increase the buffer of the AutoCAD text window

By Xiaodong Liang

To begin with, I’d recommend the other post on Kean’s blog

Increasing the size of AutoCAD’s command line history

you will know how to increase the size of command line history manually. At API side, there are two ways to access the Text Window buffer size, expressed in numbers of history lines: the
CmdHistLines environment variable, and the AutoCAD.AcadPreferencesDisplay.HistoryLines Automation property.

Here is how to set the environment variable from AutoLISP:

(setenv "CmdHistLines" "2048")
Here is how to set the Automation property from AutoLISP:
(vl-load-com)
(vla-put-historylines (vla-get-display (vla-get-preferences
(vlax-get-acad-object))) 2048)
Note: The value has to be between 25 and 2048.