Path: utzoo!mnetor!uunet!husc6!sri-unix!sri-spam!rutgers!iuvax!pur-ee!pc.ecn.purdue.edu!ga.ecn.purdue.edu!edward From: edward@ga.ecn.purdue.edu (Edward L Haletky) Newsgroups: comp.sys.ibm.pc Subject: Help On multitasking Message-ID: <314@ga.ecn.purdue.edu> Date: 17 Dec 87 14:37:59 GMT Reply-To: edward@ga.ecn.purdue.edu (Edward L Haletky) Organization: Purdue University Engineering Computer Network Lines: 24 Keywords: MSDOS, Multitasking, cshell Netlanders, I am trying to write a multitasking shell for am IBM PC, either as a replacement for the braindead command.com or as a cooperating system. I would like it as close to csh as much as possible. The processes will have to be preemptive. This implies that in order to put a job in the background I need to make an estimate of how much memory is needed (data, program, etc). How would I go about finding this out? I would like to continue adding background jobs until memory is gone. The system would be prioritized. I assume I am approaching this correctly. In order to switch processes I believe I would need to keep a record of all the registers and necessary interupts as well as the current memory location of the executing code. The main problem I can think of is in keeping track of what memory is available for each process to call. Any help would be appreciated. (either '286, '386, or 8088 cpu`s). Thanks in advance: ===================================== ^ ================================= Edward L. Haletky |E |o| U| "To race against the sky..." Usenet: ~!pur-ee!edward |L ^/| |\^ S| "The world of the Arpa: edward@ga.ecn.purdue.edu |H / | | \ A| immagination is boundless." =====================================/__-|-__\=================================