Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!motcid!king From: king@motcid.UUCP (Steven King) Newsgroups: comp.sys.amiga Subject: Re: Amigavision, and Multitasking Message-ID: <3512@grape3.UUCP> Date: 13 Jun 90 20:53:50 GMT References: <25935@netnews.upenn.edu> Distribution: na Organization: Motorola Inc., Cellular Infrastructure Div., Arlington Heights, IL Lines: 35 charles@eniac.seas.upenn.edu (Chuck the GREAT) writes: >Hello, I have two areas of intrest for the experts on the net. >(1) How does the Amiga truely multitask. Does it have more than one processor or does there have to be more than one processor in order to multitask? I > heard one person say that there was no true multitasking because there was only on processor. The person you heard is confusing multiTASKING with multiPROCESSING. Multitasking is the ability to run multiple programs "simultaneously" on a single processor, while multiprocessing is actually having more than one processor. I put "simultaneously" in quotes because a processor can only do one thing at a time in the real world. However, if you swap tasks rapidly enough (run a few instructions from task A, then a few from B, then a few from A again) it looks to the user like both tasks are running at exactly the same time. This is what the Amiga does. Mind you, if you play tricks you can get almost any computer to do this. People wrote programs that grabbed the 60Hz interrupt on the Commodore 64 and used it to play music continuously in the background, regardless of what other program the user was running. This is a limited form of multitasking. I wouldn't call the C64 a "multitasking computer", though. To meet that definition in my eyes, a computer's operating system must be able to cleanly swap between generic programs with no special hacks on the programmer's part. The Amiga does this quite handily. The Amiga also uses a limited amount of multiprocessing. It has co-processors that handle the grunt work of video and audio output. This is to true multiprocessing what the music program on the C64 is to multitasking. I don't consider the Amiga a true multiprocessor computer. -- ---------------------------------------------------+--------------------------- Let others praise the ancient times, I'm glad I | Steve King (708) 991-8056 was born in these. | ...uunet!motcid!king (Ovid, c. 53 BC) | ...ddsw1!palnet!stevek