3 ms·
Debugging this problem in this way was not possible in the time of Alto and became possible in late 80's (with LeCroy DSOs) and really practical in early to mid
by dfox 9y ago
Debugging this problem in this way was not possible in the time of Alto and became possible in late 80's (with LeCroy DSOs) and really practical in early to mid 90's (HP/Agilent) and then cheap relatively recently (chinese DSOs). In the days before that you relied on CRT based scope and tried to make the fault frequent enought to be visible on it.
To some extent this is easier today (but not might be so in few years) because you can buy realtime DSO that is fast enough to capture almost any computer interface used today with usable resolution (albeit you can probably find some successful small-ish hardware startup that would cost you less than such scope)
The art in this kind of debugging is IMHO in using woefully inadequate test equipment to come up with meaningful idea of what might be broken. And this is still done today, with TV repair shops fixing OLED TVs with nothing but DVM and RLC bridge, me looking at 400Mbps+ serial LVDS on customer site with 50MHz portable DSO (they didn't have anything else) and such.
- labcomputer 9y agoI don't see anything in the write-up that requires a DSO--an storage tube (analog) oscilloscope should suffice. Most storage tube oscilloscopes supported single sweep capture in bi-stable mode. That is, you could clear the screen, reset the timebase, and capture the trace of a single trigger event. In bi-stable mode, the image should last hours. Some models (like the Tek 7313) even allowed the top and bottom of the screen to be set to storage or live independently. On top of that, most scope camera shutters could be set up to automatically open during the forward seep (called "single sweep" on Tek cameras). That allows you to set up the scope, and walk away while you wait for the rare event to occur. Tektronix even sold delay lines (big coils of hardline coax) with trigger pick-offs for the express purpose of displaying before-the-trigger waveforms. No question that DSOs make this all easier, but saying it was impossible is a bit of a stretch.