test equipment / Re: Z80 / Z84C Swap (Doh!)
dave.g4ugm at gmail.com
Mon Aug 17 18:29:19 CDT 2015
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of
> drlegendre .
> Sent: 18 August 2015 00:15
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Re: test equipment / Re: Z80 / Z84C Swap (Doh!)
> Hey Dave & All,
> Could you give a little quick kick-start guide to bit depth & sampling rate on
> DSOs? It's always kind of stumped me, not that I've ever read deeply into it..
> but how is it that you can get any kind of (vertical, right?) resolution out of 8
> or even 12-bit samples?
Well the 8-bits is around 5mv on a 1volt signal. It draws a thin line that goes up in big(ish) steps. I am off to bed now but will upload some screen shots to my OneDrive so you can see them.
You need at least twice the sample rate as the maximum frequency you want to plot, but really to be useful I recon 4 x . So the 6022 samples at 48M samples/second and has 20Mhz bandwidth amps so you probably get usefull displays up 10mhz (ish).
> Example line of thought - 8 bit sample = 256 possible vertical positions.
> Even if the screen is low-end (640 x 480) that's almost 2X more height in
> pixels than samples in an 8-bit sample. So each increment is like 2 pixels tall
> and seems like it would be awfully blocky and imprecise. Things would seem
> to get even worse if you try to do maths functions..
> I must be viewing this quite wrong?
> On Mon, Aug 17, 2015 at 3:55 PM, Dave G4UGM <dave.g4ugm at gmail.com>
> > > -----Original Message-----
> > > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of
> > > Noel Chiappa
> > > Sent: 17 August 2015 21:12
> > > To: cctalk at classiccmp.org
> > > Cc: jnc at mercury.lcs.mit.edu
> > > Subject: Re: test equipment / Re: Z80 / Z84C Swap (Doh!)
> > >
> > > > From: Eric Smith
> > >
> > > > If a person has any reasonable business justification
> > >
> > > But a lot of the people here don't; they're purely hobbyists. So
> > > spending
> > $1K
> > > on a piece of test equipment just isn't realistic for them.
> > >
> > > Having said that, I do see some DSO's on eBay for not much money (e.g.
> > the
> > > little hand-held ones), and those might be a good alternative to a
> > > logic analyzer - I never used one, so I tend not to think of them.
> > >
> > > Noel
> > I haven't tried the dedicated DSO's but I have a couple of USB
> > connected ones and a laptop. For value for money I don't think the
> > Hantek 6022 can be beaten. It really only goes to 8Mhz but I see they
> > can be had for $60 - $70 and some sellers have US stock. I also have
> > a 200Mhz one but to be honest for 99% of vintage stuff the Hantek is
> > fine. It is only 8-bit, it is a bit noisy, but its small enough to
> > slip in the laptop bag, it doesn't need a separate PSU...
> > Dave Wade
> > G4UGM
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