Darrel: Yes the data is changing numbers. Four digits would need updated. Its mostly for an initial setup of a piece of equipment. A user adjusts the speed to the correct level and then starts using it.

Jerson: That answers one other question. A digit on the display is an array in code space. So the static part of the display is a large array and then each digit is a smaller array. Then lookup is used with shiftout to send the the right parts? I saw some postings about font tables but wasn't sure if they were right for this application.