Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!ames!cit-vax!news From: news@cit-vax.Caltech.Edu (Usenet netnews) Newsgroups: comp.sys.ibm.pc Subject: Re: Mainframe vs Micro Message-ID: <1415@cit-vax.Caltech.Edu> Date: Sat, 3-Jan-87 16:45:32 EST Article-I.D.: cit-vax.1415 Posted: Sat Jan 3 16:45:32 1987 Date-Received: Sat, 3-Jan-87 21:53:30 EST References: <657@imsvax.UUCP> Reply-To: tim@tomcat.UUCP (Tim Kay) Organization: California Institute of Technology Lines: 96 Summary: PC's have a long way to go Organization : California Institute of Technology Keywords: From: tim@tomcat.Caltech.Edu (Tim Kay) Path: tomcat!tim In article <657@imsvax.UUCP> ted@imsvax.UUCP (Ted Holden) writes: > >There are several points to consider concerning the mainframe/micro question >as it relates to databases. The 32 meg limit doesn't apply to Novell Netware. You are totally in the wrong ball park. PCs aren't going to encroach on mainfames just because the 32M limit was broken. A _typical_ drive that IBM sells (3380) has about 600 Mbytes on it. A _typical_ machine they sell will have anywhere from 10 to 500 of these drives on it. A PC can handle only two drives. One of the main concerns in designing the XA architecture at IBM was that installations were running out of address space for numbering devices (disks, tape drives, terminals, CTCAs, etc.). The old 370 architecture can handle 4,096 devices! The new XA architecture can handle significantly more. Typically, a single machine configured as above is not adequate, so IBM offers (and has offered for about a thousand years now) the ability to network these large machines. There are installations that have dozens of the machines (of the size I just mentioned) networked together. Consider that an IBM mainframe handles all of its I/O through I/O channels. These are really separate computers that have direct access to memory and run simple programs that the main CPU constructs for them. Each channel on an IBM mainframe at least as powerful as an 80386. A mainframe has many channels for each CPU. >I've seen 750 and 780 VAXs destroyed by fewer than 30 people doing database >work (or attempting same) at the same time. The PCs are faster and better. A Vax 780 is a wimpy machine that was not designed for large tasks. Clearly PCs are encroaching upon DEC mainframe type sales. Actually, it is incorrect to call DEC machines mainframes. The term they coined for them is, I believe, "supermini." The present discussion started when a claim was put forward that PCs are cutting into IBM's mainframe market. DEC offers no machine that is anywhere near the power of IBM's mainframes. IBM can _routinely_ put hundreds of terminals on a single machine, and it will perform well. Just try to network more than a few tens of PCs. >The PC revolution, like our free-market system as opposed to communism, takes >human nature into account, at least as it applies to bosses and managers. >I've never yet seen one of these who, upon hiring three new people to work >on a multi-user computer system, didn't simply add three new terminals to >the system. With PC networks, they are forced to add three new computers >to the system. And the beauty is that they do so with smiles on their faces, >since PCs have gotten to the point of being cheaper than most mainframe >terminals anyhow. This argument doesn't fly. Quite often, PCs are used as terminals for IBM (and DEC) mainframes. It requires the simple addition of an IRMA or PCOX type card, which costs about the same as an Ethernet card. The only disadvantage in using PCs is that the screens are two small. IBM sells a terminal that can have four windows on it, each of which is (I believe) 132 characters by 25 lines. Alternatively, the same terminal can be used for one huge window. I will rephrase a statement that I made earlier. Most people have absolutely no idea what the bulk of the computing power in this country is used for. They see what is being done on PCs and Vaxes, and they see lots of them. They assume that this type of computing is typical. It is not. You could probably take all the Vaxes in the world, multiple by 100, and you would not have enough computing power to replace all the IBM mainframes in the world. Every year, IBM's profits are roughly equal to DEC's SALES. None of this discussion starts to consider machines like Crays or IBM 3090s with vector processors. They can compute thousands of times faster than a PC. An 8087, for example is about 5 kiloflops. A 68881 is about 30 kiloflops. A Cray XMP 48 (by now an old machine) was about 1 gigaflop. This is a factor of 1,000,000,000 / 30,000 , = 33,000 difference in performance. In conclusion, I'd like to suggest that a PC is to a mainframe like a rubber raft is to a yacht. They both have their uses, and many people that have yachts have uses for rubber rafts. Likewise, many people that can't afford or justify yachts can afford and do enjoy rubber rafts. On the other hand, it is ludicrous to think that, because rubber rafts are becoming less expensive, the sales of yachts are falling off. Comments? Tim Caltech Timothy L. Kay tim@csvax.caltech.edu Department of Computer Science Caltech, 256-80 Pasadena, CA 91125