Page "IBM 3270" Paragraph 8

In this way, the CPU is not interrupted at every keystroke, a scheme that allowed an early 3033 mainframe with only 16 MB to support up to 17, 500 3270 terminals under CICS.

On the other hand, vi-like behaviour was not possible.

( But end-user responsiveness was arguably more predictable with 3270, something users appreciated.

) For the same reason, a porting of Lotus 1-2-3 to mainframes with 3279 screens did not meet success because its programmers were not able to properly adapt the spreadsheet's user interface to a " screen at a time " rather than " character at a time " device.