POSIFLEX Business Machines PST KB136 manual Answer Back Code, Hardware Limitation

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any other displayable key stoke – will be taken as an input in scan-code format.

any other non-displayable key stroke – will have no influence

ANSWER BACK CODE

Programming the answer back codes of the 6 position electronic key-lock is also very easy as they are included in the keyboard programming with the locations coded as “KLP”, “KL0”, “KL1”, “KL2”, “KL3” and “KL4” in the key-layout map of page L1. The programmable keyboard will issue an answer back code to PC whenever the 6 position electronic key is switched to a new position or when the keyboard receives an “enquiry” code (E7h) from the PC or the PST system. A time delay as determined in the configuration of the keyboard programming utility is adjustable by “r” and “t” key presses, this time delay is useful to give only the answer back code of the last position of control key when it is turned across several positions. Here are some examples of sending this “enquiry” code in different languages:

Language	Syntax
C	outp (0x60, 0xE7)
BASIC	out &H60, &H0E7
DEBUG	o 60 E7

HARDWARE LIMITATION

In case of “multiple combination key” application which means pressing three or more keys at the same time to obtain certain data output from the keyboard, there could be some limitations inherent from the nature of keyboard structure. The CPU of keyboard detects the contact between the “horizontal” and “vertical” lines for each key press, recognizes which key is pressed and sends correspondent data to the host computer. When there are many keys pressed at the same time, and the pattern of the contacts coincides with some special relationship, there are chances that the CPU of keyboard be confused about exactly which keys are pressed. The user may change the locations of the key-definition to prevent this once such confusion happens.

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