steveg@umd5.umd.edu (Steve Green) (05/02/90)
In article <8930@hubcap.clemson.edu> chrise@hubcap.clemson.edu (Chris Everhart) writes: ]In article <20499@boulder.Colorado.EDU>, judd@boulder.Colorado.EDU (Steve Judd) writes: ]> ]> Posting the second... ]> ]> Can somebody tell me about Multifinder for the Macs? A Mac fiend ]> that I know was telling me that the Mac has had multitasking for three years ]> by using Multifinder, on all models. I mean, this is a Mac, right? The bane ]> of all Amiga users? So, there has to be a catch, right? I'd hate to think ]> that all the great propaganda I've been hearing isn't true. ] ]There is indeed a catch. I have used the multifinder (on AMAX) before, and ]find it to be quite lame. It requires incredible amounts of memory and does ]not alow preemtive multitasking. In fact, I wouldn't call what it does ]multitasking at all. If you are running a word processor and something to ]do calculations for you, the computer will quit running the calculations ]program while you are using the word processor. This isn't multitasking at ]all. (if I'm wrong, someone correct me) I call it program swapping. The ]processor doesn't appear to be cycling time between the tasks. This kind of ]multitasking is the what people think of when they say "who needs it?" The ]Amiga is capable of running several programs SIMULTANEOUSLY. I can have my ]computations program drawing a graph, while I'm using my telecommunications ]software to read the news. And one doesn't stop for the other. As much as ]I like the MAC interface, it is the lack of true multitasking that ensures ]that I will never buy a MAC. You are a little confused about multitasking but the real point is about multifinder. From a long time Mac owners point of virew, Multifinder sucks. Surprised?? Multifinder is a lame excuse for multitasking BUT (here is comes) it does the job most of the time. 99% of the time that I use it, I have no complaints that it is not preemptive.. instead, and most important, I get upset at its lack of memory protection. I hate when a non-well behaved program trashes me out so bad that I have to reboot. I dont believe the Amiga has memory protection either?..?? For the most part, Multifinder works well but you do require lots of ram. ]Supposedly, there is a Unix ported from an old version running on the MAC now, ]but...who wants old stuff... Once again, you are underknowledged. AUX is a System V release 2 compliant but has always had alot of berkeleyisms. That is, alot of what is in R4 (AMIX) has been in AUX since it came out. As well, alot of new (non R2) stuff is part of AUX 2.0 eventhough it is still an R2 based system. I would be curoius to see a list of things that R4 (or AMIX) has that AUX 2.0 does not. I tend to believe that that list would be almost empty. ] ]Chris Everhart ]chrise@hubcap.clemson.edu -- What do these names have in common? Bob, Flo, Augie, Curtis, Gordon, Rick, Rhonda, Meep, Bismark, Skip, and Harry ...did I miss any?? steveg@umd5.umd.edu
new@udel.EDU (Darren New) (05/02/90)
In article <6460@umd5.umd.edu> steveg@umd5.umd.edu (Steve Green) writes: >upset at its lack of memory protection. I hate when a non-well behaved program >trashes me out so bad that I have to reboot. >I dont believe the Amiga has memory protection either?..?? >For the most part, Multifinder works well but you do require lots of ram. Well, since the Amiga was multitasking from day one, even without memory protection, fewer programs are ill-behaved. Vendors can't just say "Well, don't use multitasking" any more that Mac vendors can say "Well, don't use the mouse with this program." Few would buy a useful program that crashed and needed to be rebooted often. And since programs on Amy expect to be sharing with other programs, they tend to use less RAM also. On a Mac, it's not a problem to use all available memory (except under multifinder). -- Darren
UH2@psuvm.psu.edu (Lee Sailer) (05/02/90)
Multifinder has been around, but it offers a more limited flavor of multitasking than Amiga users are used to. 1. Amiga multi-tasking is "preemptive." This means that the OS can interrupt any program and start another. So, all programs are automatically multi-tasking (unless the programmer foes out of his way to make it otherwise). Multi-finder is "cooperative". This means that the programmer must insert statements into the code that say "OK. Give some other program a chance now". When this happens, if there are any others around, they'll get a turn. This means that older programs are very likely to hog the whole machine. 2. Mac multi-tasking requires much more memory, typically 2MB or more. Amiga multi-tasking is quite usable with 1MB. This is because, since the Amiga was designed with MT in mind from day one, there is a lot more sharing of memory resources. For example, two Mac programs in memory would each have there own complete copy of the window resizing code, while on the Amiga all programs would share that code. 3. The Amiga has more asynchronous processes (due to more custom chips). On the Mac, when info is being drawn to the screen, no other process can be executing because drawing is done by the main cpu. On the Amiga, when a task requests that something be drawn on the screen, a custom chip does part of the work, allowing the cpu to switch to some other task and do a little computing in the meanwhile. This is also true for I/O, printing, sound, voice, etc etc etc. In short, Multifinder is a great effort to tack something sort of like real multitasking onto a system that is basically a single-tasker, while Amiga multitasking is designed in from day one. Also, point out that while multifinder is "available," the vast majority of Macs don't have it installed. ALL Amigas have multitasking installed. So, though there are a few more Macs, there are more multitasking Amigas.
chrise@hubcap.clemson.edu (Chris Everhart) (05/02/90)
In article <10143@sdcc6.ucsd.edu>, cs163wed@sdcc10.ucsd.edu (see far) writes: > In article <8930@hubcap.clemson.edu> chrise@hubcap.clemson.edu (Chris Everhart) writes: > >all. (if I'm wrong, someone correct me) I call it program swapping. The > >processor doesn't appear to be cycling time between the tasks. This kind of > >multitasking is the what people think of when they say "who needs it?" The > >Amiga is capable of running several programs SIMULTANEOUSLY. I can have my > > ISn't the AMiga's multi-tasking program swapping? Unless you have > several amigas at once, you can never run programs simultaneously. > Amiga's multitasking only tricks you into thinking it is running > programs "simultaneously". > > After all, you get only one 68000 in an amiga, don't you? Yeah. Just go ahead and be picky. :-) Actually, I was referring to the virtual machine. Like most multitasking computers that will actually fit on your desk, the Amiga SIMULATES simultaneous program execution. I've had this beat into my head in one of my courses, and since that course dealt primarily with virtual machines, I spoke from that point of view. I also want to correct my previous statement when I said that Multifinder does not allow programs to run concurrently. It does, but one program is not allowed to interrupt another to gain the CPU. The advantage of this is that the application you are currently using does not get slowed down. The disadvantage is that the programs you have in the background will most likely be completely stopped (by something such as a wordprocessor which is almost always busy). The Amiga overcomes the problem of having your task get slowed down by allowing you to set priorities. You can make the computer run your task and no one elses if you need it. Is that better? :-) Chris Everhart chrise@hubcap.clemson.edu
chrise@hubcap.clemson.edu (Chris Everhart) (05/02/90)
In article <6845@jarthur.Claremont.EDU>, bgribble@jarthur.Claremont.EDU (Bill Gribble) writes: > WAIT!!! Don't kill him!!! He only said it out of stupidity - he's a > MAC owner!!! > > I enjoy good flame bait as much as the next fellow, but this is almost > ridiculous. I won't even include a word about the Amiga's multitasking - > I'll let someone else. I'm not a Mac owner. I just bought AMAX because I needed to use the laser printers here at school, and since they are only connected to the Apple-Talk network, I had no choice. :-) Chris Everhart chrise@hubcap.clemson.edu
johno@cbmvax.commodore.com (John Orr - CATS) (05/02/90)
In article <43785@iuvax.cs.indiana.edu> sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: > >Now, I'm no expert on the hardware of the Amiga, but I DO know that I can >be downloading a program AND writing a paper at the same time so I can >run 2 programs simultaneously. Maybe is is time-sharing like UNIX but I >don't really care. As far as I'm concerned (and care...) the Amiga DOES >multitask. >AMH > It is possible for Mac applications to be able to multitask well enough under multifinder to actually perform downloads and run a word processor at the same time, the only problem is that under the Mac OS, applications have to actively give up the CPU. Many Mac applications do not give up enough (or any) CPU time for other tasks to be able to do much of anything. The ability to multitask reasonably well is completely dependant upon the applications running at the moment. To multitask well on a Mac requires careful selection of applications. On the other hand, the Amiga's OS takes care of multitasking, so, in general, applications have little 'say' in whether or not they get swapped out or not (of course you realize this explanation is somewhat simplified). >* Andy Hartman | I'd deny half of this crap anyway!| /// >* Indiana University |-----------------------------------| /// >* | sl195091@silver.ucs.indiana.edu | \\\/// >* | AMHARTMA@rose.ucs.indiana.edu | \XX/ --John
es1@cunixb.cc.columbia.edu (Ethan Solomita) (05/02/90)
In article <8938@hubcap.clemson.edu> chrise@hubcap.clemson.edu (Chris Everhart) writes: >I also want to correct my previous statement when I said that Multifinder does >not allow programs to run concurrently. It does, but one program is not >allowed to interrupt another to gain the CPU. The advantage of this is that >the application you are currently using does not get slowed down. The >disadvantage is that the programs you have in the background will most likely >be completely stopped (by something such as a wordprocessor which is almost >always busy). The Amiga overcomes the problem of having your task get slowed >down by allowing you to set priorities. You can make the computer run your >task and no one elses if you need it. > >Is that better? :-) > >Chris Everhart >chrise@hubcap.clemson.edu One point that should be made is that most programs do not take up the full resources of the CPU, even a 68000. The 68000 has time to spare when you run your wordprocessor, so multitasking the Amiga way (as opposed to the Mac way) makes for more efficient use of the processor. -- Ethan Ethan Solomita: es1@cunixb.cc.columbia.edu "If Commodore had to market sushi they'd call it `raw cold fish'" -- The Bandito, inevitably stolen from someone else
tron1@tronsbox.UUCP (HIM) (05/03/90)
>Resp: 6 of 6 About: Re: Multifinder - Just the Facts, man. ><> [Steve Green] (*Masked*@umd5.umd.edu) >Once again, you are underknowledged. AUX is a System V release 2 compliant >but has always had alot of berkeleyisms. That is, alot of what is in R4 >(AMIX) >has been in AUX since it came out. As well, alot of new (non R2) stuff is >part of AUX 2.0 eventhough it is still an R2 based system. >I would be curoius to see a list of things that R4 (or AMIX) has that AUX 2.0 >does not. I tend to believe that that list would be almost empty. AUX is based on SYSVR2 , yes, it has the EQUIVILENT of many of the upgrades in R4 , but it does not , and can NEVER in it's current form , pass the SYSVR4 compatibility sweep. Leave it to Apple to talk about the "benefits" of a proprietary UNIX system in this day and age . Sheesh. Clairvoyant Brain Boffs Predict: Jehova's Witness Ewoks Will Avoid Lemons. ********[ Xanadu Enterprises Inc. Amiga & Unix Software Development]******** * Kenneth J. Jamieson | "Far beyond these castle walls, where the distant * * uunet!tronsbox!tron1 | harbor meets the sky, there the battles raged * * All origional text | like hell, and every dove had lost it's will * * Copr 1990 by me. | to fly......." Styx - These Castle Walls * *_____________________/ \__________________________________________________* * NONE of the opinions represented here are endorsed by either Xanadu * * Xanadu Enterpises or it's clients, AT&T Bell Labs or others. * ****[ The Romantic Encounters BBS 201-759-8450(2400) / 201-759-8568(PEP)****
mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) (05/03/90)
In article <11250@cbmvax.commodore.com> johno@cbmvax (John Orr - CATS) writes: >It is possible for Mac applications to be able to multitask well >enough under multifinder to actually perform downloads and run a word >processor at the same time, the only problem is that under the Mac OS, >applications have to actively give up the CPU. Many Mac applications >do not give up enough (or any) CPU time for other tasks to be able to >do much of anything. Very few Mac applications refuse to yield the CPU (unless they have your permission -- some decompression programs have such an option). Apple pulled a sneaky one to get MultiFinder to work. The switch from program to program (task switch) happens when GetNextEvent or WaitNextEvent is called. Since these routines are crucial in almost all applications, multitasking works smoothly. True the Amiga does this better with multitasking built-in from the start, but the Mac does a good job for just a minor add-on to the OS. -Michael -- Michael Niehaus UUCP: <backbones>!{iuvax,pur-ee}!bsu-cs!mithomas Apple Student Rep ARPA: mithomas@bsu-cs.bsu.edu Ball State University AppleLink: ST0374 (from UUCP: st0374@applelink.apple.com)
ddev@wam.umd.edu (Don DeVoe) (05/03/90)
In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: >In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: >> In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: >> >>> >>>ISn't the AMiga's multi-tasking program swapping? Unless you have >>>several amigas at once, you can never run programs simultaneously. >>>Amiga's multitasking only tricks you into thinking it is running >>>programs "simultaneously". >>> >>>After all, you get only one 68000 in an amiga, don't you? >> > >Youre right, Andy. >This drongo doesn't know the difference between multitasking and parallel >processing. Tell us, just what is the difference? In a strict sense, you can't have (true) multitasking without multiple processors...anything else is just program swapping; multitasking is implicitly denied in a single processor system. And just what is a drongo, anyway? -- Don DeVoe "Every jumbled pile of person has a thinking part that wonders ddev@epsl.umd.edu what the part that isn't thinking isn't thinking of" -TMBG
jep@mtiame.oz (Jesper Peterson) (05/03/90)
> >Once again, you are underknowledged. AUX is a System V release 2 compliant >but has always had alot of berkeleyisms. SVR2 + berkeley = proprietary = big trouble. Write anything even remotely clever for this and it becomes a real headache to port "back" to standard SYSV. >I would be curoius to see a list of things that R4 (or AMIX) has that AUX 2.0 >does not. I tend to believe that that list would be almost empty. Streams? Jesper. -- ACSnet: jep@mtiame.mtia.oz "This lottery is my bathroom." UUCP: ...!uunet!munnari!mtiame.oz!jep - Peg (Married with Children) PHONE: (03) 699-1022
BAXTER_A@wehi.dn.mu.oz (05/03/90)
In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: > In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: > >> >>ISn't the AMiga's multi-tasking program swapping? Unless you have >>several amigas at once, you can never run programs simultaneously. >>Amiga's multitasking only tricks you into thinking it is running >>programs "simultaneously". >> >>After all, you get only one 68000 in an amiga, don't you? > > >>-- >>What is the Final Outcome for China's current situation? >>In China, 1992, (Lee Huan of) Taiwan will liberate Mainland! > > Now, I'm no expert on the hardware of the Amiga, but I DO know that I can > be downloading a program AND writing a paper at the same time so I can > run 2 programs simultaneously. Maybe is is time-sharing like UNIX but I > don't really care. As far as I'm concerned (and care...) the Amiga DOES > multitask. > Youre right, Andy. This drongo doesn't know the difference between multitasking and parallel processing. Regards Alan
doug@fuji.ctc.contel.com (05/03/90)
You can argue definitions with someone else, but if you want to understand
the differences, the following may help ...
Program Swapping -- An attribute that describes an OS that voluntarily
or involuntarily suspends of execution of one task (application) for
execution of another task (application), where there is no formal
priority between tasks, and task swapping often requires user interaction.
Example -- appA is running, user starts appB; so AppA is suspended
while AppB runs.
User selects appA; so AppB is suspended and AppA picks up
where it left off.
Example -- appA runs awhile and voluntarily releases the cpu, so
AppB can continue
Multitasking -- An attribute of an OS similar to Program Swapping,
except the cpu time is formally considered a resource that is "shared"
between tasks (applications), and there is some formal priority between
tasks, such that cpu time is delved out to applications without user
interaction, or task (application) behavior.
Example -- appA and appB have the same priority. The OS runs a
little of appA, then
runs a little of appB, then a little of appA, then B, A, B, A, B, ...
Note- if the computer is fast enough, then both
applications will appear
to be running at the same time, and neither application explicitly
releases the cpu.
Multiprocessing -- An attribute of a computer system, or an operating
system that allows two or more processors (usually cpus) executing
instructions at the same time. Note- One could have a
multiprocessing, single tasking computer (i.e. all processors working
on the same application, together)
'Haidsteveg@umd5.umd.edu (Steve Green) (05/03/90)
In article <222@mtiame.oz> jep@mtiame.oz (Jesper Peterson) writes:
]>
]>Once again, you are underknowledged. AUX is a System V release 2 compliant
]>but has always had alot of berkeleyisms.
]
]SVR2 + berkeley = proprietary = big trouble.
That is a totally unfounded statement. AT&T System V relase 4 has includes
some of the very same berkleyisms that AUX does.
Wow, SVR4 is not proprietary..??.. Dont tell AT&T that! :-)
]Write anything even remotely clever for this and it becomes a real
]headache to port "back" to standard SYSV.
No more of a headache than it would be to "port" from SVR4 or BSD back to SVR2.
]>I would be curoius to see a list of things that R4 (or AMIX) has that AUX 2.0
]>does not. I tend to believe that that list would be almost empty.
]
]Streams?
AUX has streams.
]Jesper.
]
]--
]ACSnet: jep@mtiame.mtia.oz "This lottery is my bathroom."
]UUCP: ...!uunet!munnari!mtiame.oz!jep - Peg (Married with Children)
]PHONE: (03) 699-1022new@udel.EDU (Darren New) (05/03/90)
In article <1990May3.042500.18758@wam.umd.edu> ddev@wam.umd.edu (Don DeVoe) writes: >>This drongo doesn't know the difference between multitasking and parallel >>processing. > >Tell us, just what is the difference? In a strict sense, you can't have >(true) multitasking without multiple processors...anything else is just >program swapping; multitasking is implicitly denied in a single processor >system. And just what is a drongo, anyway? The difference is this: Multitasking is when two or more tasks are run concurrently. Parallel processing is when two or more tasks run simultaneously. (assuming you mean MIMD. A better one may be "two or more instructions running concurrently.) The difference is this: Simultaneous means "at the same time". Concurrent means "Another may start between the time the first starts and the time the first ends." Hence, MS-DOS (ignoring TSRs...) is single processing, single tasking. The Mac OS (under multifinder) is nonpreemptively (sp?) multitasking. The AmigaOS is premptively multitasking and parallel processing (via Agnus). Unix is multitasking and multiprocessing (where "process" is taken in the computer-science sense). The difference between multiprocessing and multitasking is the difference between a Unix process crashing and an AmigaDOS task crashing: address spaces. Unix processes cannot share address spaces while AmigaDOS processes must. (Unix shared memory segments are shared with the kernel and are a special case I'm ignoring here.) I hope this clears up some terminology. -- Darren
seanc@pro-party.cts.com (Sean Cunningham) (05/03/90)
In-Reply-To: message from bgribble@jarthur.Claremont.EDU Since the guy owns a Mac, HOW could he even KNOW what true multitasking is...he certainly isn't speaking from experience, unless that is, he used another machine...like...an Amiga. Multifinder's nothing more than a TSR utility. //////////////////////////////////////////////////////////////////////////// UUCP: ...!crash!pnet01!pro-party!seanc | ARPA: !crash!pnet01!pro-party!seanc@nosc.mil | " Fanatics have their INET: seanc@pro-party.cts.com | dreams, wherewith they | weave a paradise for RealWorld: Sean Cunningham | a sect. " Voice: (512) 994-1602 PLINK: ce3k* | -Keats | Call C.B.A.U.G. BBS (512) 883-8351 w/SkyPix | B^) VISION GRAPHICS B^) \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
eas3714@ultb.isc.rit.edu (E.A. Story) (05/03/90)
In article <6845@jarthur.Claremont.EDU> bgribble@jarthur.Claremont.EDU (Bill Gribble) writes: >In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: > >>ISn't the AMiga's multi-tasking program swapping? Unless you have >>several amigas at once, you can never run programs simultaneously. >>Amiga's multitasking only tricks you into thinking it is running >>programs "simultaneously". > >>After all, you get only one 68000 in an amiga, don't you? > >>>Chris Everhart >>>chrise@hubcap.clemson.edu > >WAIT!!! Don't kill him!!! He only said it out of stupidity - he's a > MAC owner!!! Well, I'm not completely sure, but I think multifinder does multitask with the right programs. You see, under Amiga's OS the task switching is basically transparent.. the kernal takes care of switching processes and giving each program its proper timeshare. Under Multifinder, each program is responsible for allowing other programs to run... so consequently, if a program wasn't originally written for multifiner, multifinder will only switch programs.. not giving the non-active ANY time. if it was, the program should have been programmed to give any non-active programs some sort of time to do something. NOTE: I could be totally wrong! I haven't really even used Multifinder that much! This is gathered from what I've read on the net .. ----Ezra Ezra Story : "I HATE .sig files!" eas3714@ultb.isc.rit.edu
unhd (Jason W Nyberg) (05/04/90)
In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: >In article <8930@hubcap.clemson.edu> chrise@hubcap.clemson.edu (Chris Everhart) writes: >>In article <20499@boulder.Colorado.EDU>, judd@boulder.Colorado.EDU (Steve Judd) writes: >>> >>> Posting the second... >>There is indeed a catch. I have used the multifinder (on AMAX) before, and >>find it to be quite lame. It requires incredible amounts of memory and does >>not alow preemtive multitasking. In fact, I wouldn't call what it does >>multitasking at all. If you are running a word processor and something to >>do calculations for you, the computer will quit running the calculations >>program while you are using the word processor. This isn't multitasking at >>all. (if I'm wrong, someone correct me) I call it program swapping. The >>processor doesn't appear to be cycling time between the tasks. This kind of >>multitasking is the what people think of when they say "who needs it?" The >>Amiga is capable of running several programs SIMULTANEOUSLY. I can have my > >ISn't the AMiga's multi-tasking program swapping? Unless you have No. It is true multi-tasking. >several amigas at once, you can never run programs simultaneously. >Amiga's multitasking only tricks you into thinking it is running >programs "simultaneously". > True, It does trick you into thinking that it is running more than one process simultaneously, but it does run more than one process at any given moment, exactly like VAXs, Suns, etc. The thing is, the user doesn't even notice, isn't even involved, in the context switching of the processor. And, even on a vanilla Amiga, you can run many applications together without even noticing a slowdown of the system. Ask an EE professor what an interrupt is, and how it relates to multitasking... >After all, you get only one 68000 in an amiga, don't you? One's all you need. -Jason Nyberg
swarren@convex.com (Steve Warren) (05/04/90)
In article <1990May3.042500.18758@wam.umd.edu> ddev@wam.umd.edu (Don DeVoe) writes: >In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: >>In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: ... >>Youre right, Andy. >>This drongo doesn't know the difference between multitasking and parallel >>processing. > >Tell us, just what is the difference? In a strict sense, you can't have >(true) multitasking without multiple processors...anything else is just >program swapping; multitasking is implicitly denied in a single processor >system. And just what is a drongo, anyway? Multitasking refers to multiple tasks being performed but does not imply that they are simultaneously processed by multiple processors. Multiprocessing refers to the actual processing and does mean that the tasks are processed simultaneously. This confusion is a common mistake. Please do not continue to insist that multitasking==multiprocessing. There are two different terms because they are two different concepts. -- --Steve DISCLAIMER: All opinions are my own (I don't speak for Convex) ---------------------------------------------------------------------------- {uunet,sun}!convex!swarren; swarren@convex.COM
carpent@SRC.Honeywell.COM (Todd Carpenter) (05/04/90)
PLEASE CONTINUE THIS DISCUSSION ELSEWHERE. Geez! This topic comes up every few months. CUT IT OUT! We have quite enough bandwidth wasted anyway, and you idiots are only increasing it. And for those of us who UUCP things down to our amiga, we prefer to read about Amiga stuff in the Amiga newsgroup. Not these incessant computer wars. This is an Amiga newsgroup. Keep it that way. Lest someone whine at me for wasting bandwidth (which I am), I do have a real question: Has anyone used SuperPlan? Do you have any idea how it compares to Excel? -TC
ckp@grebyn.com (Checkpoint Technologies) (05/04/90)
In article <1990May3.042500.18758@wam.umd.edu> ddev@wam.umd.edu (Don DeVoe) writes: >In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: >>Youre right, Andy. >>This drongo doesn't know the difference between multitasking and parallel >>processing. > >Tell us, just what is the difference? In a strict sense, you can't have >(true) multitasking without multiple processors...anything else is just >program swapping; multitasking is implicitly denied in a single processor >system. And just what is a drongo, anyway? It's all a question of semantics. As far as I understand: "Parallel processing" has come to mean more than one CPU of like architecture cooperating to solve a single job. Several linked Transputers may be considered "parallel processing" if they are cooperating to run one program (which typically Helios doesn't do I understand). "Multi-tasking" is when a single CPU is shared among several jobs, each of which has a current "context" which is preserved by the OS, by whatever means. By this definition I consider Multi-Finder "multi-tasking", but before you flame me, read on... "Pre-emtive" multi-tasking means that the single CPU can be taken from one job to another at any arbitrary point in the first job; it happens that the Amiga has Exec functions to disable and enable pre-emption (Forbid and Permit), but most pre-emptive multi-tasking OS'es don't, they use semaphores. "Co-processing" and "Co-processors" indicate multiple processors of dislike architectures; usually each co-processor is designed to handle a particular kind of work efficiently, like floating point math, IO tasks, or graphics, and may not be powerful enough to be considered general-purpose CPUs, but they might. The Z80 in the A2090 and the 6502's in the Max IIfx would be co-processors. I guess I don't consider a simple DMA channel as a co-processor, though some may not agree with me. OK, that means the Mac with Multi-finder is *not* parallel processing, *is* multi-tasking but *not* pre-emptive, and *may* have co-processors if you pay enough (the IIfx, the 8/24 GC color card, and the 68881/2 math chip). The Amiga is *not* parallel processing, *is* pre-emptive multi-tasking, and *does* have co-processors and DMA. -- First comes the logo: C H E C K P O I N T T E C H N O L O G I E S / / \\ / / Then, the disclaimer: All expressed opinions are, indeed, opinions. \ / o Now for the witty part: I'm pink, therefore, I'm spam! \/
sysop@tlvx.UUCP (SysOp) (05/04/90)
In article <10143@sdcc6.ucsd.edu>, cs163wed@sdcc10.ucsd.edu (see far) writes: > In article <8930@hubcap.clemson.edu> chrise@hubcap.clemson.edu (Chris Everhart) writes: > >In article <20499@boulder.Colorado.EDU>, judd@boulder.Colorado.EDU (Steve Judd) writes: > >> > >> Posting the second... > >There is indeed a catch. I have used the multifinder (on AMAX) before, and > >find it to be quite lame. It requires incredible amounts of memory and does > >not alow preemtive multitasking. In fact, I wouldn't call what it does > >multitasking at all. If you are running a word processor and something to > >do calculations for you, the computer will quit running the calculations > >program while you are using the word processor. This isn't multitasking at > >all. (if I'm wrong, someone correct me) I call it program swapping. The > >processor doesn't appear to be cycling time between the tasks. This kind of > >multitasking is the what people think of when they say "who needs it?" The > >Amiga is capable of running several programs SIMULTANEOUSLY. I can have my From what I've heard about multi-finder (very little), perhaps the word processor was poorly-written in some area. It should have occasionally relinquished control. (Inbetween keystrokes, one would think! Geesh!) > > ISn't the AMiga's multi-tasking program swapping? Unless you have Argh, no, he was talking about something different! When he meant program swapping, he meant that when he started using the word processor, the other program stopped dead, and waited until he went back, even if that were MINUTES later! There was no appearance of running simultaneously with the situation he mentioned. There have been programs for various machines that, for instance, swap the contents of memory to disk, then load another program that was saved in progress, and resumed execution. I would call that "program swapping". > several amigas at once, you can never run programs simultaneously. > Amiga's multitasking only tricks you into thinking it is running > programs "simultaneously". This is what people mean by "multi-tasking." The Amiga multitasking is "preemptive" in that (ok I'm going to simplify this terribly) a program only gets a small amount of time, then it's removed from the CPU, and the next program in the ready queue is run, but only for a short while. The program itself doesn't know when it'll be kicked off the CPU, but since it's environment is saved and restored, it doesn't have to know. Each duration is small, so on the whole, it looks like they're all running simultaneously. (BTW, Transactor had a programs for the C-64 that both "program swapped" and "multitasked" BASIC programs. Heh. Not too useful, but cute.) Another way to multi-task is to allow the program to take the CPU for as long as it wants, and only let other programs have the CPU whenever they're done. So, things seem to multi-task when all programs are nice, and when one isn't nice, it hogs it all. Meanwhile, it would be hard to judge just how much time each program gets; do they get a fair amount? Anyway, programs will appear to run simultaneously so long as one (or more) programs aren't real hogs. > > After all, you get only one 68000 in an amiga, don't you? Then explain why other OS's running on other one-CPU machines use the term "multi-tasking"? :-) > > > >Chris Everhart > >chrise@hubcap.clemson.edu > ...
jep@mtiame.oz (Jesper Peterson) (05/04/90)
In article <6465@umd5.umd.edu> steveg@umd5.umd.edu (Steve Green) writes: >In article <222@mtiame.oz> jep@mtiame.oz (Jesper Peterson) writes: >]SVR2 + berkeley = proprietary = big trouble. > >That is a totally unfounded statement. AT&T System V relase 4 has includes >some of the very same berkleyisms that AUX does. some != all > >Wow, SVR4 is not proprietary..??.. Dont tell AT&T that! :-) Proprietary in the sense that only Apple use it. SVR4 is used across more hardware platforms. > >]Write anything even remotely clever for this and it becomes a real >]headache to port "back" to standard SYSV. > >No more of a headache than it would be to "port" from SVR4 or BSD back to SVR2. I was referring to porting "forward". plain SVR2 -> SVR4 is easy, AUX->SVR4 is not so. Your wording is appropriate when you say BSD *back* to SVR2. I used to work on a BSD (actually SunOS, proprietary again, but some of this is now in SVR4, this argument is getting complicated, not to mention pointless :-) now I work on SVR2 (soon R3). Porting my favourite programs to this system? ARGH! ( and no filename completion!!! ) > >]>I would be curoius to see a list of things that R4 (or AMIX) has that AUX 2.0 >]>does not. I tend to believe that that list would be almost empty. >] >]Streams? > >AUX has streams. Just asking. End of my story (e-mail please). Jesper. -- ACSnet: jep@mtiame.mtia.oz "This lottery is my bathroom." UUCP: ...!uunet!munnari!mtiame.oz!jep - Peg (Married with Children) PHONE: (03) 699-1022
matth@extro.ucc.su.OZ.AU (Matthew Hannigan) (05/04/90)
In article <1990May3.042500.18758@wam.umd.edu> ddev@wam.umd.edu (Don DeVoe) writes: >In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: >>In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: >>> In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: >>>> >>>>ISn't the AMiga's multi-tasking program swapping? Unless you have >>>>several amigas at once, you can never run programs simultaneously. >>>>Amiga's multitasking only tricks you into thinking it is running >>>>programs "simultaneously". >>>> >>>>After all, you get only one 68000 in an amiga, don't you? >> >>Youre right, Andy. >>This drongo doesn't know the difference between multitasking and parallel >>processing. > >Tell us, just what is the difference? In a strict sense, you can't have >(true) multitasking without multiple processors...anything else is just >program swapping; multitasking is implicitly denied in a single processor >system. And just what is a drongo, anyway? >-- >Don DeVoe "Every jumbled pile of person has a thinking part that wonders >ddev@epsl.umd.edu what the part that isn't thinking isn't thinking of" -TMBG Yes, you can get true multi-tasking on a single processor machine. Just about every multi-tasking computer up to now has had a single main processor. I suggest anybody really interested in this subject reads a text, say "Tanenbaum : OS - Design and Implementation" before contributing on this thread. Also, the use of the word 'swapping' has other connotations when discussing OS's - the word(s) you're after is probably 'task-switching'. This subject seems to come up (too) frequently on c.s.amiga. 'Drongo' is a bit of Australian slang. I guess a close definition would be 'someone not afraid of showing their ignorance' :-) Regards, -Matt
BAXTER_A@wehi.dn.mu.oz (05/04/90)
In article <1990May3.042500.18758@wam.umd.edu>, ddev@wam.umd.edu (Don DeVoe) writes: > In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: >>In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: >>> In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: >>> >>>> >>>>ISn't the AMiga's multi-tasking program swapping? Unless you have >>>>several amigas at once, you can never run programs simultaneously. >>>>Amiga's multitasking only tricks you into thinking it is running >>>>programs "simultaneously". >>>> >>>>After all, you get only one 68000 in an amiga, don't you? >>> >> >>Youre right, Andy. >>This drongo doesn't know the difference between multitasking and parallel >>processing. > > Tell us, just what is the difference? In a strict sense, you can't have > (true) multitasking without multiple processors...anything else is just > program swapping; multitasking is implicitly denied in a single processor > system. And just what is a drongo, anyway? This is a problem of semantics. Some words mean a thing. Now no matter how hard someone may want them to mean something else, they don't until a whole bunch of people get to gether and have a common, new meaning of the words. In a stict sense, multitasking is the process of maintaining more than one task concurrently. Not necessarily actually processing data from each of the tasks similtaneously, just maintaining them. Because of the way it is achieved on a mainframe, people have come to expect pre-emptive task switching, but this is not an essential feature. Yes, the mac multitasks. Not well, but it does. Parallel processing involves the concurrent use of more than one processor. The words imply a number of things. I am not sure to what extent they are essential, but most people expect a real parallel machine to have multiple processors of the same type that are networked in such a way that any processor can send a result to any other using address and relay system similar to that on networked BBS's. Lots of people also describe a computer with co-processors as "parallel processing" which is strictly correct, but largely not what is ment when the words are used in the literature. A 'drongo' is a cheerful, friendly idiot. It is a generic term of abuse used in Australia amongst friends. It is roughly equivalent to the Australian use of the word "bastard", which our prime minister uses with great effect. Regards Alan > > -- > Don DeVoe "Every jumbled pile of person has a thinking part that wonders > ddev@epsl.umd.edu what the part that isn't thinking isn't thinking of" -TMBG
tulloh@cantor.ACA.MCC.COM (Robert Tulloh) (05/05/90)
In article <1990May3.042500.18758@wam.umd.edu>, ddev@wam.umd.edu (Don DeVoe) writes: > In article <7416@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes: > >In article <43785@iuvax.cs.indiana.edu>, sl195091@silver.ucs.indiana.edu (Andy Hartman) writes: > >> In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: > >> > >>> > >>>ISn't the AMiga's multi-tasking program swapping? Unless you have > >>>several amigas at once, you can never run programs simultaneously. > >>>Amiga's multitasking only tricks you into thinking it is running > >>>programs "simultaneously". > >>> > >>>After all, you get only one 68000 in an amiga, don't you? > >> > > > >Youre right, Andy. > >This drongo doesn't know the difference between multitasking and parallel > >processing. > > Tell us, just what is the difference? In a strict sense, you can't have > (true) multitasking without multiple processors...anything else is just > program swapping; multitasking is implicitly denied in a single processor > system. And just what is a drongo, anyway? > > > -- > Don DeVoe Perhaps it depends on your definition of multitasking. So here is one for your approval/disapproval... Multitasking is the process by which an O/S can manage one or more processes running concurrently, but never any two programs executing at the same time. Each process gets a timeslice of CPU time with the size of the slice dependent on task priorities, the number of tasks executing, and the nature of the executing tasks (some tasks simply don't need to execute when it is their turn). So, you don't need more than one CPU to multitask. True multitasking implies the O/S is controlling who gets to execute when, not the programs that are running under it. Thus, on a multitasking system, you don't have to write programs which have to worry about giving up the CPU to other programs since you know that the O/S will handle this little job for you (<grin> :-). I contend that with multiple processors you then have distributed or parallel processing (no, I don't mean these are the same thing). These environments can also be multitasking (and they usually are!). Rob Tulloh MCC, Deductive Computing | ARPA : tulloh@mcc.com | Phone: (512) 338-3704 3500 West Balcones Center Dr. | UUCP : ...!cs.utexas.edu!hippo!cantor!tulloh Austin, TX 78759 | GENIE: R.TULLOH -- MCC, Deductive Computing | ARPA: tulloh@mcc.com | Phone: (512) 338-3704 3500 West Balcones Center Dr. | UUCP: ...!cs.utexas.edu!mcc.com!cantor!tulloh Austin TX 78759 | GENIE: R.TULLOH
farren@well.sf.ca.us (Mike Farren) (05/05/90)
johno@cbmvax.commodore.com (John Orr - CATS) writes: >the Amiga's OS takes care of multitasking, so, in >general, applications have little 'say' in whether or not they get >swapped out or not Please, folks. "Swapped out" has a pretty specific general use, referring to moving hunks of memory to a hard drive when you're working with a virtual memory system - it doesn't generally mean what happens when you switch between tasks which are already memory resident. That, not surprisingly, is usually referred to as "task switching". Just call me a computer language purist :-) -- Mike Farren farren@well.sf.ca.us
al158305@mtecv2.mty.itesm.mx (Gustavo Cordova) (05/05/90)
In article <10143@sdcc6.ucsd.edu> cs163wed@sdcc10.ucsd.edu (see far) writes: > ISn't the AMiga's multi-tasking program swapping? Unless you have > several amigas at once, you can never run programs simultaneously. > Amiga's multitasking only tricks you into thinking it is running > programs "simultaneously". > After all, you get only one 68000 in an amiga, don't you? > >Chris Everhart >chrise@hubcap.clemson.edu > -- > What is the Final Outcome for China's current situation? > In China, 1992, (Lee Huan of) Taiwan will liberate Mainland! > --a prediction appearing in Usenet since Sept 1989.----- > More info available in 2 articles. You can request by E-mail So? What's one CPU got to do with it? SUN and Apollo workstations also only have one cpu and nobody questions them. The point is, if you run a program in multifinder and send it to the background to do it's transforms or whatever-Mac-geeks-do, and then enter your word processor and do some foreground work there, when you finish your WP job and re-enter the other program you'll likely find the calculations right where you left them the last time (ok, maybe an addition or a substraction more); why is this you might ask? Because ALL mac progs do.... (drum roll)... BUSY WAITING!!! Yes ladies and gentlemen, mac programs commit that capital sin in every multitalking world, so if your program doesn't have provisions to return control to the OS after a certain amount of time, you might as well run it alone; but in the amiga, each task (what a neeto name :) has an amount of time alloted to each one, besides, when doing I/O, the program simply goes to sleep until it gets what it wants, tha way, the communications program doesn't take much CPU slices, it simply tell the OS to awaken it when data is available at the port, at the same time, the WP tell the OS to wake him up when a keypress is available, and so, the spreadsheet has a bunch of CPU time available to do some number crunching... fun, isn't it? +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ | Isn't it refreshingly similar the syntax of | My other mainframe| | UNIX commands and AmigaDOS stuff? :) | is an Amiga :) | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ | Gustavo Cordova | Computer Systems majoring @ ITESM, Mexico | +=================+ Internet: al158305 @ mtecv2.mty.itesm.mx | | If at first you | al158305 @ 131.178.1.5 | | don't succeed, | BitNet: bl158305 @ tecmtyvm.bitnet | | to hell with it.| al158305%mtecv2.mty.itesm.mx@tecmtyvm | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ -- disclaimer: These are my opinions, only mine, freely distributable, for non-commercial use only.
gilgalad@dip.eecs.umich.edu (Ralph Seguin) (05/07/90)
In article <AL158305.90May5005228@mtecv2.mty.itesm.mx> al158305@mtecv2.mty.itesm.mx (Gustavo Cordova) writes: >foreground work there, when you finish your WP job and re-enter the other >program you'll likely find the calculations right where you left them >the last time (ok, maybe an addition or a substraction more); why is this >you might ask? Because ALL mac progs do.... (drum roll)... BUSY WAITING!!! Not true. I got into a discussion with somebody about this. The discussion cleared up a few things for me and for him. I found out the context switch mechanism. While it is cooperative multitasking, it is not nearly as ugly as most other cooperative systems. In multifinder, a program makes a call to GetNextEvent() (or some such similar name I can't remember). If there is no event queued, the process blocks and whatever is on the ready queue is scheduled. This is much easier to add into the OS than preemption. Admittedly, it does have a number of drawbacks. Firstly, if your program does not make any calls to GetNextEvent(), nothing else will get CPU time. Most programs that are written for multifinder now use these calls, so it is not really much of an issue. Still, preemption is better, no matter what you say 8-) Apparently Apple is beginning to see the light and they are going to encorporate it into System 8. >+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ >| Isn't it refreshingly similar the syntax of | My other mainframe| >| UNIX commands and AmigaDOS stuff? :) | is an Amiga :) | >+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ >| Gustavo Cordova | Computer Systems majoring @ ITESM, Mexico | >+=================+ Internet: al158305 @ mtecv2.mty.itesm.mx | >| If at first you | al158305 @ 131.178.1.5 | >| don't succeed, | BitNet: bl158305 @ tecmtyvm.bitnet | >| to hell with it.| al158305%mtecv2.mty.itesm.mx@tecmtyvm | >+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ >-- >disclaimer: These are my opinions, only mine, freely distributable, for > non-commercial use only. See ya, Ralph gilgalad@caen.engin.umich.edu gilgalad@dip.eecs.umich.edu gilgalad@goliath.eecs.umich.edu Ralph_Seguin@ub.cc.umich.edu gilgalad@sparky.eecs.umich.edu USER6TUN@UMICHUB.BITNET Ralph Seguin | In order to get infinitely many monkeys to type 11010 Lighthouse Dr. #234 | something that actually makes sense, you need to Belleville, MI 48111 | have infinitely many monkey editors as well. (313) 697-1048
steveg@umd5.umd.edu (Steve Green) (05/07/90)
)[ lots of stuff deleted ] ) So? What's one CPU got to do with it? SUN and Apollo workstations also )only have one cpu and nobody questions them. The point is, if you run a )program in multifinder and send it to the background to do it's transforms )or whatever-Mac-geeks-do, and then enter your word processor and do some )foreground work there, when you finish your WP job and re-enter the other )program you'll likely find the calculations right where you left them )the last time (ok, maybe an addition or a substraction more); "... you'll likely find the calculations..."??? Sounds like you are baseing your post without any firsthand knowledge.. The answer is that you are completely wrong. )why is this )you might ask? Because ALL mac progs do.... (drum roll)... BUSY WAITING!!! )Yes ladies and gentlemen, mac programs commit that capital sin in every )multitalking world, so if your program doesn't have provisions to return )control to the OS after a certain amount of time, you might as well run it )alone; )[ deleted stuff about Amiga ] Wrong again. )+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ )| Isn't it refreshingly similar the syntax of | My other mainframe| )| UNIX commands and AmigaDOS stuff? :) | is an Amiga :) | )+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ )| Gustavo Cordova | Computer Systems majoring @ ITESM, Mexico | )+=================+ Internet: al158305 @ mtecv2.mty.itesm.mx | )| If at first you | al158305 @ 131.178.1.5 | )| don't succeed, | BitNet: bl158305 @ tecmtyvm.bitnet | )| to hell with it.| al158305%mtecv2.mty.itesm.mx@tecmtyvm | )+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ Seriously though, can you please stop bashing other machines unless you have some facts. Stop makeing up things and using theory to prove a mute point. I am not saying that Multifinder is better that AmigaOS or visa-versa. In fact, I dont even like MF but from a practical point of view, there are less differences than some of you would like to admit. Here is a real world example. With MF, I was able to do a ray trace, download and word process at the same time. Yes, the ray trace and download all progressed fine. As well, I am sure that the amiga can do the same. -- What do these names have in common? Bob, Flo, Augie, Curtis, Gordon, Rick, Rhonda, Meep, Bismark, Skip, and Harry ...did I miss any?? steveg@umd5.umd.edu
aliu@aludra.usc.edu (Terminal Entry) (05/08/90)
In article <6478@umd5.umd.edu> steveg@umd5.umd.edu (Steve Green) writes: >)[ lots of stuff deleted ] >)[ deleted stuff about Amiga ] Why? >are less differences than some of you would like to admit. Here is a real >world example. With MF, I was able to do a ray trace, download and >word process at the same time. Yes, the ray trace and download all >progressed fine. As well, I am sure that the amiga can do the same. It sure can! And more! Heck dude, not only was I downloading a w/ Zmodem, Sculpt4D'ing a pic, and writing a letter on ProWrite, I had TWO other rendering programs [Turbo Silver and Videoscape) working on another pic and rendering a 200 frame animation, Modeler 3D sitting on an object, DPaint3 working on a 30 frame anim, PageStream puttering out an ad to the Laser printer, and a few shells decompressing some archives that were being batched downloaded. Alot of these applications are video intensive---oops, forgot to add, Sonix Progressive playing rock music in the background! How's that for a 4Mb 68000 based machine w/ a 40Mb HD? I'd like to see you Wacintosh do that w/ the same configuration? BTW, what were YOU using, a Mac+, SE or II??? Now if I had an A3000 w/ 16Mbs & 2Mbs chip...hmmm???? >What do these names have in common? >Bob, Flo, Augie, Curtis, Gordon, Rick, Rhonda, Meep, Bismark, Skip, and Harry > ...did I miss any?? steveg@umd5.umd.edu -The Master Multitasker Sorry guys lost control there! Just couldn't resist:-)
acliu@skat.usc.edu (Alex C. Liu) (05/08/90)
In article <9653@chaph.usc.edu> aliu@aludra.usc.edu (Terminal Entry) writes: >In article <6478@umd5.umd.edu> steveg@umd5.umd.edu (Steve Green) writes: >>)[ lots of stuff deleted ] >>)[ deleted stuff about Amiga ] >>world example. With MF, I was able to do a ray trace, download and >>word process at the same time. Yes, the ray trace and download all >>progressed fine. As well, I am sure that the amiga can do the same. >It sure can! And more! Heck dude, not only was I downloading a w/ Zmodem, >Sculpt4D'ing a pic, and writing a letter on ProWrite, I had TWO other >rendering programs [Turbo Silver and Videoscape) working on another pic >and rendering a 200 frame animation, Modeler 3D sitting on an object, Well, that sounds nice, and it is true, the Amiga multitasks, and also Multifinder IF the program is well behaved. But then again, if you are doing ALL that in Amiga, I am sure things would get pretty slow... (Ok, Multitasking is nice, but the Amiga is no cray...) BTW, do you have 2 phone lines or you also have a ReadNews program in your Amy? (Cus It is HARD t odo a Zmodem download and be posting news at the same time if you have only one phone line... Now if you had Dnet, I would believe you..) ______________________________________________________________________ Alex C. Liu | INTERNET: acliu%skat@usc.edu Voice: (213) 749-2730 | BITNET: acliu@gamera Q-Link: Alejandro | UUCP: ...!usc!acliu
FILLMORE%EMRCAN.bitnet@ugw.utcs.utoronto.ca (05/08/90)
Well, they say a picture is worth a thousand words so here is my attempt to
clarify the discussion comparing multitasking on the Amiga and Macintosh.
Note: I consider the Amiga custom chips, floating-point chips,
etc. which have special instruction sets to be co-processors,
NOT CPUs. They are not considered in the following illustration.
Also, I ignore the effects of interrupt service routines.
Legend: A = processor A, B = processor B, etc.
A,B,... are all processors of the same type (homogeneous)
< = task start
> = task end
| = task switch
SINGLE-TASKING (eg. Mac Finder, MS-DOS programs)
--------------
Task 1: <AAAAAAAAAAAAAAA>
Task 2: <AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA>
Notice that each task must run to completion before the next task starts.
COOPERATIVE MULTITASKING (eg. Mac Multifinder, MS-DOS TSRs or spoolers)
------------------------
Task 1: <AAAAAAA| |AAA| |AAAAA>|
Task 2: <AAAAAAAAAA| |AAAAAAAAAAAAAAAAAAAAAAAAAA| |AA>
Notice that the total elapsed time for a task is very unpredictable.
Also, the elapsed time for task 1 depends on how task 2 is written
(how often task 2 gives up the CPU).
Each task must be programmed with multitasking in mind (frequent calls
to system routines) in order for it to work successfully.
Mac programs which follow Apple's guidelines will multitask fairly well.
Program development costs may be higher because of extra care required.
PRE-EMPTIVE MULTITASKING (eg. Amiga, Sun, each CPU in a mainframe)
------------------------
Task 1: <AAAAA| |AAAAA| |AAAAA>|
Task 2: |AAAAA| |AAAAA| |AAAAAAAAAAAAAAAAAAAAAAAAAAAA>
Notice that each task is given an equal time slice in the CPU.
Therefore, the total elapsed time for a task is the task CPU time
multiplied by the number of tasks running (ie. it is predictable).
In general, application programs can be written as if they own
the whole machine - they do not have to keep multitasking in mind.
Of course system-type programs do have to be well-behaved.
MULTIPROCESSING or parallel processing (eg. mainframes with multiple CPUs)
---------------
Task 1: <AAAAAAAAAAAAAAA>
Task 2: <BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB>
Since there is a CPU for each task the total task time is very predictable.
Note: if there are more tasks than CPUs then some of the CPUs will start
pre-emptive multitasking.
All of these issues were covered years ago in the mainframe world.
I have simplified things a lot to clarify the comparison.
________________________
Bob Fillmore, Systems Software & Communications BITNET: FILLMORE@EMRCAN
Computer Services Centre, BIX: bfillmore
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