This exhibit carries the IBM equipment makers branding although it was made by Philips, this a purpose designed long life double triode for computer use where hum, microphony and noise are not important.
The 5965 is a special quality double triode designed for use in computer circuits. The 5965 will maintain its emission characteristics after long periods where the valve is biased to cut-off. This characteristic equates to use in a bi-stable or flip-flop circuit. The 5965 is not designed for audio use.
The heater is centre tapped for use at 6.3 or 12.6 Volts but in a parallel connection.
It is also labelled as a E180CC showing that the two Types are equivalent.
The anode face view. Note that the anode is large for the current rating.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 59 mm tall.
References: Datasheet. Type 5965 was first introduced in 1954.