I don't remember exactly when I bought my first PC computer, but it should be around 1984 or 1985; it was a "PC clone" Printaform computer that featured MS-DOS 2.11 with Batch files executed by command.com program. I vividly remember that the Batch features of that time were enough to write many interesting programs. It had variable management via SET
command and %variable%
value replacement, and FOR
, IF
and CALL
commands, including recursive subroutines.
Shortly after that I read an article in Dr. Dobb's Journal that show me how to modify command.com's environment variables from a running program, so I wrote my first program of this type, LET.COM, that allowed me to perform advanced variable management in Batch files, like arithmetic operations, data input, etc. many years before the modern cmd.exe Batch file features.
You may review the history of MS-DOS development, including Batch file features, in many sites in the web, like this one in Wikipedia.