Looking at doing z80 hobby work, is a logic analyser worth it? - Page 1
Forum section: electronics / beginners

author: NRoach44
author_rank: Contributor
timestamp: December 18, 2014, 12:53:18 am
content: Basically as the title. I'm interested in building a z80 computer and getting into things like that. I don't think I'll get too far deep into protocol territory with my arduino stuff, so I don't foresee needing protocol analysis. So the stuff I'm going to be working with immediately is up to 10 MHz, ~28 ch TTL.One thing I have considered is using my nucleo (ARM arduino competitor) as a simple USB Console bus status follower (I.E. it just dumps the status of the bus to a console). The other thing is, is the logic analyser scene like the scope scene, where the PC attached versions are useless, or are they half-decent? Bear in mind I'd need linux compatibility if you recommend a pc scope (or it should be capable of running in a VM).I've found on ebay:(generic?) Hitachi VC-3130http://r.ebay.com/15m8OO(~$150 shipped)HP 1662Chttp://r.ebay.com/PL4bl9(~$250 shipped, + ~$50 to complete)I'm interested in the networking capabilities of the HP, but realise getting either the option or a unit with it is more expensive or nigh on impossible. My nucleo idea does present a challenge in the fact that I'm pretty inexperienced when it comes to programming, and if I use a separate device as the clock source it could present some interesting hurdles.Thanks!

author: NRoach44
author_rank: Contributor
timestamp: December 18, 2014, 04:03:36 am
content: Cheers wlfred!I've had a look around and even installed sigrok from the debian repos, and those USB ones seem like an acceptable alternative. Although even if I probably didn't need it I'd still like to be able to see the whole 24 channels.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 18, 2014, 05:09:40 am
content: I have one of those little OpenBench logic sniffers and it's been perfect the few times I've needed it. I've been using sigrok with it under Kubuntu (mostly Windows free since '06.)It's not something you really need very often or possibly at all. Back when Z-80 hobbyists were really at it, we didn't have any kind of LA. At least the vast majority of us. Maybe a logic probe.

author: NRoach44
author_rank: Contributor
timestamp: December 18, 2014, 05:25:34 am
content: Alright, thanks guys! I'll try out one of the cheapies from aliexpress. Now I've just got to put together a nice little logic shifter for it.

author: tggzzz
author_rank: Super Contributor
timestamp: December 18, 2014, 12:48:42 pm
content: When using a logic analyser with a Z80 30 years ago, I found it very useful to use the "state capture" modes.In those the LA does not use its own internal free-running clock. Instead it only captures a sample when the Z80's clock changes and various Z80 control lines are in selected states. That makes it easy synchronise your observations to whatever the Z80 is doing, and to filter based on address range, instructions executed etc.Some cheap LAs "state capture" mode can be much slower than their free running mode.Some cheap LAs have suboptimal grounding (especially w.r.t. clocks) which might lead to signal integrity problems.Of course, if you have a "slow" Z80 controlling "fast" logic, then your requirements might be based on the fast logic's performance. But you've already taken thatinto account!

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: December 18, 2014, 05:08:27 pm
content: as someone building a single board z80 too, yes logic analyser is well worth it.8 lines imo, not enough. 16 is crunchy. 32 would be awesome.you need to see the cpu control pins (ioreq/mreq/wait/m1), sometimes all the data pins / address pins. having to change the fling leads all the time you want to test something is a pin.The best bet is a Z80 ICE that plugs into the z80 socket. (_IF_ you are using a DIP Z80 cpu)

author: nfmax
author_rank: Super Contributor
timestamp: December 18, 2014, 05:54:24 pm
content: I have an Intronix LogicPort USB-based logic analyser, which has 34 channels of state and timing, albeit with a restricted memory depth. I have used it to play around with a 6809 board, and it has just the right 'width' for an 8-bit system.I also have a Nicolet NICE+ Z80 ICE which I acquired many years ago. It basically works, but seems very fussy about its RS-232 voltage levels. What I don't have is a manual. I have tracked down the manual for the original NICE, but the NICE+ has internal RAM which can be mapped to the target and I don't have any documentation for the corresponding commands. Anyone out there have this information?

author: marshallh
author_rank: Unknown
timestamp: December 18, 2014, 05:55:24 pm
content: The older late 80s LAs have built-in instruction decoding and disassembly for watching Z80 busses and the like. They can be gotten cheap now.