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19

The use of such letters was common in mathematics long before programming existed. x, y, z were used as variables by Descartes in 1637; in his framework, a, b, c and other letters towards the start of the alphabet represented known values, letters towards the end of the alphabet represented unknown values. The use of i, j etc. doesn’t go quite that far back, ...


8

One possibility to look at might be the Hercules emulator, which emulates the IBM S/370, ESA/390, and z/Arch systems. This is emulating the 'bare iron', and does not include the operating system or utilities, but there are sources for OS images and compilers listed on that page.


6

The compilers I produced or helped produce (40-50 years ago) produced code that kept all floating point numbers as simple 2's complement mantissa/exponent form. It converted them to hardware FP representation and invoked the FP unit to process the arithmetic, then on return converted them back. You have to remember, back in those days FP hardware had a very ...


6

These aren't mainframes by any manner of means, but I've successfully compiled and run Fortran programs on an emulated: DEC PDP-11 running RSX11 DEC PDP-8 running OS 8. Both of these ran under SimH on a Raspberry Pi Zero. The PDP-8, being a small machine, typically ran from paper tape rather than cards. I have reason to believe that another early ...


5

Does it have to be a mainframe, or PDP-11 or VAX would be good enough? If the latter, then there is SIMH, and there is Bitsavers' Software Archive. There was a FORTRAN compiler on BSD UNIX for sure. Better yet, there is no need to simulate the whole system. For convenience, one can use a user space PDP-11 emulator. Binaries can be taken from here, 2.11 BSD ...


4

There are emulators for the historically significant systems produced by Control Data Corp. cdc and Cray cray. DtCYBER, which can be run on Windows and Linux and is available as source code under GPL 3.0 terms. DtCYBER does not include operating systems, compilers, etc., which the user must provide for themselves--a tall order, but probably not impossible. ...


3

Do you consider the PDP-10 a mainframe? Here is a TOPS-10 distribution with Fortran included: http://www.steubentech.com/~talon/pdp10/


3

FORTRAN carriage-control from record-based IO on legacy systems can be quite challenging on modern octet-stream systems. If SIMH is using CRs and BSs to format output, the traditional way of cleaning up the stream is to use col -b as a filter to merge the control characters. Update: Okay, so this is a question about HTML overprinting, for which there seems ...


2

Experimenting with CSS along the lines (pun intended) of "line-height:0" yielded this satisfactory result .over { line-height: 0; margin-top: 0.5em; margin-bottom: -0.5em; } <pre>FIRST LINE PREVIOUS LINE <div class="over">GOOD BYE XXXX XXX HELLO WORLD</div> NEXT LINE LAST LINE</pre> Things are slightly trickier: the default line ...


1

Beside the already mentiond Hercules emulation, why not using a real mainframe? The Gesellschaft für historische Rechenanlagen (Society for Historic Computing Machinery) in Munich does offer a free remote login to a (rather modern, 1988) Cray Y-MP. The Y-MP runs usually 24/7. On selected days, a CDC Cyber 960, the last iteration of the CDC6600 design, can ...


1

The obvious reason why "Hello World" isn't printed is that if (i=j) print 10 is not standard Fortran in any dialect I have ever seen in 40+ years of Fortran programming. Even in Fortran 90 and later, the relational operator for equality is == not =. If there is a "bug", probably it is the fact that the compiler didn't print an error message, or your ...


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