What kind of operating system is used by a Real Programmer? CP/M? God forbid --- CP/M, after all, is basically a toy operating system. Even little old ladies and grade school students can understand and use CP/M.
Unix is a lot more complicated of course --- the typical Unix hacker never can remember what the PRINT command is called this week --- but when it gets right down to it, Unix is a glorified video game. People don't do Serious Work on Unix systems: they send jokes around the world on UUCP-net and write adventure games and research papers.
No, your Real Programmer uses OS/370. A good programmer can find and understand the description of the IJK305I error he just got in his JCL manual. A great programmer can write JCL without referring to the manual at all. A truly outstanding programmer can find bugs buried in a 6 megabyte core dump without using a hex calculator. (I have actually seen this done.)
OS is a truly remarkable operating system. It's possible to destroy days of work with a single misplaced space, so alertness in the programming staff is encouraged. The best way to approach the system is through a keypunch. Some people claim there is a Time Sharing system that runs on OS/370, but after careful study I have come to the conclusion that they were mistaken.