VERY weird . . . .in the choice of part number assignment of that I.C. . . . . .UNLESS . . .that was being from the units first line of marking.
In my eyes mind, I would want to see that being as "shorthand" for a "HC14" . . . . . which is a schmitt trigger enhanced hex inverter.. . . . as being a CMOS product
THAT of which is being a high speed CMOS . . . . versus . . . . .being its companion common transistor-transistor-logic product.
BUT the D2905A schematic is showing the ACTUAL use of a quad op amp LM324
Here . . . . . one can plainly see that LM324's were used on DT2905 multimeter boards.
So . . . . . iroshanjaya . . . . .what say you ?