IIRC, the Electra Bearcat 210 didn't exist until 1977.
My first scanner was a Heathkit GR-1132 8 channel crystal base/mobile scanner that I built myself back in 1977. I received the GR-1132 as a Christmas gift. I couldn't afford a Bearcat 210 back in those days.
I remember the SBE Opti-Scan base/mobile scanner. You inserted a punched card that had all your channels programmed. The scanner optically scanned the card and the BCD binary data directly programmed a PLL synthesizer to tune the receiver. For each channel you punched holes representing the 4-bit binary coded decimal (BCD) digit for each digit of the frequency. So it was one line of BCD data for each channel and the card had enough dots that could be punched to hold 8 or 16 channels. I never owned one of these but have seen them. One mistake and the card is trashed and you need to start over with a new card. IIRC, the scanner came with a bunch of blank cards ready to be punched.
The technology leap made by the Bearcat 210 was that a microprocessor controlled the PLL synthesizer and provided a LED display and a keypad for entering frequencies. Channel information was stored in the microprocessor's memory instead of on a punched card. Scanners like the SBE Opti-Scan was an intermediate step from individual crystals to PLL synthesized and microprocessor controlled programming.