Xref: utzoo comp.unix.xenix:2199 comp.unix.microport:607 comp.periphs:929 Path: utzoo!mnetor!uunet!husc6!mailrus!nrl-cmf!ames!lll-tis!oodis01!uplherc!sp7040!obie!wes From: wes@obie.UUCP (Barnacle Wes) Newsgroups: comp.unix.xenix,comp.unix.microport,comp.periphs Subject: Re: Thoughts needed Message-ID: <224@obie.UUCP> Date: 6 May 88 06:07:27 GMT References: <4144@orstcs.CS.ORST.EDU> Organization: Great Salt Lake Yacht Club, north branch Lines: 41 Keywords: Compaq xenix microport multi-user multiport Summary: Real-time DAQ on Unix? Get real! In article <4144@orstcs.CS.ORST.EDU>, kean@mist.cs.orst.edu (Kean Stump) writes: > > I need recommendations for a multi-user multi-tasking os that will run > on the following equipment: > > I have a Compaq 386/20 with 5 meg ram [ all sorts of goodies deleted ] > > I'm also considering Concurrent-Dos and PC-MOS/386 as runners-up. > One of the major requirements is that real-time sampling on the order > of 10K samples/sec (~40 bytes/sample) needs to be possible (the Compaq > will spend some time on a chunk of ice in the Arctic next spring > collecting data from a variety of instruments dropped through a hole in > the ice) and a good C and FORTRAN (8-<) compiler are needed. Hmmm... Have you carefully though this out? A Unix (or unix-like) system is probably not your best bet for doing data acquisition on. Unix was designed from the beginning to be a time-share system, not a real-time system. If you really need to acquire data at this rate, you will be better off sticking with good ol' boneheaded MS-DOS, where you won't have to worry about another user, or something in the crontab, blowing your data acquisition away. There are several good compilers available. High-C 386 is a screamer, and supports the 387. MicroWay sells C and Fortran compilers that generate 386 code, and support either the 387 or the Weitek. Have you thought about where you are going to store 400K/sec of data? Most hard disks will not run at that rate consistently, and definitely not if any head seeking is going on. I don't know if cartridge tape drives are fast enough, either. You may end up looking for a FAST 9-track system just to be able to store the data! That is what I've settled on at work, but some of our daq requirements are even tighter than yours. -- /\ - "Against Stupidity, - {backbones}! /\/\ . /\ - The Gods Themselves - utah-cs!uplherc! / \/ \/\/ \ - Contend in Vain." - sp7040!obie! / U i n T e c h \ - Schiller - wes