Calvin is a screen text editor written for the IBM PC. It implements a subset of the Unix screen editor vi(1).

This editor requires MS-DOS 2 or higher and 128K of memory. It will use all available memory for storing the file, etc.; optionally, it can store additional information on disk.

It supports EGA 43-line and VGA 50-line modes.

Important limitations:

• No regular expressions (searches only for literal strings)
• No support for tags. (Workaround: Use "sed" as filter.)

If you experience screen corruption using calvin in VirtualBox, it is due to VirtualBox BIOS bugs. To work around this problem, set the following environment variable:

SET EXINIT=set vidcompat 2

This configures calvin to avoid the buggy CGA BIOS calls.