公开(公告)号：DE69310277D1

公开(公告)日：1997-06-05

申请号：DE69310277

申请日：1993-06-30

Applicant: IBM

Inventor： GIBBS TERENCE KEITH ,  LUCK GRAHAM ,  EAGLE DAVID JOHN ,  MORRISH ANDREW JOHN ,  FINDLAY VALERIE

IPC: G04F10/00 ,  G04F10/04 ,  G07C3/04

Abstract: An elapsed time recording device includes a counter (130) for incrementally advancing a count value from an initial value towards and beyond a threshold in response to successive clock pulses of a clock signal. Control logic (140) enables the counter (130) to incrementally advance the count value in response to a first input (pin 3) and a second input (pin 1) being at or near a first voltage level, and holds the count value in response to the first input (pin 3) being at or near a second voltage level and the second input (pin 1) being at or near the first voltage level. Setting logic (210) sets the count value to a value beyond the threshold in response to the first input (pin 3) and the second input (pin 1) being at or near the second voltage level when the count value is between the initial value and the threshold. Because the device consists essentially of electronic circuit elements, it can be implemented in the form of an application specific integrated circuit package suitable for high volume manufacture at relatively low cost. The device is therefore favourable for use in mass produced electrical appliances. Because the count value is immediately advanced beyond the threshold in response to removal of the second input voltage, advance of the count value towards the threshold cannot be prevented or delayed by tampering with pin connections of the device.