A Programmer's Perspective:
Subject: Be Afraid, Be Very Afraid (NCR 399) :-)
I just happened to find your NCR399 page by mistake. Oh my God! I can't believe those are still around anywhere! I would have thought that anyone who had ever programmed one would have made it a personal goal to destroy any remaining ones. :-)
My first job out of school was for NCR. I spent the better part of three years programming that monster and installing them around Massachussetts. When I first started using it, we only had two cassette tape drives on it. To compile, you had to have one tape for your source, another for the compiler, and another for the linker, and finally one to write your object code to, It would take about 30 minutes to compile a program, and every 5 minutes or so you had to change tapes.
The programming language is Neat/AM (AM=accounting machine) The magnetic ledgers were a piece of ledger paper about 12" wide by 16" long. They had a piece of magnetec tape glued to the back which would store the information printed on the front. They were great transition systems for the small business which had always used paper ledgers to keep their books. The 399 let them keep their ledgers, but then they could feed the ledgers one at a time into the system where it would be read onto tape at the end of the month.
You would then have a statement program, or general ledger, or accounts payable which would read the tape and produce checks, or customer statements, etc.
You could also enter patches into the console after you had loaded a program. (I was known as "patches" by one of my customers for a time :-) ) Oh well, enjoy it. It was kind of like seeing an old friend, after a long time, well sort of...
Words to live by with a 399... "If all else fails hit Halt, then Reset, then Compute :-)