Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!sunybcs!bingvaxu!leah!uwmcsd1!csd4.milw.wisc.edu!neighbor From: neighbor@csd4.milw.wisc.edu.UUCP Newsgroups: comp.sys.apple Subject: Re: Expansion Box Message-ID: <3781@uwmcsd1.UUCP> Date: Thu, 3-Dec-87 22:39:44 EST Article-I.D.: uwmcsd1.3781 Posted: Thu Dec 3 22:39:44 1987 Date-Received: Sun, 6-Dec-87 20:20:38 EST References: <8712021731.aa12058@SMOKE.BRL.ARPA> Sender: daemon@uwmcsd1.UUCP Reply-To: neighbor@csd4.milw.wisc.edu.UUCP (Jeffrey Alan Ding) Organization: University of WI-Milwaukee Lines: 29 Ray, Your expansion box will cause more problems than you realize. Each line coming out of the connector has loading limits. This means that you can only hook up so many TTL gates to each line. For example. I think the Address lines can only handle 2 TTL loads each. (I don't quite remember, don't have the reference manual in front of me.) If you have cards in each of your 4 slots that you made on your expansion box, assuming only 1 load per slot per address line, you will have 4 loads on each address line. That is twice the limit. There are other lines that I think can only handle 1 TTL load. If you overload these lines your computer will malfuntion and not operate correctly. I have experience with this problem. You should also have these lines buffered. They all should be buffered. Also if the cable going from your expansion box to the computer it too long you will also develop timing problems. The only way to get around this problem is to switch every line with elctronic gates. This is probably the only way that your expansion box will work trouble free and reliably. neighbor@csd4.milw.wisc.edu