Re: Is it possilble to use timer interrupt in Apple II?

["Michael J. Mahon" <mjmahon@aol.com>]

bluebird wrote:
> That's very bad news.
>
> Then we can't make any operating system in Apple II environment.

Well, a _multiprogramming_ OS is problematic, but the Apple II
supports a number of capable operating systems (some even support
a _form_ of multiprogramming!).

> Is there any workaround for multi-threading without any expansion slot
> card?

Everthing depends on what programs the system must support.

A relatively small number of Apple II programs use only resources
that can be effectively virtualized by an operating system.  Most
freely access the hardware control addresses and most if not all
of the memory map.  Few are candidates for sharing one Apple.

Of course, since you mention multithreading, perhaps you are
planning to write your own multithreaded program, and are looking
at a kernel to support it, in which case no conflicts will arise
in a correct program.  ;-)

Take a look at Contiki.  It's an example of a solution:
http://www.sics.se/contiki/about-contiki.html

-michael

NadaNet and AppleCrate II: parallel computing for Apple II computers!
Home page: http://home.comcast.net/~mjmahon

"The wastebasket is our most important design
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