gow@sakari.mrceg (Ed Gow) (07/25/90)
I am considering buying an Amiga and I hope that some of you kind people will advise me about some down-and-dirty technical matters. 1) How does the AmigaDOS scheduler work (specifically, what stops one task to allow another to execute)? 2) Is the Zorro bus a good bus? Is the spec openly available for developing add-on hardware? 3) What books are best to learn more about this kind of stuff and to understand the system calls? I'm not easy to e-mail to because in things such as this GE is in the dark ages. (They have, however, started working on frescos on the ceilings so we're hoping for a renaissance.) Even brief postings of this info would be much appreciated. -- ------ Ed Gow ------ uwm!mrsvr!gemed!sakari!gow ----------- My opinions are NOT those of GE. Three cheers and a tiger for me!
cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) (07/26/90)
In article <GOW.90Jul25102024@sakari.mrceg> gow@sakari.mrceg (Ed Gow) writes: >1) How does the AmigaDOS scheduler work (specifically, what stops one >task to allow another to execute)? There is a clock interrupt like there is on most (all?) multitasking OSs that periodically interrupts the CPU and starts a new task if the current task's quantum has expired and there is another task ready to run. Other ways in which tasks change are system calls that can affect task state such as Signals being set can cause a task switch. From the perspective of a programmer this is all invisible, you just write your code the system will take care of the multitasking. The caveat is that you write your code assuming that there will be other tasks running and be nice about asking for things like more memory, devices, etc. >2) Is the Zorro bus a good bus? Is the spec openly available for >developing add-on hardware? It is as good a bus as your likely to find. It is a bit processor family specific (68K) but that isn't a necessarily a bad thing. >3) What books are best to learn more about this kind of stuff and to >understand the system calls? Well, there isn't a good technical introduction to the Amiga per se, however reading Volume 3 of the ROM Kernel Manual "Libraries and Devices" especially the part on the exec.library will give you a good feel for how the pieces work. Rob Peck's "Programmers Guide to the Amiga" has a pretty good overview of how those pieces work together. >I'm not easy to e-mail to because in things such as this GE is in the >dark ages. (They have, however, started working on frescos on the >ceilings so we're hoping for a renaissance.) Even brief postings of >this info would be much appreciated. And you can post to Usenet so things will never be the same again ... -- --Chuck McManis Sun Microsystems uucp: {anywhere}!sun!cmcmanis BIX: <none> Internet: cmcmanis@Eng.Sun.COM These opinions are my own and no one elses, but you knew that didn't you. "I tell you this parrot is bleeding deceased!"
n8643084@unicorn.WWU.EDU (owings matthew) (07/26/90)
In article <GOW.90Jul25102024@sakari.mrceg> gow@sakari.mrceg (Ed Gow) writes: >I am considering buying an Amiga and I hope that some of you kind >people will advise me about some down-and-dirty technical matters. > >1) How does the AmigaDOS scheduler work (specifically, what stops one >task to allow another to execute)? I am not sure about it but I believe it works like this: The amiga's kernel, Exec, keeps a circular queue of currently running tasks along with their prioritites, and then gives each a certain amount of time based on its priority. Execution is not determined by the program itself; it is all done with the o.s. I am sure someone else can provide more detail (and correct my mistakes?) >2) Is the Zorro bus a good bus? Is the spec openly available for >developing add-on hardware? Sorry, I don't know anything about this. >3) What books are best to learn more about this kind of stuff and to >understand the system calls? If you just want to learn more about it but not in the context of a particular language I would suggest looking up old articles about the amiga. Byte had some detailed articles on the amiga's operation when it was new. If you want to know about the system calls then check out the manuals from Addison Wesley: amiga Rom Kernel reference manual: libraries and devices, Includes and AutoDocs, and Hardware reference manual. They should be at Software etc. or Walden books. >------ Ed Gow ------ uwm!mrsvr!gemed!sakari!gow -----------
gow@sakari.mrceg (Ed Gow) (07/26/90)
Thanks to those who responded to inform me. I had heard some ill-founded rumors about "no TRUE multitasking on Amiga" that had me concerned. Book reviews are still welcome (by me anyway, I suppose that long-time readers of this group have seen it all before). If you can E-mail to me then so much the better, but mail may bounce. Again, thank you. -- ------ Ed Gow ------ uwm!mrsvr!gemed!sakari!gow ----------- My opinions are NOT those of GE. Three cheers and a tiger for me!
UH2@psuvm.psu.edu (Lee Sailer) (07/27/90)
Trust McManis. the two most useful books are
1. Programmer's Guide to the Amiga, by Rob Peck, Sybex.
2. Amiga ROM KERNEL Ref. Manual: Libraries and Devices, Addison-
Wesley, 1990.
A beginner needs 1. A programmer can probably start with 2.