On Sat, 23 Mar 2013 19:41:08 +0000, Stephen wrote:

> On 23/03/2013 7:35 PM, Jim Henderson wrote:
>> The site I look at is the "officially unofficial" site - they seem to
>> be on target with the timeframes, but right now the upcoming series is
>> all "TBD".
> 
> Sometimes the BBC will tell you when the next broadcast will be. I do go
> to the "officially unofficial" site but I tried digging deeper. I did
> not find anything but that thought stuck. Anyway June is too long to
> wait. I will go away and invent a time machine.

That sounds like a plan.

Meantime, we've been listening to some series from the mid 90's.  We miss 
Willie.  And Humph.  Jack's getting the 'curmudgeon' routine down well, 
but nobody does it the way Humph did.

Jim

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On 23/03/2013 7:47 PM, Jim Henderson wrote:
> On Sat, 23 Mar 2013 19:41:08 +0000, Stephen wrote:

>> I will go away and invent a time machine.
>
> That sounds like a plan.
>

I decided just to render one, instead.
But I found a render on My HDD. So I suppose that I had better go and 
build the scene. To avoid any problems with causality.

> Meantime, we've been listening to some series from the mid 90's.  We miss
> Willie.

I never really took to Willie R. Too much of a middle class snob to my 
mind. He was funny, though.

> And Humph.  Jack's getting the 'curmudgeon' routine down well,
> but nobody does it the way Humph did.
>

That is Jack Dee's normal persona. He does well but Humph had years on 
the rest of the team and could look on everyone with the contempt of an 
adult with adolescents. He does very well but he is a youngster amongst 
giants. I think that in the long run they would have done better picking 
someone else as the chairman, someone with a different style. Maybe 
supper nannie. ;-)


-- 
Regards
     Stephen

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On Sat, 23 Mar 2013 20:23:19 +0000, Stephen wrote:

> On 23/03/2013 7:47 PM, Jim Henderson wrote:
>> On Sat, 23 Mar 2013 19:41:08 +0000, Stephen wrote:
> 
>>> I will go away and invent a time machine.
>>
>> That sounds like a plan.
>>
>>
> I decided just to render one, instead.
> But I found a render on My HDD. So I suppose that I had better go and
> build the scene. To avoid any problems with causality.

LOL

>> Meantime, we've been listening to some series from the mid 90's.  We
>> miss Willie.
> 
> I never really took to Willie R. Too much of a middle class snob to my
> mind. He was funny, though.

I don't know much about Willie other than that I found him funny on 
Clue. :)  But he often had one-liners that would just bring the house 
down, and even the other guys who were on the team at the time just don't 
have the comedic sense of timing that he did.

About the closest they come now to that kind of timing is in the game 
Word for Word, when (almost always as the second word), Tim will say 
"Pardon?" and then the other player will repeat what he said previously, 
to which Tim says "No, that was my word."

That one makes me chuckle every time, even though it's entirely 
predictable.

>> And Humph.  Jack's getting the 'curmudgeon' routine down well,
>> but nobody does it the way Humph did.
>>
>>
> That is Jack Dee's normal persona. He does well but Humph had years on
> the rest of the team and could look on everyone with the contempt of an
> adult with adolescents. He does very well but he is a youngster amongst
> giants. I think that in the long run they would have done better picking
> someone else as the chairman, someone with a different style. Maybe
> supper nannie. ;-)

Yeah, I've seen Jack on QI and a few other things (Kingdom, IIRC), and it 
does seem to be something even his characters have in common with him.  
But I don't know who else they could've picked - they couldn't "promote" 
any of the panelists because that just wouldn't work - that group of 
panelists works well together, even with the floating guest spot (which 
they really should just let Rob Broydon fill full time), but putting 
Barry or Graeme in charge (I couldn't see Tim doing it) would change the 
entire dynamic.

But I think Jack does his own thing - he doesn't try to be Humph, and 
that's a good thing.  I think if he did that, it wouldn't work at all.  
His demeanor is similar, but also distinctly different.

Jim

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Am 20.03.2013 22:21, schrieb Orchid Win7 v1:

> Naturally, I immediately asked myself whether you could build a cheap
> render farm out of these things. Having uttered the words aloud, at
> least one website about this subject must now exist. A trivial Google
> query verified this fact; there are indeed *several* such pages. They
> conclude that 100 Raspberries have roughly the same compute power is a
> £80 Intel Core i3. (100 x $35 = $3,500 >> £80)

As a side note, it might be worth mentioning that last time I checked, 
the Raspberry Pi's floating point math was still buggy (at least with 
Raspbian Linux; I suspect the hardware is ok, but the Pi's 
floating-point engine needs some software support for full IEEE standard 
conformance, and that part might still be wanting).

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Le 2013-03-21 18:03, Orchid Win7 v1 a écrit :
> If you run Debian (which has no special optimisations for such
> hardware), you find that it crawls along alarmingly slowly. I mean, slow
> to the point that you can't tell if the OS is actually functioning or
> not. Twenty minutes for GNOME to start!

What else did you expect from loading X11 with a heavy window manager on 
top of it on a system that only has 2 MB of ram?

You'd need at least 8MB to start X11 with a lightweight window manager 
without having it trip over itself in the process.


-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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On 24/03/2013 12:41 AM, Francois Labreque wrote:
> Le 2013-03-21 18:03, Orchid Win7 v1 a écrit :
>> If you run Debian (which has no special optimisations for such
>> hardware), you find that it crawls along alarmingly slowly. I mean, slow
>> to the point that you can't tell if the OS is actually functioning or
>> not. Twenty minutes for GNOME to start!
>
> What else did you expect from loading X11 with a heavy window manager on
> top of it on a system that only has 2 MB of ram?
>
> You'd need at least 8MB to start X11 with a lightweight window manager
> without having it trip over itself in the process.

Why? What does it need so much RAM for?

Also, I believe (not 100% sure) I had already added more RAM at this 
point. I think I had either 6MB or 10MB at the time.

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> I am afraid Andy is correct here (except for his prediction/observation
> that the PC almost caught up, any generation of a PC system was
> responsive when it came out of the box, but that stopped after you had
> used it for some time).

> The Amiga was a multiprocessor system with the GUI almost entirely
> handled by a coprocessor/firmware/hardware, the distinction is hard to
> make in this case.

I'm not sure what you're trying to say with this...

The mouse was drawn as a hardware sprite overlay, so moving the mouse 
pointer involves poking new coordinates into some video registers. This 
takes a handful of compute cycles, and is easily implemented by a single 
interrupt handler.

By default, dragging a window shows an outline. I believe there was an 
option somewhere to show full window contents while dragging. The Amiga 
had a dedicated chip for blitting areas of memory around, and 
particularly for blitting image data. That means the CPU just has to 
program a few parameters into this chip, and the window gets copied to 
its new location. Again, doesn't require much CPU power.

Several parts of the OS are stored in an on-board ROM. (In particular, 
the pre-emptive task scheduler, the file-system drivers and the GUI 
rendering code.) That doesn't mean you *have* to use these; it just 
means that if you do, they don't need to be loaded from disk.

> That meant that neither IO nor computations would
> interrupt the GUI; even if you completely overloaded the machine with
> computations and disk access the system was totally responsive visually.
> Many times my Amiga completely hung on something but I could still move
> the windows in real time, the mouse was functioning, even the buttons
> could be pressed.

Indeed. The Amiga was quite good at not doing that thing where 
everything stops responding until some event occurs.

(Having said that, without memory protection hardware, one rogue process 
could crash the entire machine. But on the first hand, buggy software 
was rare on that platform.)

> The only way a modern PC could even come close to such GUI performance
> is when one processor would be set aside for GUI only with no other
> tasks and even then the other processes could steal so many cycles that
> the GUI is slowed down markedly.

Well, my understanding is that modern graphics cards have hardware 
acceleration for graphical tasks too. So the situation shouldn't be too 
much different than how it was with the Amiga's custom hardware.

> You can now complain that the screen resolution of the Amiga was much
> less, that it was not a full implementation of a preemptive multiuser
> system, that it had no virtual memory etc.

640x768 for the highest video resolution, which *is* fairly limited. 
(But we're talking about a long-obsolete platform, after all.)

Pre-emptive: Yes. The OS is 100% pre-emptive. If some program goes into 
an infinite loop, you can kill it, and it *will* die. If some program 
tries to use all available RAM, it gets killed, and so forth.

Multi-user: No. Not even slightly. But hey, it's a home computer. It has 
no networking capabilities at all, so there's less call for multiple users.

Virtual memory: The CPU used lacks the necessary MMU hardware to 
implement either virtual addressing, memory protection or virtual 
memory. Later on you could buy add-on cards that included the MMU, and a 
few people made software that allows virtual memory.

(Adding memory protection would have broken applications. In particular, 
the OS messaging system fundamentally relies on zero-copy pointer 
passing, which doesn't work if each application lives in a different 
address space.)

> But that is all irrelevant to
> the observation that the Amiga had the best GUI response of any system I
> have seen yet.

Indeed.

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On Sat, 23 Mar 2013 20:41:39 -0400, Francois Labreque wrote:

> You'd need at least 8MB to start X11 with a lightweight window manager
> without having it trip over itself in the process.

That's not true - I know plenty of people who use 1-2 GB systems with FVWM 
or XFCE with no problems at all.

Heck, this desktop I'm using has only 6 GB of memory, and it runs GNOME3 
flawlessly.

Jim

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On Sun, 24 Mar 2013 13:23:19 -0400, Jim Henderson wrote:

> On Sat, 23 Mar 2013 20:41:39 -0400, Francois Labreque wrote:
> 
>> You'd need at least 8MB to start X11 with a lightweight window manager
>> without having it trip over itself in the process.
> 
> That's not true - I know plenty of people who use 1-2 GB systems with
> FVWM or XFCE with no problems at all.
> 
> Heck, this desktop I'm using has only 6 GB of memory, and it runs GNOME3
> flawlessly.

m-/

To self:  "8MB is not 8GB.  8MB is not 8GB"

Sorry, obviously I misread and thought you said 8 GB as a minimum 
requirement. ;)

Jim

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On 24/03/2013 05:24 PM, Jim Henderson wrote:
> Sorry, obviously I misread and thought you said 8 GB as a minimum
> requirement. ;)

0wned.

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>> without having it trip over itself in the process.
>
> Why? What does it need so much RAM for?

To do all the stuff it was doing that your Amiga wasn't :-)

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Le 2013-03-24 07:20, Orchid Win7 v1 a écrit :
> On 24/03/2013 12:41 AM, Francois Labreque wrote:
>> Le 2013-03-21 18:03, Orchid Win7 v1 a écrit :
>>> If you run Debian (which has no special optimisations for such
>>> hardware), you find that it crawls along alarmingly slowly. I mean, slow
>>> to the point that you can't tell if the OS is actually functioning or
>>> not. Twenty minutes for GNOME to start!
>>
>> What else did you expect from loading X11 with a heavy window manager on
>> top of it on a system that only has 2 MB of ram?
>>
>> You'd need at least 8MB to start X11 with a lightweight window manager
>> without having it trip over itself in the process.
>
> Why? What does it need so much RAM for?
>

Because the X11 specification is device-independent, so there's a few 
layers more required to deal with that, on top of it, it's a 
cleint/server environment, so it adds even more layers of code, whereas 
the AmigaOS UI is device-dependant and tied a few graphics chips with 
limited capabilities.


-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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On Mon, 25 Mar 2013 08:56:30 +0000, Orchid Win7 v1 wrote:

> On 24/03/2013 05:24 PM, Jim Henderson wrote:
>> Sorry, obviously I misread and thought you said 8 GB as a minimum
>> requirement. ;)
> 
> 0wned.

Nah, just misread. ;)

I'm no longer used to memory amounts being expressed in MB. :)

Jim

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>>> You'd need at least 8MB to start X11 with a lightweight window manager
>>> without having it trip over itself in the process.
>>
>> Why? What does it need so much RAM for?
>
> Because the X11 specification is device-independent, so there's a few
> layers more required to deal with that, on top of it, it's a
> cleint/server environment, so it adds even more layers of code, whereas
> the AmigaOS UI is device-dependant and tied a few graphics chips with
> limited capabilities.

That would explain why it needs more compute cycles, or why it doesn't 
utilise the Amiga's graphics acceleration hardware. It doesn't explain 
why it needs drastically more RAM.

Post a reply to this message

On 24-3-2013 14:05, Orchid Win7 v1 wrote:
>> I am afraid Andy is correct here (except for his prediction/observation
>> that the PC almost caught up, any generation of a PC system was
>> responsive when it came out of the box, but that stopped after you had
>> used it for some time).
>
>> The Amiga was a multiprocessor system with the GUI almost entirely
>> handled by a coprocessor/firmware/hardware, the distinction is hard to
>> make in this case.
>
> I'm not sure what you're trying to say with this...

That the Amiga managed to blur the distinction between these categories.

> The mouse was drawn as a hardware sprite overlay, so moving the mouse
> pointer involves poking new coordinates into some video registers. This
> takes a handful of compute cycles, and is easily implemented by a single
> interrupt handler.

IIRC it was not even that. I don't have my hardware books lying around 
anymore, but I think the horizontal and vertical motion of the mouse was 
determined by two bit gray codes. These two bits were directly connected 
to the video chip and the coordinates of the mouse were updated in 
hardware. No interrupt required.

> By default, dragging a window shows an outline. I believe there was an
> option somewhere to show full window contents while dragging. The Amiga
> had a dedicated chip for blitting areas of memory around, and
> particularly for blitting image data. That means the CPU just has to
> program a few parameters into this chip, and the window gets copied to
> its new location. Again, doesn't require much CPU power.
>
> Several parts of the OS are stored in an on-board ROM. (In particular,
> the pre-emptive task scheduler, the file-system drivers and the GUI
> rendering code.) That doesn't mean you *have* to use these; it just
> means that if you do, they don't need to be loaded from disk.
>
>> That meant that neither IO nor computations would
>> interrupt the GUI; even if you completely overloaded the machine with
>> computations and disk access the system was totally responsive visually.
>> Many times my Amiga completely hung on something but I could still move
>> the windows in real time, the mouse was functioning, even the buttons
>> could be pressed.
>
> Indeed. The Amiga was quite good at not doing that thing where
> everything stops responding until some event occurs.
>
> (Having said that, without memory protection hardware, one rogue process
> could crash the entire machine. But on the first hand, buggy software
> was rare on that platform.)

or a system call with a wrong parameter.
quoting from memory (from the OS library, that was documented, in 
contrast to some other OSes):
"note: this routine does no error checking. If you ask it to move the 
window to the end of the universe, it will. However, the resulting 
distortion of time and space that will result from this is in general 
not a pretty sight."

>> The only way a modern PC could even come close to such GUI performance
>> is when one processor would be set aside for GUI only with no other
>> tasks and even then the other processes could steal so many cycles that
>> the GUI is slowed down markedly.
>
> Well, my understanding is that modern graphics cards have hardware
> acceleration for graphical tasks too. So the situation shouldn't be too
> much different than how it was with the Amiga's custom hardware.

Then explain how I can sometimes see a window on a PC being refreshed 
top down? Oh, you said "shouldn't" not "isn't".

Another thing that I can't get my head around is the concept that you 
click on an object that is on screen when the click is handled, not on 
the one that is on-screen when you clicked.

>> You can now complain that the screen resolution of the Amiga was much
>> less, that it was not a full implementation of a preemptive multiuser
>> system, that it had no virtual memory etc.
>
> 640x768 for the highest video resolution, which *is* fairly limited.
> (But we're talking about a long-obsolete platform, after all.)
>
> Pre-emptive: Yes. The OS is 100% pre-emptive. If some program goes into
> an infinite loop, you can kill it, and it *will* die. If some program
> tries to use all available RAM, it gets killed, and so forth.

At the user level it was not fully preemptive. You had to do an explicit 
call to allow other programs to get some time too.

> Multi-user: No. Not even slightly. But hey, it's a home computer. It has
> no networking capabilities at all,

There were cards for that, but the basic machine did not have those.

> so there's less call for multiple users.

More of a design choice. But you had to assume all programs were 
friendly. Something you would not do today.

> Virtual memory: The CPU used lacks the necessary MMU hardware to
> implement either virtual addressing, memory protection or virtual
> memory. Later on you could buy add-on cards that included the MMU, and a
> few people made software that allows virtual memory.
>
> (Adding memory protection would have broken applications. In particular,
> the OS messaging system fundamentally relies on zero-copy pointer
> passing, which doesn't work if each application lives in a different
> address space.)
>
>> But that is all irrelevant to
>> the observation that the Amiga had the best GUI response of any system I
>> have seen yet.
>
> Indeed.


-- 
Women are the canaries of science. When they are underrepresented
it is a strong indication that non-scientific factors play a role
and the concentration of incorruptible scientists is also too low

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On Mon, 25 Mar 2013 21:40:17 +0000, Orchid Win7 v1 wrote:

> That would explain why it needs more compute cycles, or why it doesn't
> utilise the Amiga's graphics acceleration hardware. It doesn't explain
> why it needs drastically more RAM.

It's more complex software that has to run on more types of hardware.

More code = more memory required.

Jim

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> It's more complex software that has to run on more types of hardware.
>
> More code = more memory required.

Also at least on the Acorn/RiscOS a lot of the OS code was written in 
assembler. IME when I used a C compiler on that platform it sucked huge 
amounts of RAM and generated equally huge files, so much in fact that I 
needed to run it under a very buggy command-line-only virtual memory 
manager (I only had 4MB RAM and it needed 8MB). This may have also 
contributed to the larger RAM requirements of Linux.

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>> The mouse was drawn as a hardware sprite overlay, so moving the mouse
>> pointer involves poking new coordinates into some video registers. This
>> takes a handful of compute cycles, and is easily implemented by a single
>> interrupt handler.
>
> IIRC it was not even that. I don't have my hardware books lying around
> anymore, but I think the horizontal and vertical motion of the mouse was
> determined by two bit gray codes. These two bits were directly connected
> to the video chip and the coordinates of the mouse were updated in
> hardware. No interrupt required.

I'm pretty much certain that's not correct.

Under sufficiently heavy CPU load, the mouse pointer became slightly 
less responsive. There's no reason for that to happen if it's all 
implemented in hardware.

>> (Having said that, without memory protection hardware, one rogue process
>> could crash the entire machine. But on the first hand, buggy software
>> was rare on that platform.)
>
> or a system call with a wrong parameter.

Sure. The OS does little or no error checking - it's faster that way. So 
passing sufficiently invalid input to the OS will crash it. As will 
writing data to low-numbered memory addresses, or to addresses which 
don't exist, or addresses with are not aligned correctly. Or executing a 
non-existent op-code, for that matter. Any number of things which, in a 
protected-mode OS, would merely halt the offending process, would be an 
OS crash under AmigaOS.

>> Well, my understanding is that modern graphics cards have hardware
>> acceleration for graphical tasks too. So the situation shouldn't be too
>> much different than how it was with the Amiga's custom hardware.
>
> Then explain how I can sometimes see a window on a PC being refreshed
> top down? Oh, you said "shouldn't" not "isn't".

Clearly the graphics is being redrawn from scratch rather than being 
recopied from an off-screen buffer. That a piece of software doesn't 
take advantage of a feature doesn't mean the feature doesn't exist. It 
seems to me that the attitude of modern software is "hey, why bother 
optimising it? Just make the user buy more hardware."

> Another thing that I can't get my head around is the concept that you
> click on an object that is on screen when the click is handled, not on
> the one that is on-screen when you clicked.

Yeah, gotta love that.

>> Pre-emptive: Yes. The OS is 100% pre-emptive. If some program goes into
>> an infinite loop, you can kill it, and it *will* die. If some program
>> tries to use all available RAM, it gets killed, and so forth.
>
> At the user level it was not fully preemptive. You had to do an explicit
> call to allow other programs to get some time too.

What in the world makes you think that? If you run two programs that 
both try to use 100% CPU, they both end up getting approximately 50% 
CPU. (And everything else becomes fairly slow.) Unless you start 
altering priorities, anyway...

>> so there's less call for multiple users.
>
> More of a design choice. But you had to assume all programs were
> friendly. Something you would not do today.

Agreed.

Interestingly, there were several virus scanner programs for the Amiga, 
so clearly there were viruses around. I guess without the Internet, it's 
just that much harder to catch one...

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> Under sufficiently heavy CPU load, the mouse pointer became slightly
> less responsive. There's no reason for that to happen if it's all
> implemented in hardware.

On the Acorn there was no concept of CPU load as we have today - the CPU 
was always running at 100%. The OS just gave control to each running 
program in turn, when it had done all of them it started again. It was 
up to each program to give control back to the OS when it was done. If 
you didn't you got to use 100% CPU, which is what most full-screen games 
did and the default for simple programs.

IIRC the mouse pointer was updated by interrupt, so unless you 
deliberately disabled interrupts or wrote some buggy interrupt handler 
you never got any issue with pointer responsiveness.

> Clearly the graphics is being redrawn from scratch rather than being
> recopied from an off-screen buffer. That a piece of software doesn't
> take advantage of a feature doesn't mean the feature doesn't exist. It
> seems to me that the attitude of modern software is "hey, why bother
> optimising it? Just make the user buy more hardware."

Or rather, "it works fine on my 1 month old uber developer PC with 
nothing else running so i won't bother optimising it to work on a 5 year 
old pc".

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On 26/03/2013 11:20 AM, scott wrote:
>> Under sufficiently heavy CPU load, the mouse pointer became slightly
>> less responsive. There's no reason for that to happen if it's all
>> implemented in hardware.
>
> On the Acorn there was no concept of CPU load as we have today - the CPU
> was always running at 100%. The OS just gave control to each running
> program in turn, when it had done all of them it started again. It was
> up to each program to give control back to the OS when it was done. If
> you didn't you got to use 100% CPU, which is what most full-screen games
> did and the default for simple programs.

The AmigaOS was pre-emptive. There is no "yield" command; when your 
quantum is up, you get suspended and the next task gets to run. Nothing 
you can do about it.

(Well, no, I lie. You can ask the OS to turn off pre-emption. If you 
forget to tell it to turn pre-emption back on, basically the system 
hangs... Needless to say, this is a rarely-used feature. Except for 
games programming.)

> IIRC the mouse pointer was updated by interrupt, so unless you
> deliberately disabled interrupts or wrote some buggy interrupt handler
> you never got any issue with pointer responsiveness.

I'm almost certain AmigaOS drove the mouse pointer with a simple 
interrupt handler too.

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On 26/03/2013 11:20 AM, scott wrote:
> On the Acorn there was no concept of CPU load as we have today - the CPU
> was always running at 100%.

Interestingly, this is apparently how MS Access 97 works. It always uses 
100% CPU. Because, in 1997, busy-waiting was an acceptable design decision.

http://www.youtube.com/watch?v=dOV5WXISM24

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On 26-3-2013 11:25, Orchid Win7 v1 wrote:
> Interestingly, there were several virus scanner programs for the Amiga,
> so clearly there were viruses around. I guess without the Internet, it's
> just that much harder to catch one...

They were spread through the exchange of floppy disks I seem to remember 
from my Amiga days ;-)

Thomas

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On 26/03/2013 12:58 PM, Thomas de Groot wrote:
> On 26-3-2013 11:25, Orchid Win7 v1 wrote:
>> Interestingly, there were several virus scanner programs for the Amiga,
>> so clearly there were viruses around. I guess without the Internet, it's
>> just that much harder to catch one...
>
> They were spread through the exchange of floppy disks I seem to remember
> from my Amiga days ;-)

That's probably why I never saw an actual Amiga virus. I didn't have any 
friends.

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On 26-3-2013 11:25, Orchid Win7 v1 wrote:
>>> The mouse was drawn as a hardware sprite overlay, so moving the mouse
>>> pointer involves poking new coordinates into some video registers. This
>>> takes a handful of compute cycles, and is easily implemented by a single
>>> interrupt handler.
>>
>> IIRC it was not even that. I don't have my hardware books lying around
>> anymore, but I think the horizontal and vertical motion of the mouse was
>> determined by two bit gray codes. These two bits were directly connected
>> to the video chip and the coordinates of the mouse were updated in
>> hardware. No interrupt required.
>
> I'm pretty much certain that's not correct.

well, they were directly connected to Denise and there were hardware 
counters in Denise for X and Y.

> Under sufficiently heavy CPU load, the mouse pointer became slightly
> less responsive. There's no reason for that to happen if it's all
> implemented in hardware.

I can not find the logic circuit of Denise, so perhaps you are right and 
the contents of the register had to be fetched and put in the mouse 
sprite x and y.

>> At the user level it was not fully preemptive. You had to do an explicit
>> call to allow other programs to get some time too.
>
> What in the world makes you think that?

Because I have written programs at that level.
It is a great way to avoid a busy wait on an event in a high level 
language. Just check if your condition is met, if not pass control back 
to the scheduler. Repeat until you have something to do.

What I remember from those days is that a process could be interrupted 
by a higher level process, but user programs ran until they voluntary 
gave control back to the scheduler.*

> If you run two programs that
> both try to use 100% CPU, they both end up getting approximately 50%
> CPU. (And everything else becomes fairly slow.)

Because all programs you used behaved decent and passed control to the 
scheduler regularly? Remember we are thinking about a multitasking 
single user machine. There is no point in annoying the user by not 
giving other programs a change to run. There is not even a point in 
trying to get more than your fair share. But see the note below.

*) trying to google things, the wiki page on Exec_(Amiga) claims that 
linus once mistakingly said that AmigaOS was cooperative. In earlier 
versions of this page it *was* apparently considered cooperative, 
because google quotes a text that is no longer there. Another source 
says that the first version of AmigaOS was cooperative, implying that 
later versions weren't. Possibly I have been programming the earlier 
version and later versions indeed were fully preemptive, but the system 
calls still worked, so I did not notice the change.
For what I needed cooperative multitasking was exactly what I needed. 
E.g I had a multichannel dataacquisition running on a PC that was 
connected to the Amiga over a parallel port. I had one channel live in a 
separate screen** and a data analysis program that could use the same 
parallel connection to get the full data of a part of the recording. On 
the Amiga side I had several programs running, all cooperatively, 
including the parallel communication program (a sort of device driver 
but at user level). On the PC side I had to solve it with one big event 
loop.

**) for the non-amiga users: the Amiga was able to display several 
'screens' at the same time. Each with its own resolution and color 
depth. Transistions between screens were always at a horizontal line and 
the display line where that happened was handled by another custom chip. 
You could move a screen in front of another revealing or hiding as much 
as you wanted.

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On 26-3-2013 17:09, Orchid Win7 v1 wrote:
> On 26/03/2013 12:58 PM, Thomas de Groot wrote:
>> On 26-3-2013 11:25, Orchid Win7 v1 wrote:
>>> Interestingly, there were several virus scanner programs for the Amiga,
>>> so clearly there were viruses around. I guess without the Internet, it's
>>> just that much harder to catch one...
>>
>> They were spread through the exchange of floppy disks I seem to remember
>> from my Amiga days ;-)
>
> That's probably why I never saw an actual Amiga virus. I didn't have any
> friends.

LOL. I didn't meet any virus either but at work one guy was a huge 
collector of all kind of more or (mostly) less legal copies of Amiga 
software, and he regularly struggled with virus problems.

Thomas

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On 23/03/2013 8:48 PM, Jim Henderson wrote:
> On Sat, 23 Mar 2013 20:23:19 +0000, Stephen wrote:
>

>>
>> I never really took to Willie R. Too much of a middle class snob to my
>> mind. He was funny, though.
>
> I don't know much about Willie other than that I found him funny on
> Clue. :)  But he often had one-liners that would just bring the house
> down, and even the other guys who were on the team at the time just don't
> have the comedic sense of timing that he did.
>

I’m sorry, I thought that I had replied to you. I had a BSOD which wiped 
my own memory as well.

I grew up thinking Willie Rushton was the bee’s knees. Then, as I grew 
aware of the world, I found his right ling views unpalatable. I can’t 
hear recordings of him now without hearing a pompous, self regarding, 
smart arse, too full of his own self importance. But he was funny.

> About the closest they come now to that kind of timing is in the game
> Word for Word, when (almost always as the second word), Tim will say
> "Pardon?" and then the other player will repeat what he said previously,
> to which Tim says "No, that was my word."
>
> That one makes me chuckle every time, even though it's entirely
> predictable.
>

I thought that it was Graeme who did that.

>>> And Humph.  Jack's getting the 'curmudgeon' routine down well,
>>> but nobody does it the way Humph did.
>>>
>>>
>> That is Jack Dee's normal persona. He does well but Humph had years on
>> the rest of the team and could look on everyone with the contempt of an
>> adult with adolescents. He does very well but he is a youngster amongst
>> giants. I think that in the long run they would have done better picking
>> someone else as the chairman, someone with a different style. Maybe
>> supper nannie. ;-)
>
> Yeah, I've seen Jack on QI and a few other things (Kingdom, IIRC), and it
> does seem to be something even his characters have in common with him.
> But I don't know who else they could've picked - they couldn't "promote"
> any of the panelists because that just wouldn't work - that group of
> panelists works well together,

Indeed that is true.

> even with the floating guest spot (which
> they really should just let Rob Broydon fill full time),

I like the variety, one day they might get Nicolas Parsons.

> but putting
> Barry or Graeme in charge (I couldn't see Tim doing it) would change the
> entire dynamic.
>
> But I think Jack does his own thing - he doesn't try to be Humph, and
> that's a good thing.  I think if he did that, it wouldn't work at all.
> His demeanor is similar, but also distinctly different.
>

He does the best at an impossible job - filling Humph's boots.

-- 
Regards
     Stephen

Post a reply to this message

>> I'm pretty much certain that's not correct.
>
> well, they were directly connected to Denise and there were hardware
> counters in Denise for X and Y.
>
>> Under sufficiently heavy CPU load, the mouse pointer became slightly
>> less responsive. There's no reason for that to happen if it's all
>> implemented in hardware.
>
> I can not find the logic circuit of Denise, so perhaps you are right and
> the contents of the register had to be fetched and put in the mouse
> sprite x and y.

That was my understanding. The hardware may well be in the same chip, 
but it's under software control. (Like I said, it only takes a few 
op-codes to copy the X and Y coordinates from one pair of registers to 
another.)

>>> At the user level it was not fully preemptive. You had to do an explicit
>>> call to allow other programs to get some time too.
>>
>> What in the world makes you think that?
>
> Because I have written programs at that level.
> It is a great way to avoid a busy wait on an event in a high level
> language. Just check if your condition is met, if not pass control back
> to the scheduler. Repeat until you have something to do.
>
> What I remember from those days is that a process could be interrupted
> by a higher level process, but user programs ran until they voluntary
> gave control back to the scheduler.*

> *) trying to google things, the wiki page on Exec_(Amiga) claims that
> linus once mistakingly said that AmigaOS was cooperative. In earlier
> versions of this page it *was* apparently considered cooperative,
> because google quotes a text that is no longer there.

http://en.wikipedia.org/wiki/Exec_%28Amiga%29

"Exec is the multi-tasking kernel of AmigaOS. It enabled pre-emptive 
multitasking in as little as 256k of memory (as supplied with the first 
Amiga 1000s). Exec provided functionality for multi-tasking, memory 
allocation, interrupt handling and handling of dynamic shared libraries."

Sounds pre-emptive to me...

In particular, like several other fully pre-emptive systems, Exec 
provides Yield(), which lets you relinquish the rest of the current 
quantum if you wish. However, if you do not call this, a hardware 
interrupt causes Exec to perform a context switch to the next runnable 
task, in round-robin fashion, whether you ask for it or not.

Indeed, were Exec not pre-emptive, there would be no need for Forbid() 
and Permit(), which disable and enable pre-emption. (It's apparently 
used as a crude form of critical section.)

Now, if you mean that a lower-priority task can never run until all 
higher-priority tasks go to sleep, then yes, that's how the scheduler 
works. Usually the very high-priority tasks were things like the 
keyboard scan, which run for a tiny amount of time and then sleep again.

Post a reply to this message

On Wed, 27 Mar 2013 10:56:20 +0000, Stephen wrote:

> I’m sorry, I thought that I had replied to you. I had a BSOD which wiped
> my own memory as well.

:(

> I grew up thinking Willie Rushton was the bee’s knees. Then, as I grew
> aware of the world, I found his right ling views unpalatable. I can’t
> hear recordings of him now without hearing a pompous, self regarding,
> smart arse, too full of his own self importance. But he was funny.

That's a shame.  I feel kinda the same way about Jeremy Hardy, even 
though his leanings are similar to mine (but a bit more to the left).  
There are places where comedy and politics play well (and he uses this to 
great effect on The News Quiz), but other places where it doesn't belong.

>> About the closest they come now to that kind of timing is in the game
>> Word for Word, when (almost always as the second word), Tim will say
>> "Pardon?" and then the other player will repeat what he said
>> previously, to which Tim says "No, that was my word."
>>
>> That one makes me chuckle every time, even though it's entirely
>> predictable.
>>
> I thought that it was Graeme who did that.

That could be.  It's usually late when we're listening. :)

>> even with the floating guest spot (which they really should just let
>> Rob Broydon fill full time),
> 
> I like the variety, one day they might get Nicolas Parsons.

The variety is nice - it was fun to listen to a show from series <mumble> 
with Sandi Toksvig on it.  She made a joke about being proud to be one of 
a long list of female guests they'd had on the show, and it went over 
very well. :)

>> but putting Barry or Graeme in charge (I couldn't see Tim doing it)
>> would change the entire dynamic.
>>
>> But I think Jack does his own thing - he doesn't try to be Humph, and
>> that's a good thing.  I think if he did that, it wouldn't work at all.
>> His demeanor is similar, but also distinctly different.
>>
>>
> He does the best at an impossible job - filling Humph's boots.

That's the truth, no mistake about that.

Jim

Post a reply to this message

On 27/03/2013 9:42 PM, Jim Henderson wrote:
> On Wed, 27 Mar 2013 10:56:20 +0000, Stephen wrote:
>

>
> That's a shame.  I feel kinda the same way about Jeremy Hardy, even
> though his leanings are similar to mine (but a bit more to the left).
> There are places where comedy and politics play well (and he uses this to
> great effect on The News Quiz), but other places where it doesn't belong.
>

It is not a problem, nowadays. ;-)
True, some comedians have only one string to their bow. We had one, who 
died this month, whose act consisted of speaking as if his microphone 
was intermittent. He got thirty years of work out of it.


>>>
>> I thought that it was Graeme who did that.
>
> That could be.  It's usually late when we're listening. :)
>

I know, that late night interference on the shortwave radio can be 
dreadful. :-P


> The variety is nice - it was fun to listen to a show from series <mumble>
> with Sandi Toksvig on it.  She made a joke about being proud to be one of
> a long list of female guests they'd had on the show, and it went over
> very well. :)
>

That must have been the series when H&D did Hogmanay at the Big Hoose.



-- 
Regards
     Stephen

Post a reply to this message

On Thu, 28 Mar 2013 10:20:14 +0000, Stephen wrote:

> On 27/03/2013 9:42 PM, Jim Henderson wrote:
>> On Wed, 27 Mar 2013 10:56:20 +0000, Stephen wrote:
>> That's a shame.  I feel kinda the same way about Jeremy Hardy, even
>> though his leanings are similar to mine (but a bit more to the left).
>> There are places where comedy and politics play well (and he uses this
>> to great effect on The News Quiz), but other places where it doesn't
>> belong.
>>
> It is not a problem, nowadays. ;-)
> True, some comedians have only one string to their bow. We had one, who
> died this month, whose act consisted of speaking as if his microphone
> was intermittent. He got thirty years of work out of it.

Can't fault him for continuing to do something that works. :)

>>> I thought that it was Graeme who did that.
>>
>> That could be.  It's usually late when we're listening. :)
>>
> I know, that late night interference on the shortwave radio can be
> dreadful. :-P

It's pretty awful, I will admit. :)

>> The variety is nice - it was fun to listen to a show from series
>> <mumble>
>> with Sandi Toksvig on it.  She made a joke about being proud to be one
>> of a long list of female guests they'd had on the show, and it went
>> over very well. :)
>>
> That must have been the series when H&D did Hogmanay at the Big Hoose.

H&D?

Jim

Post a reply to this message

On 28/03/2013 5:28 PM, Jim Henderson wrote:
> On Thu, 28 Mar 2013 10:20:14 +0000, Stephen wrote:
>

>
> Can't fault him for continuing to do something that works. :)
>

You wouldn't say that if you had seen his act. ;-)
He was big in the 70's and 80's.
Norman Collier

)
>>>
>> That must have been the series when H&D did Hogmanay at the Big Hoose.
>
> H&D?
>
>

Hamish and Dougal.


-- 
Regards
     Stephen

Post a reply to this message

On Thu, 28 Mar 2013 20:10:11 +0000, Stephen wrote:

> On 28/03/2013 5:28 PM, Jim Henderson wrote:
>> On Thu, 28 Mar 2013 10:20:14 +0000, Stephen wrote:
>>
>>
> 
>> Can't fault him for continuing to do something that works. :)
>>
>>
> You wouldn't say that if you had seen his act. ;-)
> He was big in the 70's and 80's.
> Norman Collier

I may have to check that out. :)  I hadn't heard of him before.

>>> That must have been the series when H&D did Hogmanay at the Big Hoose.
>>
>> H&D?
>>
> Hamish and Dougal.

m-/  Of course, how did I miss that?

Maybe time for a relisten. :)

Jim

Post a reply to this message

On 27-3-2013 12:14, Orchid Win7 v1 wrote:

>>>> At the user level it was not fully preemptive. You had to do an
>>>> explicit
>>>> call to allow other programs to get some time too.
>>>
>>> What in the world makes you think that?
>>
>> Because I have written programs at that level.
>> It is a great way to avoid a busy wait on an event in a high level
>> language. Just check if your condition is met, if not pass control back
>> to the scheduler. Repeat until you have something to do.
>>
>> What I remember from those days is that a process could be interrupted
>> by a higher level process, but user programs ran until they voluntary
>> gave control back to the scheduler.*
>
>> *) trying to google things, the wiki page on Exec_(Amiga) claims that
>> linus once mistakingly said that AmigaOS was cooperative. In earlier
>> versions of this page it *was* apparently considered cooperative,
>> because google quotes a text that is no longer there.
>
> http://en.wikipedia.org/wiki/Exec_%28Amiga%29
>
> "Exec is the multi-tasking kernel of AmigaOS. It enabled pre-emptive
> multitasking in as little as 256k of memory (as supplied with the first
> Amiga 1000s). Exec provided functionality for multi-tasking, memory
> allocation, interrupt handling and handling of dynamic shared libraries."
>
> Sounds pre-emptive to me...

Either you did not understand what I wrote or you are from the younger 
generation that thinks just one source is enough. (a slightly belated 
happy birthday from me anyways)
I said that there are two positions to be found
1) that it *used to be* a cooperative multitasking system
2) that it *is* a pre-emptive multitasking system
You can count on it that I have seen that wiki-page. From that you can 
simply deduce that this did not settle the discussion for me. So quoting 
it as the definitive source that it has *always* been a pre-emptive 
system is a bit silly.


-- 
Women are the canaries of science. When they are underrepresented
it is a strong indication that non-scientific factors play a role
and the concentration of incorruptible scientists is also too low

Post a reply to this message

On 28/03/2013 11:56 PM, Jim Henderson wrote:
> On Thu, 28 Mar 2013 20:10:11 +0000, Stephen wrote:
>
>> Norman Collier
>
> I may have to check that out. :)  I hadn't heard of him before.
>

Or on the other hand, you may not want to check him out.
He is the epitome of watching weekend TV with your parents and wondering 
if you were from even the same species. ;-)

>>>> That must have been the series when H&D did Hogmanay at the Big Hoose.
>>>
>>> H&D?
>>>
>> Hamish and Dougal.
>
> m-/  Of course, how did I miss that?
>
> Maybe time for a relisten. :)
>
It is just that all those English voices sound the same. ;-)



-- 
Regards
     Stephen

Post a reply to this message

On Fri, 29 Mar 2013 10:09:02 +0000, Stephen wrote:

> On 28/03/2013 11:56 PM, Jim Henderson wrote:
>> On Thu, 28 Mar 2013 20:10:11 +0000, Stephen wrote:
>>
>>> Norman Collier
>>
>> I may have to check that out. :)  I hadn't heard of him before.
>>
>>
> Or on the other hand, you may not want to check him out.
> He is the epitome of watching weekend TV with your parents and wondering
> if you were from even the same species. ;-)

Is it one of those costume things? ;)

>>>>> That must have been the series when H&D did Hogmanay at the Big
>>>>> Hoose.
>>>>
>>>> H&D?
>>>>
>>> Hamish and Dougal.
>>
>> m-/  Of course, how did I miss that?
>>
>> Maybe time for a relisten. :)
>>
> It is just that all those English voices sound the same. ;-)

Yeah, that must be it. ;)

Jim

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On 29/03/2013 5:08 PM, Jim Henderson wrote:
> On Fri, 29 Mar 2013 10:09:02 +0000, Stephen wrote:
>
>> Or on the other hand, you may not want to check him out.
>> He is the epitome of watching weekend TV with your parents and wondering
>> if you were from even the same species. ;-)
>
> Is it one of those costume things? ;)
>

No, he pretended that he was a compere form a northern, working men's 
club (with a flat cap and an "Ee by gum". And a mic that kept stuttering.


>>>
>> It is just that all those English voices sound the same. ;-)
>
> Yeah, that must be it. ;)
>

Bound to be. :-)

-- 
Regards
     Stephen

Post a reply to this message

On Fri, 29 Mar 2013 17:57:14 +0000, Stephen wrote:

> On 29/03/2013 5:08 PM, Jim Henderson wrote:
>> On Fri, 29 Mar 2013 10:09:02 +0000, Stephen wrote:
>>
>>> Or on the other hand, you may not want to check him out.
>>> He is the epitome of watching weekend TV with your parents and
>>> wondering if you were from even the same species. ;-)
>>
>> Is it one of those costume things? ;)
>>
>>
> No, he pretended that he was a compere form a northern, working men's
> club (with a flat cap and an "Ee by gum". And a mic that kept
> stuttering.

Hmmm, that might work for us, but probably not. :)  Still, I'm sure 
there's a snippet on Youtube that I can check out if I can get up the 
motivation.

(BTW, I was quoting something with the 'costume thing' remark - I wasn't 
sure if you knew the reference or not)

Jim

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On 29/03/2013 9:53 PM, Jim Henderson wrote:
> Hmmm, that might work for us, but probably not.:)   Still, I'm sure
> there's a snippet on Youtube that I can check out if I can get up the
> motivation.
>

On your own head, be it.

> (BTW, I was quoting something with the 'costume thing' remark - I wasn't
> sure if you knew the reference or not)

Woosh!, I'm thinking "crinolines", here.


-- 
Regards
     Stephen

Post a reply to this message

On Fri, 29 Mar 2013 23:09:26 +0000, Stephen wrote:

> On 29/03/2013 9:53 PM, Jim Henderson wrote:
>> Hmmm, that might work for us, but probably not.:)   Still, I'm sure
>> there's a snippet on Youtube that I can check out if I can get up the
>> motivation.
>>
>>
> On your own head, be it.

:)

>> (BTW, I was quoting something with the 'costume thing' remark - I
>> wasn't sure if you knew the reference or not)
> 
> Woosh!, I'm thinking "crinolines", here.

John Cleese, actually - "How to Irritate People" - there's a sketch where 
Michael Palin and .... Oh, rather than try to explain it - this:

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

:)

Jim

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On Fri, 29 Mar 2013 19:20:46 -0400, Jim Henderson wrote:

> On Fri, 29 Mar 2013 23:09:26 +0000, Stephen wrote:
> 
>> On 29/03/2013 9:53 PM, Jim Henderson wrote:
>>> Hmmm, that might work for us, but probably not.:)   Still, I'm sure
>>> there's a snippet on Youtube that I can check out if I can get up the
>>> motivation.
>>>
>>>
>> On your own head, be it.
> 
> :)
> 
>>> (BTW, I was quoting something with the 'costume thing' remark - I
>>> wasn't sure if you knew the reference or not)
>> 
>> Woosh!, I'm thinking "crinolines", here.
> 
> John Cleese, actually - "How to Irritate People" - there's a sketch
> where Michael Palin and .... Oh, rather than try to explain it - this:
> 
> http://www.youtube.com/watch?v=fVmWlAHogfI
> 
> :)

That one makes me laugh because my parents are/were like that - I'd be 
watching the one programme I wanted to on a given evening, and that time 
was the time they wanted me to clean my room or whatever.  30 minutes 
later or an hour earlier would've been fine, but they always - without 
fail - would interrupt whatever it was I was watching to tell me I had to 
do something /right now/.

But the funnier one is the aeroplane sketch:

http://www.youtube.com/watch?v=xJSey8HRUhU

Jim

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