for the C64 that allowed you to multi-task. Shipping. As commercial products (I owned a copy of the aforementioned Laser BASIC for example). Just not built into ROM. Of course there were multi-tasking on lots of larger systems long before the Amiga as well.

The point is not to diminish the accomplishment of the Amiga, just that what was impressive about the Amiga was not multi-tasking per se, but an OS that actually combined multiple features in a way that made multi-tasking not just practical, but useful.

E.g. without windowing and abstracted device access and enough memory and CPU, multi-tasking on more primitive machines or OS's was a novelty, and the machines and OS's that could do preemptive multi-tasking as well or better than the Amiga at the time were not targeting consumers.

[vidarh]

Indeed. For proper multitasking you needed more memory and fast hard disks...

I remember when I was coding some application on my Amiga 500. It had 1MB RAM only and when asm source code was over 150 kB it was no longer possible compile it while keeping my editor running on a background.

FrexxEd (which I'm in theory working - at significantly slower than snails pace - on upgrading; I've actually committed stuff to the repository this year, honest) actually has an ingenious way to conserve RAM there - something you'd only see on a machine like the Amiga, largely because it itsn't worth the hassle any more in the day of multi-GB RAM machines:

Export the buffers as a filesystem handler.

You can mount FrexxEd: and dir it to list the files that are currently open in the editor, and run whatever applications you want on them without wasting memory on additional buffers.

It's elegant in a way, but people without experience with a machine like the Amiga takes one look at it and goes "wha?!?!? Why don't you just save it to a temporary file". Then I have to explain how that might have meant having to switch floppies and stuff

[haywirepc]

os9 could do very effective multitasking in 64k on a color computer 2. This is a very primitive example but still....

http://www.youtube.com/watch?v=GhQGknYPl1Y

When color computer 3 came with 512k, this 8 bit with os9 kicked the ass of any pc. I could be on any ansi bbs while playing a 128 color game on a seperate full screen page, download files on my 20 meg mfm hard drive, while text editing or writing basic programs. In short, the computer didn't make you wait.

At one time, I had two phone lines connected to my coco and could call 2 bbs systems at 2400 baud in seperate os9 "windows".

It was primitive but beautiful. Get used to being able to do that and you can't stand a single tasking system, which is why I went to amiga next.

It was the only system that would let me work like I was used to.  I considered amiga os to be a vast improvement to what I was used to. I would render graphics while calling bbs systems or downloading files. I always had a few screens going, and it was beautiful.

Today, people with 10 tons of resources are spoiled. One of my neighbors just bought a 6 core machine, simply because he has 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. There is 5/6th of computing power wasted on that guy.

[danbeaver]

Remember, UNIX was originally developed on a DEC PDP-7 to multiuser+multitask in 1969; The PDP series (oddly they were 18-bit'ers) had had a very similar instruction set with the MOS 6502

As a side note: Compute! Magazine published a simple multitasking piece of code that used the NMI (Non-Maskable Interrupt) vector to do it on a C64; one of my early efforts changed the Basic start/end vectors to but Basic in that top 4K meant for ml programs leaving the 32K below it as free ram. It was for a BBS Terminal program that put downloads in the large buffer away from the code..

Did anybody remember the Mac OS's early version of a task switcher that went from task to task by clicking a button?

Sorry about this post, my ADD is showing

[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.

[commodorejohn]

Remember, UNIX was originally developed on a DEC PDP-7 to multiuser+multitask in 1969; The PDP series (oddly they were 18-bit'ers) had had a very similar instruction set with the MOS 6502

Actually they were all over the place, with (off the top of my head) 12, 16, and 18-bit offerings of quite varied designs. (18-bit actually wasn't odd at the time, quite the opposite in fact; I'm not sure exactly where it comes from, but I expect that for scientific purposes having an integer range that encompassed all the way from +99,999 to -99,999 with room to spare made it easy to think of "five-digit integer capability" or somesuch.)

The PDP-11 was actually a big influence on the design of the 68000; you can thank it for the Amiga having a decent complement of truly general-purpose registers instead of the 8086's frol-de-rol with A, B, C, and D all being able to do different overlapping but never identical sets of things...

[Digiman]

Prior to the Amiga (later renamed Amiga 1000 to distinguish with those ugly 500/2000 replacements coming) the only multi-tasking OS on a home/personal computer was with the Sinclair QL. This however is not a GUI based multi-tasking OS.

So yes it was the first, and if you ever used a 1mb Atari ST over a 1mb Amiga 1000 you will instantly appreciate the option of multi-tasking.

Secondly not only was it the more sophisticated pre-emptive type (using a round robin timeslice scheduler?) but it was also quite capable of load balancing and prioritising well and it was mighty efficient due to the Kernal.

So in summary, before Windows XP in 2002 or OS/2 2.0 onwards maybe half a decade before that....multitasking on everything else was a load of pizz poor marketing bullcrap.

For nearly a decade and a half it seriously was a case of 'only Amiga'

Now if you are stupid enough to put down the mutli-tasking kernal of Amiga because it doesn't magically fit interlaced HAM animations and complex word processor documents into 256kb well go and use a Win 95/98 PC where not only does the same thing not fit but their Kernal takes up much more memory AND it loses memory like a rusty sieve and needs constant daily reboots a decade after Kickstart/Workbench 1.2 to get the same program you just shut down to run again or print something etc etc!

[danwood]

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.

I couldn't disagree more, even "Mr Windows" Paul Thurott was an Amiga guy back then and admitted once on Windows Weekly podcast that the first time he used Windows 3.1 he thought it "was a joke, how can people seriously use this" (to paraphrase).

Workbench 3.x was light-years ahead of Windows 3.x, it really wasn't until 95 that it even felt remotely comparable.

[gertsy]

The first Amiga (to be known as the Amiga 1000) was special. Revolutionary.

Memory was the ceiling for multitasking for all PCs until relatively recently (Last 12 years) Because it was so expensive and usually programs were written to use all that a standard configuration supplied.
Windows 95 had 32 Bit preemptive multitasking with 32 Bit application protection. But you needed a lot of memory to run multiple programs. Luckily you couldn't install pizz poor marketing bullcrap onboard most MBs.