Not quite... The end of the ROM based PLA for the 64

[levoman]

I have a cheap usb logic analyzer ( it's only 8 channel ) , never used it yet ,but ,that was my next goto!

Will give it a try and see if it is worth it or not.


Love the scope banman just the sort of thing i like!

[banman]

Hi eslapion,

I have been getting more familiar with the controls. I this time set the trigger level to 1.4V. The sweep time is 100ns and the Volts per division is 500 mV.

Again I am observing a Winbond W27c512 EEPROM.

I should have mentioned that I am running a 10x probe as close as practical to pin10 of the C64 PLA socket. This is referred to as !ROMH.

The machine under test is an unmodified c64 ku-14194hb main board (please be aware in a video I posted here further back I mistakenly said pin13 when in fact it should have been pin10).


Here is a better image. It is remarkably similar to yours now.

The trigger should always be at TTL level or about 1.3-1.5v.

I think this is very important.


Thanks for your patience and sharing your suggestions with us. Much appreciated...

[banman]

Hi levoman,

I have a cheap usb logic analyzer ( it's only 8 channel ) , never used it yet ,but ,that was my next goto!

Will give it a try and see if it is worth it or not.


Love the scope banman just the sort of thing i like!

Thanks. I like it heaps. It's very tactile. I imagine that you feel the same about your Hameg? Which looks good too by the way....

I don't have heaps of cash, I like to keep things on a modest budget. I'm just a hobbyist....

I got mine for $150AUD at a local electronic shop that was shuting down.
All it needed was a new NV ram battery $2 from the same electronics shop I got the oscilloscope.
Have a look online for the ones that don't work. If you see the start up screen shots on the advert displaying all failure errors and look especially for the 6000 error code NV RAM fail. You can be certain that the internal backup battery has gone flat.
All the other errors are related to lost calibration data due to the flat battery.
There are 2 versions. The earlier one has a battery you clip off and replace. Very easy to do (mine thankfully was the earlier version). The later has the NV Dallas ram chips. I hear they can be replaced though there is more work involved. Look on the advert's start up screen it will have a version number and a version date.
Here's mine...look for this revision for the easy battery change out...

Also be sure to replace the X and y class RIFA capacitors (RIFA madness).
There's a few eBay listings if you're interested.

https://rover.ebay.com/rover/0/0/0?mpre ... 2323933672
Dodgy RIFA Capacitors in here....

https://rover.ebay.com/rover/0/0/0?mpre ... 2752829014
Looks like a flat battery...


https://rover.ebay.com/rover/0/0/0?mpre ... 4095451791

Flat battery I think too..

There's plenty of articles on the net regarding getting these back to life. Hey, if nothing else they came keep you warm in winter!
As you can see the folks at Tektronix had a very good sense of humour.....

I think I read somewhere that using a logic analyser is a good way to view logic level glitches.
I saw this interesting video on analogue oscilloscopes...

https://youtu.be/2cteTf7ncDo

I think you've done an amazing job getting this far along.



I am very interested in your glitch testing Zaxxon cartridge. I want to build one...

I have EPROM's very similar to the ones you had success with. I will have a go at testing these.

[eslapion]

The trigger should always be at TTL level or about 1.3-1.5v.

I think this is very important.

I mentioned this in the context of comparing the response speed of 2 different types of PLA programmed with the same logic equations.

In such a case, obviously, you'll want to compare the time difference when output from device A vs device B crosses a certain voltage threshold level.

What you're doing is very different. You're inspecting the specific duration and depth of a down going notch in an otherwise stable logic high signal. This kind of notch can be very unpredictable in intensity or duration so using a TTL level as trigger may be completely irrelevant.

[levoman]

A couple of things have happened this week.

1. The prototype batch of boards have arrived for C64 ZaxxDual and it is working beautifuly!!

2. I have been playing with the logic analyzer and getting some rather odd results which i will share with you once i have investigated a bit more!!

I will be putting the C64 ZaxxDual on PCBWay later so that anybody can get it!

It is on now .

https://www.pcbway.com/project/sharepro ... xDual.html

bin file for dual
https://www.dropbox.com/s/gqoz2lw9zwmuz ... l.bin?dl=0

bin file for zaxx
https://www.dropbox.com/s/o5mu4jtg9nfq70e/zaxx.bin?dl=0

bin file for super
https://www.dropbox.com/s/kgg0uom5kz1yd ... x.bin?dl=0

[banman]

Hi eslapion,


Apologies for mistakingly thinking the trigger voltage of my observations should be TTL level or about 1.3-1.5v.

Your statement was taken out of context.

I must have made a false sense of connection when I saw my trigger level gave the best observations when set to 1.4v.

Hypothetically for example the oscilloscope is reading the voltage on pin10 (!ROMH) of the PLA around the 3.5V to 5V range and the trace drops down when detecting the glitch. Should I set the oscilloscope to trigger on the falling edge of the glitch (I hope I've said this correctly) or is it best to leave it to trigger on a rising edge?



Levoman I just visited the PCB website. Great job on the Zaxxon PLA testing cartridge! I like how you use prescision turned hole sockets....

I am going to order some boards....

[levoman]

Here are a couple of captures to look at and see what you think. The capture is supposed to be 24mhz and the minimum width it seems to be able to 'see' is 42ns. all the small blips and waveform differences are 42ns.

Here is the PLA compared to a PLA while running super zaxxon.

as you can see even PLA to PLA has some differences!

And now the AMD 27c512 uv eprom.

even at this resolution it is showing more differences , however it still runs fine , does not trip the glitch circuit and runs with super zaxxon!!!

What do you think?

I am going to buy a 16 channel 100mhz version ( about £40.00 , a bit cheaper than a digital scope! ).

i almost forgot pla/ is the pla and sub/ is the substitute ( a pla or rom )

[eslapion]

What do you think?

I don't think anything.

The threshold level for these captures is indicated nowhere so there is absolutely no way to tell if they are valid in any way.

Sidenote: Your Zaxxon/Super Zaxxon cart is a good idea but this board is not gold plated so in the long run it can damage a C64's cart port connector.

Hypothetically for example the oscilloscope is reading the voltage on pin10 (!ROMH) of the PLA around the 3.5V to 5V range and the trace drops down when detecting the glitch. Should I set the oscilloscope to trigger on the falling edge of the glitch (I hope I've said this correctly) or is it best to leave it to trigger on a rising edge?

Since you're not looking for a valid logic signal, it shouldn't matter much whether you trigger on a rising or falling edge. I suppose you'd want to start at the highest possible level - around 5V - then turn it down lower and lower as long as you get something.

The lowest level at which you can still get a trigger will show the most serious glitch you can capture.

[levoman]

Sidenote: Your Zaxxon/Super Zaxxon cart is a good idea but this board is not gold plated so in the long run it can damage a C64's cart port connector.

Did you not read the word 'prototype'?

It is a logic analyzer ( ttl levels) and the time is on the top in microseconds , and the time per section is in the bottom right 750ns.

[eslapion]

Did you not read the word 'prototype'?

Cool.

BTW, Thank you very much for posting the binaries.

It is a logic analyzer ( ttl levels) and the time is on the top in microseconds , and the time per section is in the bottom right 750ns.

Logic analyzers can be set for CMOS levels.

The Intronix Logicport which I used to get information on the original 82S100N (and implement these in PLAnkton) can be set to purely arbitrary threshold levels ranging from 0.1 to 4.9V. So it's always better to ask.

And now the AMD 27c512 uv eprom.

What speed rating is it?

I look at your LA captures and I assume the undesirable triggering of the Kernal CS problably stems from some of the inputs changing in the middle of a half cycle as multiplexed lines are connected to the PLA. That's something I saw in the past.

During the VIC-IIs part of the half cycle, only the DRAM and CG are supposed to be accessed. However, you'll sometimes see the BASIC or Kernal CS go low for the early part of the VIC-IIs half cycle as VA12 and VA13 transition from signaling A4-A5 to A12-A13 when CAS goes low.

This also implies the AMD EPROM you have used is probably too slow to do a good job as a PLA. It too should signal a temporary unwanted low on the Kernal's CS.

[levoman]

the AMD uv eprom is 150ns , so yes it is slow. Will have a better look when the 16 channel 100mhz analyzer arrives. I will be able to compare all 8 outputs on both chips at the same time!

And once we get a few reference traces will be able to look at a few more , including the ones that crash the 64.

By the way the HASL finish will not damage the port , but it will need cleaning more often.

Anybody have any experience with HP 54601A? Might have found one with a fault , but an easy fix.

[eslapion]

By the way the HASL finish will not damage the port , but it will need cleaning more often.

If you're going to insert a cartridge with that type of finish only a few times you probably won't have much problem.

However, in the past I had a Super Snapshot V5 cartridge with HASL and it wrecked the cart port connector of the C64 I used it on.

On the cartridge itself, the soft metal scraped off all the way to the copper layer and it started rusting. On the C64 port connector, the gold contacts became coated with the solder layer and they started accumulating carbon until carts wouldn't work anymore.

[banman]

Hi eslapion,

Thank you for the information regarding the triggering on the rising and falling edge when looking at the glitch.

I am following your method and getting good readings.

That doesn't sound like fun with the HASL cartridge connectors.

I am wondering if one could use something like a gold plated cartridge riser permanently in the C64's cartridge port and then use whatever style of cartridge in the riser board.

Could this be a possible workaround, avoiding potentially messing up the delicate cartridge port in the C64…?

I think the issue with PCB'S from PCBWAY is when gold is specified for the cartridge fingers the whole board is plated is gold. I just did a quick check, the price for these boards is astronomical!

Maybe there's a board manufacturer that can just gold plate the fingers.
Could maybe even a local gold electroplating service add gold to just these PCB edge connectors?

[levoman]

Banman wrote

Maybe there's a board manufacturer that can just gold plate the fingers.
Could maybe even a local gold electroplating service add gold to just these PCB edge connectors?

This would require a plain copper finish ( no HASL ) .
If you clean the port now and again with something non-abrasive it should keep ok. I use a wooden coffee stirrer from McDonalds dipped in alcohol or sprayed with contact cleaner , and then a quick spray of wd40 once you have cleaned the connector . You have to keep cleaning it though ( once every 6 months or so ) because the wd40 tends to hold a bit of dust on the connector if left unused , but it does stop the degradation of the connector .

[eslapion]

Banman wrote

Maybe there's a board manufacturer that can just gold plate the fingers.
Could maybe even a local gold electroplating service add gold to just these PCB edge connectors?

This would require a plain copper finish ( no HASL ) .
If you clean the port now and again with something non-abrasive it should keep ok. I use a wooden coffee stirrer from McDonalds dipped in alcohol or sprayed with contact cleaner , and then a quick spray of wd40 once you have cleaned the connector . You have to keep cleaning it though ( once every 6 months or so ) because the wd40 tends to hold a bit of dust on the connector if left unused , but it does stop the degradation of the connector .

Ever heard of ENIG instead of HASL ?