Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!whuxl!whuxlm!akgua!gatech!seismo!hao!nbires!oasys!maa From: maa@oasys.UUCP Newsgroups: net.arch Subject: Re: Addressing modes Message-ID: <175@oasys.UUCP> Date: Fri, 14-Feb-86 18:56:13 EST Article-I.D.: oasys.175 Posted: Fri Feb 14 18:56:13 1986 Date-Received: Mon, 17-Feb-86 05:28:51 EST References: <946@garfield.UUCP> <3421@nsc.UUCP> <1404@gitpyr.UUCP> Organization: NBI,Inc, Boulder CO Lines: 30 > I like double and triple indirection. They probably don't justify > themselves in terms of speed, though. But I still like them. > I like indexed addressing (INDEX+constant)...and an instruction that > sums two values and gets the address pointed to by the sum would be cute > for array manipulation. But then, I'm just an assembly hacker. > > There was a computer in the basement of the University of Colorado EE building that I spent quite a lot of time playing with. It's name was GPL-3055, built by the Librascope division of General Precision. [There were only three of these ever built--for the DoD of course :-)] This computer supported infinate inderection with indexing at every level. I.e. all address had an indirect bit and index register number in them. A guy I knew was trying to write some program that made use of indexing after several levels of indirection. I don't think he ever got it to work, though. The word size on this beast was 8*6 bits and most the instructions had a field in them to control which characters in the word were operated on. It also had nice colourful instruction names like BRING, KEEP and JERK. I think it's a shame that all these wondedful old computers with strange architectures are being retired. [I saw pieces of GPL-3055 in the local electronics junk store a year or so ago.] I think that the current EE/CS students are missing a lot by not getting to play with them. Happy hacking, Mark