Talk:Mainframe computer
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Some PDP's were mainframes.
Year 18-bitters 12-bitters 16-bitters 36-bitters 1960 PDP-1 ------------------------------------------------------------ 1961 | \ 1962 PDP-4 <--- LINC -------- \ 1963 | PDP-5 \ \ | 1964 PDP-7 | \ \ PDP-6 1965 | PDP-8 --\ | \ | 1966 | PDP-8/S LINC-8 | | 1967 | | | | PDP-10 KA10 1968 PDP-9 PDP-8/I,L | | | 1969 | | PDP-12 | | 1970 PDP-15 | PDP-14 PDP-11(/20) | 1971 | PDP-8/E / | \ | 1972 PDP-15/76 PDP-8/M PDP-11/05 | PDP-11/45 -- PDP-10 KI10 1973 | / | PDP-11/40 | \ | 1974 | / | | | \ | 1975 PDP-8/A PDP-11/03 PDP-11/04 | | PDP-11/70 PDP-10 KL10 1976 | PDP-11/34 | PDP-11/55 | | 1977 VT78 | PDP-11/60 | | 1978 PDP-11/34C VAX-11/780 PDP-10 KS10
In a nutshell all the 36-bitters were mainframes and the rest weren't.
DEC pulled out of the mainframe business before completing the PDP-10 KC10 and jilted their whole mainframe customer base (including CompuServe and MCI/Tymenet) which marks the beginning of the end for DEC since many of those customers moved to UNIX not VMS where DEC couldn't pull the rug out from under them again.
Removed this:
- The internal redundancy of these computers can be such that, in at least one reported case, technicians could move one from one site to another by disassembling it piece by piece, and reassembling it at the new site, whilst leaving the machines running. The switchover in this example took place entirely transparently.
I know this is in the Jargon File, but on reflection a better and more specific source would be nice. --Robert Merkel 05:11, 17 Feb 2004 (UTC)
mainframes used non-"dumb" terminals, with some editing and form functionality in the terminal itself. in "dumb terminals" each keypress was transmitted to the host, which updated the display accordingly. the "dumb terminal" was coined in contrast to the terminals used before with mainframes that had more smarts.
comparison with supercomputers: basic idea: supercomputers are for compute tasks, mainframes are for reliability and io problems. actually the difference is pretty hard-and-fast one in my opinion. if you look at products marketed by suprecomputer companies and mainframe companies, you see at least the following differences: supercomputers are geared towards doing computations instead of organising data and shuffling around io. mainframes are engineered for reliability, availability and serviceablity. mainframes typically have relatively feeble cpu power compared to their contemporary high performance computing platforms. mainframes are designed to reliable transaction processing, whereas supercomputers are designed to churn through computative workloads with i/o systems fast enough not to bog down the computation business.
there is a saying: a supercomputer is a machine that converts an i/o bound problem to a compute bound problem.
sorry i'm not much good with producing wikipedia-quality article text..
Where does the breakdown of programming languages used come from? I know that a lot of mainframe programming was done in Assembler, and much of that code is still out there being maintained. After Assembler, COBOL was popular, and probably is the most popular high-level language out in mainframe-land; but is it 90% of development? I doubt it. Nowadays, there is a lot of development in Java (especially on Websphere [which as far as I can tell is an IBM mainframe version of Apache], but also in CICS). C/C++ has been used for years (I know because I've done some). Then there are all the scripting languages: REXX, EXEC, CLIST, even JCL.