Welcome to the Humminbird Side Imaging Forums Wayne.
You need to look at the Self Test/System Status View of your 798ci unit. You can do this by looking under the Views tab in the main menu system. Scroll down until you see the “Self Test” menu and set it to “Visible”. Exit out of the menus and scroll through your available Views until you see it.
You only need to load the latest update and it will have all of the software changes that were made before it.
Depending on what software is in your unit now you may have to either insert the memory card with the software update file before the unit is turned on or afterwards. First though you need to download the software update file onto a blank MMC, SD or SDHC type memory card. You can get the software form your “My Humminbird” account on the Humminbird web site or from the downloads section of this website.
The current software version for a 798ci Si model unit is 6.300, if you have a different model name you will need a different software download.