Displays

Revised 20 August 2004
Thanks to Todd Robinson for his insights and for pointing out that this display technology is used in the Family Feud.

5x7 Electromagnetic Flip-Dot or Flip-Disc Display
Ferranti-Packard Assy 303170-003
FP599 28670-01A

Quantity (4) removed from a parking lot exit cashier's booth. The display panel reads "PAY THIS AMOUNT."
Please email me if you know how to drive these or if you have any you'd like to part with!

These units are similar to electromagnetic core memories used in early computers, where ferrite beads stored 1s and 0s as opposing magnetic polarities. Core memories could be written and read electronically, whereas flip-dots can be written electronically but must be read visually. The fact that a character set is pre-wired into this particular flip-dot module evokes comparison to rope core memory, where the wiring was used to store read-only data.

Two boards are shown in the photo above. At the bottom, the front of the board is shown, consisting of a 5x7 array of metal disks, each of which can show either its "black" or "orange" face. At the top, the wide edge of the board is shown revealing the massive threading of copper wires through the open topped "figure-8" shaped magnetic cores.

ddd

On the front, each display element consists of a magnetic disk, painted black on one side (now rusty) and fluorescent orange on the other. Each disk is free to rotate around two points (at 4:00 and 10:00 in the photo above). Each disk is held in its default (black) position by a magnetic field created by two poles (at 1:00 and 7:00 in the photo above). There are no springs or other elements on the display side of the board. The two poles that are visible may be envisioned as the tops of a "U" in what otherwise would be a "figure-8" shaped magnetic core where the upper loop of the "8" is opened to form a "U" instead of an "O." Current flowing in the upper or lower windings will switch the magnetic polarities of the core and cause the disk to flip, revealing its bright or dark side.

Two boards are shown in the photo above. At the bottom, connections are shown for the prewired figures "1" through "0." "COM" is evidently the common antipode to each while the purpose while the connection "B" probably blanks the display. The individual dots are not addressable. At the top, wires can be seen threaded through the upper and lower loops of the "figure-8."

The "U/8" loop seen face on. Notice that multiple turns of fine copper wire run through each loop.

The "U/8" loop seen from the side. Notice the smaller bundles of wire, each one probably holding the number of turns required to active a single character.

5x7 Electromagnetic Flip-Dot or Flip-Disc Display Ferranti-Packard Assy 303170-003 FP599 28670-01A Quantity (4) removed from a parking lot exit cashier's booth. The display panel reads "PAY THIS AMOUNT." Please email me if you know how to drive these or if you have any you'd like to part with! These units are similar to electromagnetic core memories used in early computers, where ferrite beads stored 1s and 0s as opposing magnetic polarities. Core memories could be written and read electronically, whereas flip-dots can be written electronically but must be read visually. The fact that a character set is pre-wired into this particular flip-dot module evokes comparison to rope core memory, where the wiring was used to store read-only data.
Two boards are shown in the photo above. At the bottom, the front of the board is shown, consisting of a 5x7 array of metal disks, each of which can show either its "black" or "orange" face. At the top, the wide edge of the board is shown revealing the massive threading of copper wires through the open topped "figure-8" shaped magnetic cores.	ddd On the front, each display element consists of a magnetic disk, painted black on one side (now rusty) and fluorescent orange on the other. Each disk is free to rotate around two points (at 4:00 and 10:00 in the photo above). Each disk is held in its default (black) position by a magnetic field created by two poles (at 1:00 and 7:00 in the photo above). There are no springs or other elements on the display side of the board. The two poles that are visible may be envisioned as the tops of a "U" in what otherwise would be a "figure-8" shaped magnetic core where the upper loop of the "8" is opened to form a "U" instead of an "O." Current flowing in the upper or lower windings will switch the magnetic polarities of the core and cause the disk to flip, revealing its bright or dark side.	Two boards are shown in the photo above. At the bottom, connections are shown for the prewired figures "1" through "0." "COM" is evidently the common antipode to each while the purpose while the connection "B" probably blanks the display. The individual dots are not addressable. At the top, wires can be seen threaded through the upper and lower loops of the "figure-8."
The "U/8" loop seen face on. Notice that multiple turns of fine copper wire run through each loop.
The "U/8" loop seen from the side. Notice the smaller bundles of wire, each one probably holding the number of turns required to active a single character.