RSX Radix-50 conversion utility

  Lately, I've been working on some RSX programs that do a lot of spawning of assorted tasks.

  There were some bugs involved, and I needed to check the task name arguments to the SPWN$S calls.

  These arguments are in RADIX -50 format. RADIX-50, for those of you who haven't had the pleasure of working with it is a way to squeeze three characters into two bytes. It sounds like a lot of trouble, but, it dates from the days when saving a byte here and a byte there was a big win. RADIX-50 has a limited character set - Capital letters, 0 through 9, space, $, . and %. Encoding things in RADIX-50 is why so many things in the RSX world come in multiples of threes - like filenames and extensions, and task names, for example.

  Anyway, I had reason to think some of these variables were not correct in my code. I needed to check them out - but it's hard to look at a 16 bit word and say just what three letters it represents in RADIX-50. I could have written some debug code to evaluate them, but that sounded like even more error prone work - and I didn't go into programming to look for more work to do. I also could have evaluated the words using ODT - it has a function in it that will let you see a word in RADIX-50 format. But, I really really hate ODT. I think it really stands for Odious Debugging Technique. It requires you to have up to date listing and map files handy (preferably printed out - and I hate printing things out). To be honest here, my favorite two debugging techniques for Macro-11 are the diagnostic QIO printout (if you wonder what a value is, add a print QIO to the code and display it), and the much maligned IOT trick (if you are wondering what's happening at some point in your code, put the values of interest in the registers, and then add an IOT instruction - when it gets executed, the task exits and you get to see the register values). A lot of people hate the IOT trick - it can cause problems, for instance, when  fast supervisor mode mapping gets involved. But, it's always handy and is easy to use, so I use it.

  But, like I say, RADIX-50 variables don't lend themselves to these sort of caveman's debugging techniques. So, I figured, time to write a command line utility. I like doing that - it makes me think I'm really accomplishing something.

  So, I wrote R5A. It's a utility that can translate 16 bit words into their three letter RADIX-50 format, and vice versa. It's nothing special - it uses GCML to get a command line, and a few System Library routines to translate octal to binary, binary to ascii, and RADIX-50 back and forth.

r5a.mac
  To build

>MAC R5A=R5A
>TKB R5A=R5A

To use
>RUN R5A
R5A>50712/AS
MCR
^Z

and the other way...
>RUN R5A
R5A>MCR/R5
50712

  There are two switches, that indicate what is on the command line - an R50 string, or an octal string in ascii - /R5 and /AS. /AS is the default, since that's mostly what I need to do - convert words to R50 strings. It doesn't use CSI or TPARS to evaluate the switches, like most of my utilities do (I was in a bit of a hurry, no time for niceties this go round) so the / in the switch has to immediately follow the argument.

  Natch, you can install it and invoke as a whole command line
>INS R5A/TASK=...R5A
>R5A MCR/R5
50712
R5A>