Does anyone have any info about 1970s-era National Semiconductor LED modules?

Hi, All, The Google has failed to illuminate me. I have a handful of what look like 1970s 8-digit calculator modules with National Semiconductor logos and 1975/1976 manufacturing dates. Both types of modules have the 8-bubble plastic digit magnifiers common for LED calculators of the era, but one has 6 digits-worth of diodes behind the plastic, and the other 8 digits. Both have the same external profile and number of off-board solder pads, but different numbers of pads going to places under the epoxy blob that protects the IC. One of the modules just has "650" in copper at the edge of the board, the other has M830 stamped in the same sort of ink/paint that has the NS logo and the mfg date. I know National Semi made lots of LED modules back in the day. I have a few simple digits and was able to find docs on them without much of a search. These are a puzzle. The ones with 8 digits installed are very possibly calculator modules. I've never seen this sort of display with only 6 digits out of 8 populated. I have no idea what they are, but one tangental Google hit suggests they could be DVM modules, but I supposed they could be clock modules or counter modules. If anyone would have a mid-1970s or perhaps early 1980s National Semiconductor databook that covers LED displays, that might have some info. I do not (I only have NS memory/logic books). Thanks for any hints or tips, -ethan