The DM160 is a miniature voltage indicator. The control range on the grid is 0 to -3.0 Volts.

The other side of the envelope shows the construction. When conducting the DM160 will give out light and goes dark at cut-off. In this way it can be used to indicate the logic state of the circuit it connects to.

Peter Onion says of the Elliott 803B at the National Museum of Computing: The 803 was introduced in 1960 and used six DM160's in the console. The console can be seen in a YouTube video of the 803 running its Algol 60 compiler.

Mullard describe the DM160 as: a special quality directly heated subminiature voltage indicator for use in industrial equipment such as transistorised computers.

For further information click here and for an animation click here.

The thin glass tube envelope is 5 mm in diameter and, excluding the lead out wires is 26 mm tall.

References: Datasheet & Peter Onion. Type DM160 was first introduced^¶ in 1957.

 
Absolute Maximum Operating Conditions^¶

CRT	Vh	Ah	Va	mAa
	1.0	0.03	50	0.585

Thanks to Frank Philipse for supplying the above PDF datasheet