Another Patron Olny Video - Modding my HP 16500C Logic Analyzer
Added 2020-02-25 21:14:39 +0000 UTCThis is a another video that didn't really go as planned and I didn't really like how it turned out. It's very "rambly" again as well. I'm starting to think more about making more scripted videos now, but that's something I'd rather get into later in a patron update video.
This was me wanting to get my recently acquired HP 16500C Logic Analysis Mainframe ready for usage while filming. It's a very interesting piece of older test gear that's really more computer than anything else. I'm looking forward to getting to know it better and trying it out on future projects because it is very capable despite it's origins being nearly 36yrs old.
I didn't go all out on editing for this one because I wasn't very happy with it towards the end. There is a chance I might go back and try to cut it down a lot more to make it tighter and a better candidate for release.
Comments
Only* :P
Dan Negura
2020-03-07 07:59:20 +0000 UTCI had a feeling it was using a different method of accessing the HDD. CF IDE implimentation is very spotty, hopefully the DOM will work out better. I haven't tried degaussing mine yet. Mine has a slight tine to everything though, degauss likely won't help with that. I didn't really show how many of what I got with my setup. I have two 25/100 state/timing cards withone fully populated with cables and the other with enough for all but one. I think I got 6 pods, not with a full set of clips for each one, but I don't mind because of things like the chip clip or just breadboarding in general. I don't see myself needing a ton of logic I/O soon anyway. The other card does have the external triggering on it. I will probably use that for trying to calibrate that floppy drive because you have to trigger on something other than the data lines. That's goo to know it can work without it though. I've got some standard BNC cables already and I'm probably just going to get some pass-through panel mount adapters and see what happens when I use them. It's really weird that the "solution" was custom probes and I don't really want to pay ebay prices fro them. So I'm going to look around for other options if the added length is a problem. It would be nice to have the protocol conversion, my USB Bitscope can do that, but I don't think I'll need it for most things I do so I don't really mind it being missing from this. I want just for basic logic snooping, so I'm not going to try and hunt down anything like the protocol analyzer. I think you have the right idea awith going for something newer if you really need that. It would be more likely to support new bus types as well then. I'm not sure about the X-Window workaround, I have seen a few people get traces with it: http://spurtikus.de/2016/03/30/hp-16500c-logic-analyzer-information/ & http://www.theresistornetwork.com/2013/12/a-testament-to-x11-backwards.html at least. I'm guessing there is some version in compatiblity somehow. It would be really nice if I could figure out how to make it work because I could do video capture of the scope with the X-Window interface for videos. I may try installing an older linux distro at some point to see if I can make it work. I did move over a ground pin for the final test but was still getting the weird floating issues. I'm not sure what the problem was, I'll go back and try it again later on something else until I can figure it out. I still haven't found a solid answer for triggering, at this point I'm assuming it triggers based on the polarity you set and the order that the traces are listed in. I also have no idea how to use the state mode, but that's a whole other thing... I wish there was a basic "getting started guide" for these assuming no experience at all.
Tech Tangents
2020-03-02 17:14:05 +0000 UTCI've had a 16500C for a number of years and I did the fan and CF card mod too. I had a number of different CF cards of different sizes but only a very old card with 64MB (yes Megabytes) worked. Apparently the system talks to the hard disk in the old Cylinder / Head / Sector mode, not in LBA (Large Block Addressing) mode. So you need an ancient CF card that supports that protocol. 64MB doesn't seem like much but to be honest, that's more than enough space; I've never run into any problems. I only installed one single really quiet fan that I got from Fry's at the time, I don't remember the brand. I checked if it got warmer because of the reduced air flow but no, it's just fine, even the monitor section. And I sometimes run it all day. The only problem with mine is that the degauss circuit seems to be broken so my screen is pink on one side. No biggie. Maybe I'll look into it some day. It's a useful system if you need to analyze a lot of channels. I have something like 128 channels (try to beat that with one of those USB analyzer toy thingies) on two analyzer cards. My analyzer cards have something like 8 pods each with 16 channels and one clock per pod. So I have a lot more pods and probes than you do but I only have 4KB per channel or something. But I can set it up so it pairs up the memory of two pods to get 8KB of buffer per channel but half the number of channels. I also have an oscilloscope card (I don't have whatever that other card is that you have so I'm pretty sure you don't need that unless you want to do external triggering or whatever). I didn't get scope probes with my analyzer and those probes were difficult to find and expensive; most scope probes have wires that aren't long enough because normal scopes have front panel connections. So I had to find original HP probes that cost me an arm and a leg on eBay. I don't think using a BNC extension cable would be an option because of the impedance (I don't really know). The scope is actually not that good if you ask me; I'm thinking of just buying a good scope that can also do some actual logic analyzing, i.e. interpreting SPI and serial and stuff. That seems to be pretty standard as a feature nowadays. What I'm missing on my 16500C is a protocol analyzer: that's a box you can connect externally and is the same size as the mainframe, only much lower. It has no screen or anything else to control it (everything is controlled through the main screen or an X/Window terminal of course) and it's connected via that SCSI-like port on the back side. Without that, you unfortunately don't get very far doing things like reverse engineering. I think any self-respecting analyzer should be able to decode the traffic that goes over a serial, SPI or I2C connection but the 16500C does none of that. There is a symbol editor on board of mine but it's incredibly tedious so basically useless. And I wouldn't be surprised if the external protocol analyzer won't improve on that. I think the protocol analyzer helps you decode things like the instructions that a processor is executing if you probe, say, a Z80 or 6502. But I think you have to either make your own analysis tables or buy them from HP (good luck with that, 20+ years after the system was built). I had it connected to an X/Window server on a Windows XP machine and I also didn't see any live traces. As far as I understand, the 16500C "cheats" during live capture , and writes directly to the screen buffer instead of going through the X11 protocol. That means you will never see any live traces on your remote X/Window screen. Bummer! But you CAN load an existing trace from a file and that WILL show, if I recall correctly. So you can take screenshots that way. Meh, I just use my phone camera. NFS to the 16500C works pretty well too but I don't know if it works with the latest NFS version. You can copy files to and from the hard disk (and floppy drive?) that way. Too bad you have to give the 16500C a fixed IP address (no, it doesn't do DHCP) and I think the network adapter is only 10mbps but oh well. Profiles: If you work on the same project for a while, you can save your profile with a certain name (I think it's AUTOLOAD?) and it will automatically be loaded when it reboots. As for that weird data that you're getting from your TRS-80, that's probably a matter of grounding. Those analyzer pods are REALLY sensitive so if your grounding isn't right, they will go nuts. Use the grounding wire of a pod, not a grounding wire of a probe. If your pod doesn't have a grounding wire, use one from another pod; those probes plug and unplug into the pod.
Jac Goudsmit
2020-02-26 06:22:08 +0000 UTC
