Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!apple!sun-barr!newstop!sun!stpeter!cmcmanis From: cmcmanis@stpeter.Sun.COM (Chuck McManis) Newsgroups: comp.sys.amiga.tech Subject: Re: 2 Ext. Floppies on A500? Message-ID: <130373@sun.Eng.Sun.COM> Date: 17 Jan 90 18:27:39 GMT References: <1038@lpami.wimsey.bc.ca> <618@xdos.UUCP> Sender: news@sun.Eng.Sun.COM Reply-To: cmcmanis@sun.UUCP (Chuck McManis) Distribution: na Organization: Sun Microsystems, Mountain View Lines: 61 In article (Dan Vander Ploeg) writes: >An excellent model of civilized discourse! On the other hand, Chuck >McManis, whose postings I used to read no matter what the subject >line, seemed almost as rude as Larry Phillips. What is it about the >Net that encourages such behavior? I apologize for my rudeness, it is always inexcusable. In the course of watching this group grow from it's merest beginnings of net.micro.amiga to the current traffic killer I've become a bit jaded I suppose. It would appear that Larry and I both read your message to be : "I keep asking people if I can run more than 1 external drive, and both they and the documentation tell me I can't. So no one has answered my question, 'Can I run more than 1 external drive?'" It reads sort of like a non-sequitur. Doug's response was indeed the correct one. Specifically : Yes, you might be able to do it, however there are several random factors such as the amount of excess power available from your power supply. If the power supply meets C/A specs then you will probably be fine however many power supplies derate things such as load regulation when they get near the upper limits of the spec. A good power supply will be in spec right up to the limit, but those are expensive and C/A doesn't care to spend a lot on the power budget. Thus it might work most of the time until both floppies try to step at the same time whereupon your system will crash. If you have a scope and a pile of power resistors you can characterize your supply by drawing more and more current from it while measuring line regulation, ripple, and transient response (ie what happens when you change the load quickly). Then you can make a quite qualified statement about whether or not the configuration will work. Be sure and check the supply cold (use freeze spray) and warm (a hair dryer works fine). Given that effort you will know that your supply works or doesn't, but C/A may have (I believe they do) several suppliers for power supplies, and there are variations within the same power supply manufacturer's units. So if you find that your system will handle it, you can't generalize that to another system. Because of all these factors a couple of things come out : 1) Asking for other people's experience is less useful than it might originally appear. 2) Your answer won't necessarily be valuable to anyone else. If you had asked the question, "What is the worse that could happen if I tried this to see if it will work?" Then the answer is a simple, the system won't boot in the worse case, and will crash more frequently in the common case, and will run fine in the exceptional case. What I personally wanted to avoid was accidently letting someone who was on an extremely tight budget mistakenly believe that this had a good chance of working and to go out and spend $X on one or two drives only to find that their power supply couldn't hack it and then blame "us" for the bogus advice. That combined with some built in aversion to newcomers to the Amiga that buy one and then bitch about what it doesn't do as opposed to what it does made for an ugly situation. I'm sorry. P.S. Some external drives don't pass power, others do. Make sure you get one that does. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@Eng.Sun.COM These opinions are my own and no one elses, but you knew that didn't you. "If it didn't have bones in it, it wouldn't be crunchy now would it?!"