Nation security drove the move from analog telemetry, to digital telemetry.
Analog telemetry could not achieve 50dB SNR (about the point where the width of the INK PLOTTER ink line set the resolution) at the distances needed to monitor the (mis)behaviors of the missile systems.
By using Analog_Digital_Converters, the data_link limitations were greatly altered. If your rocket mis-behaved in mid-trajectory, you had a better chance of diagnosing the cause, because you had better reporting of the minute variations of the fluids and the vibrations and the temperatures.
I remember my first Chief Engineer staying late, several days in a row out in the lab. I went over, curious, and he explained "This is a 10-bit ADC from the Saturn Instrumentation Segment. Has a problem. Since I designed it, 10 years ago, I'm the best person to diagnose it and then ensure its properly calibrated after the NASA_spec repair_people replace the failure."
The ADC was a 10_bit current_steering successive_approximation circuit, with 10 current sources, and at least 10 discrete FlipFlops to implement the binary-search algorithm. Plus 10-bit output data holding register.
I recall a Cordwood Module FlipFlop of size 1cm by 1cm by 2cm, using capacitive input coupling to create the toggle-pulse behavior with diode steering logic and 2 transistors of 2N706. When Fairchild brought out their UL923 logic, the size was about (1/2 cm) cube, but used enough (on_chip) transistors to function down to DC without re_design.
All in 8" by 8" by 24" chassis.
By the way, in trying to develop (debug, stop explosions from broken piping) their Soviet N1 moon-launch rocket in the 1960s, with their 13 engines needing lots of large piping for oxidizer and propellant with shared turbine pumps, the Soviets kept adding more and more telemetry channels as each version rose from the pad ----- and then exploded at some distance aloft.
The final version (#5) had 13,000 telemetry channels and over a GigaBit of downlink data streaming.
After that 5th explosion, still not diagnosable (too much vibration in long piping?), the Soviets gave up their moon efforts.