Here is is (hopefully it pastes here properly):
${execpi 60 DJS=date +%_d; cal | sed s/”(^|[^0-9])$DJS”‘\b’/’\1${color yellow}'”$DJS”‘$color’/ | sed ‘s/^/${alignc}/’}

I tried the program, but I’m getting empty .bin files.
The “write_ar” functions are returning a 69 00 response instead of the expected 90 00.

Any ideas?

I realize that I didn’t cover this in the post, but the calendar display relies on using a fixed-width font to align the text properly because conky only offers simple alignment tools. In your case, it looks like the font you’re using has spaces that are more narrow than the numbers, so things don’t line up properly. I use the line xftfont Bitstream Vera Sans Mono:size=8 to change my entire conky setup to use a fixed-width font, but the comment above by Ernesto shows an example of setting the font for only the calendar.

Thanks for the tip! I’m glad that the code was useful!