> This is an update on my attempt to run, on the SimH 1130, > the "Lunar Landing" program featured in one of Carl Claunch's > YouTube videos. . .
Progress!! Looking at one of the sample Fortran programs in Wikipedia's article on the 1130 -- the one that finds the roots of a quadratic equation -- and in particular, looking at the data cards that follow the program, adjacent triplets of numbers all strictly formatted as sign, three digits, decimal, three digits , i.e. FORMAT 3F8.3 , led me to wonder if the initial console input for the "Lunar Landing" program might have equally strict formatting requirements. I was wrong earlier about the human-readable main program only handing console I/O -- it does in fact output the initial console message, but it also does the output to the lineprinter (and the logical unit for those WRITES is held in a variable "IOUT" that's also being passed to ORBIT, which suggests I might want to revisit using the DMS configured for 1403 printer, by changing the DATA statement in the main program that initializes "IOUT"). And it is ORBIT subroutine that's prompting on the console for "ANGLE" and "VELOCITY" (ORBIT gets a logical unit number for the READs passed as argument "IN"). I can't examine the FORMAT statements in ORBIT for reading ANGLE and VELOCITY, since I don't have source code for that piece of the program, but a big clue is that the field widths for the values of "INCREMENTAL VELOCITY" and "INJECTION ANGLE" that come out on the lineprinter show up as 11 characters wide on the lineprinter output (even when the values are junk), and there are F11.0 and F11.3 formats in the code. So instead of entering, for example, "10" and "10000" on the console, I tried entering "0000000010." and "0000010000." And that worked! At any rate, I now see "INCREMENTAL VELOCITY" and "INJECTION ANGLE" being reflected on the lineprinter output as the same numbers as I entered on the console, and I'm actually getting something that looks like a trajectory plot. It isn't exactly heading the right way, but actually learning to play the game will come later. ;->
