Differentuating a different logic states/pulses on oscilloscope
Posted: Mon Jun 29, 2020 12:36 pm
Hi All,
Quite new to digital electronics and I'm have trouble telling my highs, from my pulses or my pulse highs!
I'm trying to learn from a functioning Issue 3 board, in order to eventually troubleshoot an issue 1. The issue 1 has ULA issues as no clock on pin 14. I have found useful posts on here (such as this one https://www.sinclairzxworld.com/viewtop ... f=7&t=1851) in which other users have shared what logic state each pin should have on respective chips, specifying Pulse, High, Low, Open, Pulse High, Pulse Low, Pulse High Low. I have a laser logic probe but it doesn't seem to pick up on any pulsing at all!
I do however have an oscilloscope, and I have been examining the ourputs of each pin, but I can't tell the difference between states. I have a feeling that it does not really matter, and the some of the decriptions are nominal, but I'd like to know! Could anyone give me a pointer?
I attach a few pics from the scopes screen when testing pins on the ULA of the working machine
Picture 1 - Pin 1 - High?
Picture 2 - Pin 15 - Pulse High?
Picture 3 - Pin 19 - Pulse?
Thanks and best wishes to all, Will
Quite new to digital electronics and I'm have trouble telling my highs, from my pulses or my pulse highs!
I'm trying to learn from a functioning Issue 3 board, in order to eventually troubleshoot an issue 1. The issue 1 has ULA issues as no clock on pin 14. I have found useful posts on here (such as this one https://www.sinclairzxworld.com/viewtop ... f=7&t=1851) in which other users have shared what logic state each pin should have on respective chips, specifying Pulse, High, Low, Open, Pulse High, Pulse Low, Pulse High Low. I have a laser logic probe but it doesn't seem to pick up on any pulsing at all!
I do however have an oscilloscope, and I have been examining the ourputs of each pin, but I can't tell the difference between states. I have a feeling that it does not really matter, and the some of the decriptions are nominal, but I'd like to know! Could anyone give me a pointer?
I attach a few pics from the scopes screen when testing pins on the ULA of the working machine
Picture 1 - Pin 1 - High?
Picture 2 - Pin 15 - Pulse High?
Picture 3 - Pin 19 - Pulse?
Thanks and best wishes to all, Will