From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,ce6f6f23c4e880ad X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-06-24 22:17:06 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed1.cidera.com!Cidera!cyclone.columbus.rr.com!cyclone3.kc.rr.com!news3.kc.rr.com!twister.socal.rr.com.POSTED!not-for-mail Message-ID: <3D17FCEE.B24B69D8@san.rr.com> From: Darren New X-Mailer: Mozilla 4.77 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Multitasking theory question References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Tue, 25 Jun 2002 05:17:05 GMT NNTP-Posting-Host: 66.75.151.160 X-Complaints-To: abuse@rr.com X-Trace: twister.socal.rr.com 1024982225 66.75.151.160 (Mon, 24 Jun 2002 22:17:05 PDT) NNTP-Posting-Date: Mon, 24 Jun 2002 22:17:05 PDT Organization: RoadRunner - West Xref: archiver1.google.com comp.lang.ada:26690 Date: 2002-06-25T05:17:05+00:00 List-Id: tmoran@acm.org wrote: > As to DOS, IIRC there were system calls explicitly to allow you to > run while a system call was blocking its caller. No. There was a system call to tell you whether the interrupt routine had been entered while DOS was already active. If you called DOS again while this was set, you scragged the stack frame and crashed the machine. DOS switched to its own stack area when you called it, and switched back when you returned, and this prevented *anything* from being reentrant in DOS. -- Darren New San Diego, CA, USA (PST). Cryptokeys on demand. ** http://home.san.rr.com/dnew/DNResume.html ** ** http://images.fbrtech.com/dnew/ ** My brain needs a "back" button so I can remember where I left my coffee mug.