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@@ -6,3 +6,6 @@ This repository includes a bootable PO tape and a sigma.ini file that can be use
 The PO tape and cpcpdoc.txt files were provided by Keith G. Calkins from his archive of CP-V material at https://www.andrews.edu/~calkins/sigma/.
 
 The cpcpdoc.txt file is a description of booting CP-V using siggy, a dos based simulator written by Keith and George Plume in th 90's.  This may help someone new to CP-V to get started.
+
+Note:
+The CP-V operator interface was activated by the INTERRUPT button  on the sigma front panel.  The Interrupt button is simulated in simh by entering the code 0x10 in the consle window.  On a Mac I installed the Unicode Hex Input keyboard and typed ALT-0010 to enter the 0x10 character.