Dual Use of a Timer Module As a Test Device in a Low Cost Crt Workstation
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
A timer device, normally used to time events within a workstation, can also be used to count pulses for purposes of diagnosing outputs of other devices within a workstation or other microprocessor-controlled products. By providing logic to select either a clock signal or other signals to drive a timer, a timer can have a dual purpose. By selecting the CLOCK signal as input, the timer functions as a programmable event timer. By selecting an alternative input, in this example VIDEO, the timer can be used as a diagnostic tool to count pulses coming from another device. The timer can be stopped, its registers read, and compared with an expected value. This capability provides a way to easily test a number of devices within a product through the addition of more selector logic.