DEC H-222A Ferrite Core Memory The H-222A ferrite core memory unit with capacity of 16K x 18 bits is originally from PDP-11 computer made by DEC. The size of the memory unit is 397 x 220 x 15 mm and consists from two boards. The first board (on top) is controll unit with Unibus interface. The second board (bottom) contains the ferrite plane memory.

A photo of solder side of the top board (controll unit).

The top view of the bottom board. The ferrite plane is protected with a plane board.

A solder side of the ferrite core plane. It is bottom side of the memory unit.

The ferrite core plane. It is splitted into 36 blocks. Each block has 32 columns.

A detail view to block's corner of the ferrite core plane. The wire has 0.08 mm diammeter and the black knots are repairs of the broken wires.

A detail view to repairs of the broken wires.

A detail view to ferrite cores. Each ferrite core is traversed with three wires. The wires have 0.08 mm in diammeter. The cores have approx. 0.22 mm diammeter.