IBM's Time Sharing Option for MVS, adding interactive data processing to a system built for batch processing of data. In the beginning, TSO was mostly used with IBM 3270 terminals - beasts with a keyboard the size of a C64, no graphics or national characters and operated in block mode, i.e. all data on the screen would be transferred at the same time instead of character by character.

The IBM 320 terminal running under TSO would not support scrolling - as the 3270 was/is a screen-oriented terminal, as opposed to character-based terminals like the DEC vt100. If your screen was full, three asterisks (***) would appear at the bottom of the page - pressing the Enter key another time would clear the screen and continue your output. Fancy terminal IO was possible - a special access method for terminals called TCAM even allowed full screen processing, provided you knew your Assembler.

TSO knew a feature like today's shell scripts or batch files, called .CLIST.

Later on, IBM added SPF, still later ISPF to TSO, adding a somewhat more menu- and mask-oriented user interface.

Log in or registerto write something here or to contact authors.