microprocessor 'stethoscope'

n microprocessor "stethoscope" It is often necessary to see exactly what logic activity is occurring on the address, data or control busses of a microprocessor system. This is easily done by displaying it on an oscilloscope but not everybody can lay their hands on an oscilloscope at short notice. The "stethoscope" here enables a microprocessor system to be tested without the need for an oscilloscope. Of course it is not intended as the be-all and end-all of test equipment, but then even a doctor"s stethoscope has limitations. "The actual circuit is fairly sïmple. The stethoscope probe is connected to the clock input of a divider. The frequency of the input signal is divided by a certain factor. This factor depends on what output of IC1 is selected with Si and can be between 488.3 Hz/MHz (with Si in position 1) and 15625 Hz/ MHz (Si in position 6). By changing the position of this switch vve can ensure that there will always be an audible output equal to the "divided" input frequ...