test equipment / Re: Z80 / Z84C Swap (Doh!)

It depends on the screen resolution. My Tek 602, a rather early (and very large/heavy) DSO, does just fine with 8 bits because the screen is fairly small. Compared to the screen resolution of a typical analog oscilloscope screen, 8 bits is a pretty good choice. You can occasionally find DSOs with higher resolution, but there?s a substantial penalty in sample rate. Nyquist rule: you need 2x the sample rate of the highest signal frequency. Or more accurately, the bandwidth. That?s the same thing if you start at 0 Hz, but if you?re sampling a piece of spectrum, you only need 2x the bandwidth of the band in question, not 2x the frequency of the upper edge. Note also that you have to consider filter skirts, so you need 2x the frequency at which your input filter has ?high enough? attenuation. To pick an extreme example, the current record holder DSO has 100 GHz (!) bandwidth and 240 Gs/s sampling rate. You would not display them as 2 pixels tall. Typically the display machinery will interconnect the sample points by lines, and the result usually looks pretty convincingly like an analog scope display (unless you crank the zoom way up). As for math, that depends. If your math involves filtering, the effective bit count goes up (the ?processing gain? DSP people speak of). paul