On a seven segment display the hexadecimal characters can be displayed thusly:
_ _ _ _ _ _ _ _ _ _ _
| | | _| _| |_| |_ |_ | |_| |_| |_| |_ _ _| |_ |_
|_| | |_ _| | _| |_| | |_| _| | | |_| |_ |_| |_ |
Simple enough, eh?
I once ran across a microcomputer training manual, (If memory serves, it was distributed by Ampex.) that claimed the correct way to display the hexadecimal characters was as follows:
_ _ _ _ _ _ _ _ _
| | | _| _| |_| |_ |_ | |_| |_| |_ _ _| |_ |_| |
|_| | |_ _| | _| |_| | |_| | | |_| |_ |_| | | | |_|
The explanation was that this eliminated the possibility of confusion when viewing an inverted display. I dismissed this as unique and amusing lore, until I encountered a customized Control Data Corporation, FDS disk drive. I needed to change a parameter on the drive and watched with amusement as I pushed the increment button and the display skipped `9' and `E' and didn't `roll over' until it incremented past `J'! Now, given that this was a 200lb. disk drive mounted in a rack, (with very specific instructions on the need for the unit to remain level during operation), I am at a loss to explain the need for this type of display. I have never seen such a display since, nor sadly, have I been able to track down that training manual again.