NCR 5953 manual Double-High / Double-Wide Keys

5-6 Chapter 5: 5953 USB DynaKey Migration

The USB DynaKey implements a standard seven-port USB Hub internally, which provides independent connectivity to the several functional sections that comprise the DynaKey.

Both USB and Wedge NCR DynaKeys include keys that accept customer-specified key caps and labels. For example, one customer may wish to include buttons for DEPT, CLASS, and SKU on his keyboard. A different customer may have no use for these keys, but may want TIRES, BATTERIES, and ACCESSORIES on specific keys. Capable keys provide for this customization.

Double-High / Double-Wide Keys

With capable keys you can put caps over pairs of plungers, resulting in larger keys. On a standard keyboard, the space bar, the Enter, Tab, Delete, Shift, Control, and Alt keys are all wider than the rest. These keys are implemented with one or two plungers, but they cannot be modified for different functionality. On NCR keyboards, the capable keys may be capped in pairs. Key caps are available that cover two plungers, either double-highor double-wide.

When two keys are capped individually, the keyboard firmware must detect each one as a different key, and must send different messages to the host computer to indicate that different keys were pressed. When the same two keys are capped together, the firmware must know this and send only one message. With the 5953 Wedge DynaKey, this is accomplished by using firmware that senses both plungers and the time lag between the plungers. If adjacent plungers are pressed within a certain interval, then the firmware only sends one of the two. Which one it sends is fixed, and the time lag is fixed. Thus, although this method works, it is subject to occasional error due to small mechanical tolerance problems. It is also somewhat limited in flexibility.

With the 5953 USB DynaKey, the keyboard is fully programmable. Two keys that are capped together can be programmed to literally be the same key. (Duplicate messages are discarded.) Thus there is no limit to the flexibility, and no problem can be induced by the same minor mechanical problems experienced with the 5953 Wedge DynaKey.