Artifact Details


Whirlwind vacuum tube module rack

Catalog Number



Physical object

Identifying Numbers

Other number 02485 Stamped in blue ink on a white label stuck to the top of the fourth module from the left.
Other number E15-4 Written in ball point pen on a sticker stuck to the left end of back of the upper channel of the rack.
Other number E15-K White on black plastic engraving attached to the right end of the bottom frame member.
Serial number 44? Stamped in white ink on the left end of the upper channel of the rack. The third digit is obscured by a tube module.


overall: 7 3/8 in x 26 in x 12 1/2 in


The rack is built around two identical frame members consisting of a piece of heavy metal that is bent up along one side and down along the other, resulting in an 'N'-shaped channel with a 1.75" bend up, a 2.25" horizontal surface, and a 0.625" bend down. Two of these, oriented in opposite directions, are held together with ten 24-contact edge connectors into which two-tube modules are inserted. Two 11-position screw terminal strips also span the two channels on the right side of the front. Twenty round holes to accommodate BNC connectors are drilled along the front of both channels; however, not all the holes are populated. On the back of the rack, phenolic board with several rows of solder terminals are mounted to the horizontal sections of each channel, and another phenolic board with two rows of solder terminals is mounted perpendicular to bottom one. Two 5-position screw terminal strips are mounted on the left side of the back of the rack, and one 4-position screw terminal strip is mounted to the bottom of the left end of the bottom channel.

About 5 long bus wires are connected to pins of the module sockets to supply common signals and voltages. The two horizontal boards are also wired with two busses each. The vertical board attached to the bottom horizontal board hold the passive components of the rack. Wiring is point-to-point between the solder posts of the boards and the terminals of the module sockets. Some of the wiring terminates at the screw terminal strips. Many of the external wires connected to the screw terminal strips have been cut.

Three brackets that hold two neon lamp sockets each are mounted to the top of the upper phenolic board. Each pair of sockets has a red lens and a clear lens. Dymo labels are attached to the brackets; the labels are upside-down and read, from left to right: "DRUM INT 1,"DRUM INT 2," and "INACTIVITY." A fourth similar bracket holds a potentiometer with a locking shaft.

BNC connectors populate 5 of the 20 holes along the top of the rack. Three of the connectors have a BNC cable that has been cut off attached, and one has a BNC tee, terminator, and a cut-off cable attached. Eleven of the holes along the bottom of the rack are populated with BNC connectors. Six of the connectors have a BNC tee, a terminator, and a cut-off BNC cable attached, and one has a BNC tee and two cut-off cables attached.

All ten module locations are occupied by 2-tube plug-in modules, and all of modules have a tag attached with handwriting in pencil. The module model, serial number, and tag inscription are, from left to right: BA BA# 21, "E15-4-1"; BA BA# 402, "E15-4-2"; FF# 339, "E15-3-3"; GT BA# 506, "E15-4-4"; BA BA# 23, "E15-4-5"; OS CF# 46, "E15-4-6"; FF MOD III# 36, "E15-4-7"; GT BA# 264, "E15-4-8"; FF# 840, "E15-4-9"; and BA BA# 19, "E15-4-10". One module is missing one tube.


Component/vacuum tube


Gift of Compaq Computer Corporation

Lot Number