Microprocessor Bus Testers

[TonyDuell]

Sorry, I did mean 'Zicon' Mine is a model 701 logic analyser with an 803 probe/pod.

It looks very similar to the unit you spotted, but is not identical. Mine is also based round the 6802 processor. But I don't have the board of PIAs (?) down the right hand side. There is another board behind the front panel keypad which contains video circuitry, the 701 will display the captured data on a composite video monitor or a UHF analogue TV

[ortek_service]

The same seller who had the L.J.Electronics / Zicon unit, at a Rally the day before I saw the SA2. also had a Thurlby LA-160 (which I did recognise and was once a quite widely-sold fairly low-cost Logic Analyser),

It did have a cracked in half top cover / case screws etc missing, and no probe cables / modules, but I'd always wanted to try one of these and managed to get it for £10, after he'd originally asked for £15.

But when I tried it, I just get all LED display segments light-up and nothing more, as though it's stuck in reset.
However, there is battery-backed RAM with a dodgy? (looks to be leaking) 2.4V 100mAH PCB-Mounted NiCad battery that may well be flat and I'm wondering if that may be stopping a power rail to the RAM etc coming-up enough.
So I will try removing and replacing this to prevent any (further) damage .

I'm not sure if mine is the A (10MHz Max) or B (20MHz Max) version, as there doesn't seem to be a suffix on the model no. on the front / rear, although serial no. does have a -B at the end. Looking in the service manual parts list, it seems the main difference is that many of the fifty IC's - mostly logic - are 74LSxxx on the A version but faster 74Fxxx IC's are fitted to the B version.
But it's not clear whether you could just swap all these to upgrade it, or whether the firmware is different. IIRC, mine does have 74LSxxx ones fitted, although not socketed, so not a quick upgrade. I have readout the firmware from mine and attached this to preserve it in case it's ever needed.

There is an empty socket in mine, that the RS Data-sheet manual says is for another 2764 that gives extra-features and was a user-fit option. So it would be good to get a copy of that, to upgrade it with (once I've got it working).
It would also be useful to find some more info on the external bus buffer / breakout from standard processors boards, to re-make some of these.

There was also a 'Print' / Transfer to PC utility that came with a disc and a couple of EPROM's, so it looks like you needed to upgrade both the original system and the extra facilities firmware for that to work.

Some info & pictures on the LA-160 can be found:
http://mrtomsworld.blogspot.com/2016...alyser_64.html
http://sonicsheep.com/Electronics/2-...y%20LA160.html

With Manuals (also attached) / I found at:
http://www.bitsavers.org/test_equipm...ing_Manual.pdf
http://www.bitsavers.org/test_equipm...60_SERVICE.pdf

[ortek_service]

Originally Posted by TonyDuell

Sorry, I did mean 'Zicon' Mine is a model 701 logic analyser with an 803 probe/pod.

It looks very similar to the unit you spotted, but is not identical. Mine is also based round the 6802 processor. But I don't have the board of PIAs (?) down the right hand side. There is another board behind the front panel keypad which contains video circuitry, the 701 will display the captured data on a composite video monitor or a UHF analogue TV

Thanks, that's useful to know - It looks like L.J.Electronics are using different model numbers to Zicon's original versions (Like with Dataman and re-badge of Elnec etc IC-programmers).

I did, unexpectedly, see there's a 6845 CRTC IC in it. So I'd wondered about it having a proper video output, rather than requiring a'scope to display waveforms on (so like those 16ch 'scope multiplexer projects that used to be around in Electronics magazines etc)

[TonyDuell]

I've got some photos of my Zicon logic analyser here

https://www.flickr.com/photos/tony_d...77720303502148

[ortek_service]

Originally Posted by ortek_service

Thanks, that's useful to know - It looks like L.J.Electronics are using different model numbers to Zicon's original versions (Like with Dataman and re-badge of Elnec etc IC-programmers).

I did, unexpectedly, see there's a 6845 CRTC IC in it. So I'd wondered about it having a proper video output, rather than requiring a'scope to display waveforms on (so like those 16ch 'scope multiplexer projects that used to be around in Electronics magazines etc)

Originally Posted by TonyDuell

I've got some photos of my Zicon logic analyser here

https://www.flickr.com/photos/tony_d...77720303502148

Thanks for the info and link to those photos of yours, which I've been comparing to the one I saw.
The main board does look rather-similar, but whilst yours only has one (part no. 27017 Date 870114) EPROM fitted, with an empty socket above this.
Whereas the one I'd found has a later (part no. 27037 Date 8?90126), plus an extra (part no. 2704? Date 890126?) EPROM fitted above that.
- So maybe that extra EPROM provided extra facilities / was for the additional expansion board?

It does seem that the extra expansion board on the one I saw, is connected in place of one of the (many!) original 6821 PIA's, and has even more on this board (+ some RAM IC's?). So I'm wondering if this provides extra channel inputs?

Unfortunately, there doesn't seem to be much info on the 'net about either Zicon or L.J.Electronics (unlike the Thurlby LA-160, with both manuals online and websites like sonicsheep.com + mrtomsworld.blogspot/2016/08 having some useful info on these)

Although I've found the Zicon 801 model (with built-in Green-screen CRT), does seem more-common than the 701 you've got.
And I've seen similar-looking Interface pod modules people have for their 801, to your 803 one - So maybe the 803 was also originally intended to be used with the 801, and they'd retained the same connector (Like Polar B2000 & B200A etc).

I did find the L.J.Electronics Ltd. model SA 1 (/ Zicon Model 632) Service Manual is also held here:
https://elektrotanya.com/l.j.-electr.../download.html - Which can be a bit-easier to download from.
Where I see that on the manual's front, it says 'Distributed by L.J.Electronics' (in Norwich). And 'Designed & Manufactured by Zicon Instruments Ltd' - also in Norwich (but at a different address / 'phone number).

The elektrotanya.com website also described the SA 1 / L.J. Electronics 632 as a 4MHz Clk Logic Analyzer 1981. So it looks like that was an older / slower version and lacked the video display (plus built-in disassembler etc?) that the Zicon 801 (L.J. Electronics SA 3 ?) (and Zicon 701 / L.J. Electronics SA 2 ?) had.

That SA 1 / Zicon 632 manual also has a schematic for their 16ch Input Buffer Pod, which they may have carried-on using with later ones.

[ortek_service]

Originally Posted by ortek_service

>> also had a Thurlby LA-160 (which I did recognise and was once a quite widely-sold fairly low-cost Logic Analyser),
>>
But when I tried it, I just get all LED display segments light-up and nothing more, as though it's stuck in reset.
However, there is battery-backed RAM with a dodgy? (looks to be leaking) 2.4V 100mAH PCB-Mounted NiCad battery that may well be flat and I'm wondering if that may be stopping a power rail to the RAM etc coming-up enough.
So I will try removing and replacing this to prevent any (further) damage .

I'm not sure if mine is the A (10MHz Max) or B (20MHz Max) version, as there doesn't seem to be a suffix on the model no. on the front / rear, although serial no. does have a -B at the end. Looking in the service manual parts list, it seems the main difference is that many of the fifty IC's - mostly logic - are 74LSxxx on the A version but faster 74Fxxx IC's are fitted to the B version.
But it's not clear whether you could just swap all these to upgrade it, or whether the firmware is different. IIRC, mine does have 74LSxxx ones fitted, although not socketed, so not a quick upgrade. I have readout the firmware from mine and attached this to preserve it in case it's ever needed.

There is an empty socket in mine, that the RS Data-sheet manual says is for another 2764 that gives extra-features and was a user-fit option. So it would be good to get a copy of that, to upgrade it with (once I've got it working).
It would also be useful to find some more info on the external bus buffer / breakout from standard processors boards, to re-make some of these.

There was also a 'Print' / Transfer to PC utility that came with a disc and a couple of EPROM's, so it looks like you needed to upgrade both the original system and the extra facilities firmware for that to work.

Some info & pictures on the LA-160 can be found:
http://mrtomsworld.blogspot.com/2016...alyser_64.html
http://sonicsheep.com/Electronics/2-...y%20LA160.html

With Manuals (also attached) / I found at:
http://www.bitsavers.org/test_equipm...ing_Manual.pdf
http://www.bitsavers.org/test_equipm...60_SERVICE.pdf

Well I later found there is some more quite-useful info, on a linked sub-page in one of the above links, at:
http://sonicsheep.com/Electronics/3-LA160%20Writeup.htm

Plus downloads of some versions of the firmware, at http://sonicsheep.com/Electronics/Downloads.html
Although only versions 33 & 50 of the main firmware, rather than all the ones he'd said he'd copied so far:

I have the following versions of main ROM copied,
160A 01 - specific to 10MHz hardware
160B 01 - specific to 20MHz hardware
160 32
160 33
160 50

and not the extra-facilities EPROM (which it seems the PC software needs version 50 of both that and the main one to work, so originally came supplied with these).
- As well as a PC Program for later OS's, that he'd written.


I've found that the unit first tests the all the display segments, but it should then start showing version info etc which I can't get it to do. The 2.4V 100mAh NiCad backup battery is flat in mine, but it hasn't failed s/c - maybe o/c, as there's 3.6V across it when powered up and doesn't draw any current if I connect a bench-PSU, set to 3.6V directly to it.
So I need to do some more fault-finding investigation on this.

I've also discovered that the original version (01) firmware (that I have in my early-version unit), has an A / B suffix version to go with what speed IC's etc. the h/w is using. But on later ones, it asked the user to enter A or B, if the battery-backed RAM had lost this setup config value.

Plus, I found that my unit fortunately is actually the 20MHz 'B' version. So I don't need to try and de-solder 22off! 74LS etc IC's and change them to 74Fxxx / 74Sxx ones (as well as changing 4off resistors & 6off capacitor values + Crystal) - and also swap the firmware on my early-model - in order to 'upgrade' to the faster 'B' model.
I do wonder if they really saved that much cost with using the 'standard version IC's, to have ever produced the 10MHz 'A' model - as it still has the same total number of parts as the the twice-as-fast 'B' version.