Browse Prior Art Database

Keyboard Test

IP.com Disclosure Number: IPCOM000086327D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 66K

Publishing Venue

IBM

Related People

Fox, JE: AUTHOR [+2]

Abstract

It is desirable that a diagnostic routine to enable a user to determine whether a keyboard subassembly is functioning properly be provided. This system as it is illustrated, provides a check of the keyboard independently of the utilizing system to which the keyboard is connected, and does so utilizing a minimum of added logic circuitry or hardware.

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Keyboard Test

It is desirable that a diagnostic routine to enable a user to determine whether a keyboard subassembly is functioning properly be provided. This system as it is illustrated, provides a check of the keyboard independently of the utilizing system to which the keyboard is connected, and does so utilizing a minimum of added logic circuitry or hardware.

Fig. 1 illustrates a keyboard system with test function apparatus added. Keyboard 1 contains the normal key buttons or switches in a scanner matrix array. The scanner and electronic controls for the keyboard 1 are not shown. However, keyboard data output on multiple lines indicated as N lines of data, one line for each bit, for example, are illustrated by lines 2 coming from keyboard 1. An output ready or strobe signal line 3 is also provided and an indication that a key has been pressed on the keyboard 1 is normally provided on a line such as line 4.

The using system interface 5 receives the N lines of keyboard output data and the strobe signal, coming respectively on lines 2 and 3, and generates a data received response output on line 6 which is normally used in keyboard 1 to actuate an audible clicker device, to signal to the user that the data has been received at the system interface.

The present test function is embodied in a circuit 7 which is connected to receive the outputs from lines 2, 3, 4 and 6 and to produce two indications on lines 8 and 9. Line 8 is an indication to the keyboard logic to actuate an indication as if a key were actually depressed, and to actuate the clicker 10 by a signal coming on line 9. The clicker 10 is utilized to provide an indication of whether or not the keyboard is functioning appropriately, as will be discussed in greater detail.

Fig. 2 illustrates a specific logic embodiment for the test function circuit 7. The keyboard data output on N lines 2 are applied to four decoding AND gates 11, 12, 13 and 14, respectively. It has arbitrarily been chosen that if two of the keys on keyboard 1 which are normally not depressed together are depressed together, that the signal will be given to commence a test subroutine. The specific keys chosen are the right shift key and the alternate shift key. If the codes for depressing these particular keys are outputted by keyboard 1 on lines 2, AND gates 11 and 12, respectively, will be fully activated.

The output from AND gate 11 is applied to set latch 15 to the on condition which partially activates AND gate 16. If the alternate shift data is next received over lines 2, the alternate shift detecting AND gate 12 will be fully activated and latch 17 will be set to the on condition, supplying a further input to AND gate 16.

If no other keys are detected as depressed, this will be indicated logically by the fact that latch 18 is not set before the Backspace decode is activated. Latch 18 is set by any other key depressed as decoded by AND gate 13; latch 18 will be normally reset by an output from AND gate...