APPLICATION
KEYBOARD CONSTRUCTION
This keyboard is constructed of three parts on the top surface (ref. Fig. 4-1). A 6 position turning key switch area is at the upper right corner, a 14 x 8 matrix of push key switches occupies most of the top surface and a left-right slot near the upper edge is designed for the Magnetic Stripe Reader of the -M2, -M3, -MJ models.
In the rectangular area at upper right corner there are one 6 position electronic key switch and two LED’s. The left LED is for MSR indication and the right LED between the turning key switch and the MSR indicator is the power-on indicator. The 6 position electronic key can be turned to one of the following 6 positions: LP, L0, L1, L2, L3 and L4. It can only be taken out from the switch at positions L0 and L1. The purpose of this electronic key serves 3 folds: When the key is switched to (and extracted from) position L0, the whole keyboard output will be blocked off by hardware to work as a security measure. A programmable answer back code for the final position of the 6 position electronic key will be sent by the keyboard to the host computer whenever the key is switched to a new position for a programmable delay time or when the host computer sends a specific code (E7h) to inquire the keyboard. The position of the electronic key determines which page of the key content table for the 112 push keys applies, while the definitions of the same key within different pages can be programmed so absolutely independent to provide instant menu change over.
Power-on LED | 6 position key |
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MSR indicator | 6 position key switch |
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MSR slot
14 x 8 push keys
Fig. 4 - 1
TM