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How to test memory?

That is an impressive unit. I assume when you say it can test anything you are talking about single chips and not modules (i.e. SIMMs, SD-RAM, etc.). Di you build it yourself?
 
Shadow Lord said:
That is an impressive unit. I assume when you say it can test anything you are talking about single chips and not modules (i.e. SIMMs, SD-RAM, etc.). Di you build it yourself?
Click to expand...

Well, I am collecting old arcade machines, so I have to test e.g. 256x4 SRAMs and similar "small" chips. The tester tests single chips only and is focused on SRAMs and DRAMs from the 1970s/1980s - no SIMM, no SIPP or other modules can be tested. But you can also check logic chips and it has some nice features to check ROMs/EPROMs.

Yes, I build it myself. You get two PCBs: the main PCB and a DC/DC-module PCB. The Atmega was pre-soldered, so there was no need to solder it myself. All other components are THT.

The developer has usually only a few PCBs on stock, so you might have to wait a few weeks until he ordered a new batch. But he might have older revisions if you are fine with switches.
 
Damn, tried to cite and to preview a message from the developer and posted it accidentally. Had to wait until a mod approved it.

So 2nd try:

I got this info, so he sells pre-soldered PCB only:
When someone is interested in the "new" Tester:
I have updated the manuals (available in German and English) downloadable from my website:
https://8bit-museum.de/sonstiges/har...te-chiptester/

btw: There is no need to solder the ATmega yourself since I order the PCB (only the ATmega) professionally pre-soldered.
Click to expand...
 
Damn, tried to cite and to preview the text above and accidentally posted it. Tried to re-post the message but that didn't work (a mod has to approve it).

That is what I got from the dev:
When someone is interested in the "new" Tester:
I have updated the manuals (available in German and English) downloadable from my website:
https://8bit-museum.de/sonstiges/har...te-chiptester/

btw: There is no need to solder the ATmega yourself since I order the PCB (only the ATmega) professionally pre-soldered.
Click to expand...
So PCBs are always pre-soldered.
 
euro22 said:
Damn, tried to cite and to preview the text above and accidentally posted it. Tried to re-post the message but that didn't work (a mod has to approve it).

That is what I got from the dev:

So PCBs are always pre-soldered.
Click to expand...

Except there is no shipping to US unless you want to pay 40 Euros to ship two PCBs.
 
Shadow Lord said:
Except there is no shipping to US unless you want to pay 40 Euros to ship two PCBs.
Click to expand...

I checked DHL
https://www.dhl.de/de/privatkunden/kampagnenseiten/coronavirus.html#usa

This is temporary only, because of Corona.
Google Translated:
The transport capacities to the United States of America are currently considerably reduced, so that the sending of letters and parcels can only be maintained with special measures.
The dispatch of goods and (small, <2kg) parcel shipments to the USA is no longer offered until further notice
For private customers: For the time being, shipping of parcels to the USA is only possible for parcels in connection with the Premium service.

:(
 
I don't see any specifications about timing margins. Does it state where static RAM begins to fail, using different edges? Does it report where DRAM begins to have issues with refresh. Testing RAM is not go/nogo type testing.
The best test bed for the RAM found in your system is the system it is in. Learn to write simple test code using the resources in your system. It is the best way to tell you if the RAM is working in your system.
Dwight
 
euro22 said:
I checked DHL
https://www.dhl.de/de/privatkunden/kampagnenseiten/coronavirus.html#usa

This is temporary only, because of Corona.
Google Translated:
The transport capacities to the United States of America are currently considerably reduced, so that the sending of letters and parcels can only be maintained with special measures.
The dispatch of goods and (small, <2kg) parcel shipments to the USA is no longer offered until further notice
For private customers: For the time being, shipping of parcels to the USA is only possible for parcels in connection with the Premium service.

:(
Click to expand...

Yes, supposedly temporary. But I would think there would be more services then DHL from Germany for delivery. Oh well. I am in no rush. He has one saved for me in the next batch.

I am currently more focused on ordering stuff from China... If things continue as they are cheap components are going to disappear soon...
 
Dwight Elvey said:
I don't see any specifications about timing margins. Does it state where static RAM begins to fail, using different edges? Does it report where DRAM begins to have issues with refresh. Testing RAM is not go/nogo type testing.
The best test bed for the RAM found in your system is the system it is in. Learn to write simple test code using the resources in your system. It is the best way to tell you if the RAM is working in your system.
Dwight
Click to expand...

You're right. Of course that would be wonderful if a tester checked all the timings (several dozen for DRAMs).
But does that matter at all? We are talking about 40-45 year old memory modules. Material fatigue is no longer so important for so old chips, if they are defective, then they are really defective.
The developer describes in his manual that these tests are not possible with the cheap AVR chip (60ns per instruction). It would take a much faster chip and expensive hardware to test timings. Did I mention that the chips to be tested are over 40 years old? And I do not want to pay thousands of dollars for a testing device?

In my opinion, testing in a machine is not a good idea. I am always afraid that if I switch on one of my pinball machines or arcades, something will break again. Testing 10 or 20 modules alternately would not be a good idea at all.

But to quickly test a memory ic, that's practical. And I have found no other way to test some "exotic" chips.

And why should I code (e.g. a pinball machine) to test its RAM (and how?)? Most systems do a RAM test when switched on (even my pinball machine from 1974) or an Atari ST or Sinclair ZX Spectrum, but then just crash without saying which RAM is defective.
 
Shadow Lord said:
Yes, supposedly temporary. But I would think there would be more services then DHL from Germany for delivery. Oh well. I am in no rush. He has one saved for me in the next batch.

I am currently more focused on ordering stuff from China... If things continue as they are cheap components are going to disappear soon...
Click to expand...

I want to know now ...
https://my.dpd.de/sending/sendparcel.aspx -> USA will not be delivered at all
https://www.gls-one.de/de/parcel/ -> USA will not be delivered at all
https://www.myhermes.de/ -> USA will not be delivered at all
You can check the drop down boxes for possible destinations.
And the last one UPS: UPS Expedited, 78.05 EUR

Racing pigeons should still be possible.

Very interesting the impacts of corona.
 
DeltaDon said:
How many boards can be in one package at the 78.05 rate? If 10 or so boards then dividing the shipping costs would be about $8 for each board. Less if even more boards in one package.
Click to expand...

Yeah, that is to get it to the US. Then you have to spend $10-$12 per board to get it shipped in the USA unless everyone is local and can come by and pickup their boards. Once things et back to normal shipping should be about 9 Euros per board to USA (w/o tracking).
 
euro22 said:
You're right. Of course that would be wonderful if a tester checked all the timings (several dozen for DRAMs).
But does that matter at all? We are talking about 40-45 year old memory modules. Material fatigue is no longer so important for so old chips, if they are defective, then they are really defective.
The developer describes in his manual that these tests are not possible with the cheap AVR chip (60ns per instruction). It would take a much faster chip and expensive hardware to test timings. Did I mention that the chips to be tested are over 40 years old? And I do not want to pay thousands of dollars for a testing device?

In my opinion, testing in a machine is not a good idea. I am always afraid that if I switch on one of my pinball machines or arcades, something will break again. Testing 10 or 20 modules alternately would not be a good idea at all.

But to quickly test a memory ic, that's practical. And I have found no other way to test some "exotic" chips.

And why should I code (e.g. a pinball machine) to test its RAM (and how?)? Most systems do a RAM test when switched on (even my pinball machine from 1974) or an Atari ST or Sinclair ZX Spectrum, but then just crash without saying which RAM is defective.
Click to expand...

First, don't use cheap AVR chips use cheap Arm chips. They can generate signals on pins from timers at rates of faster edges than 50MHz. They can trigger interrupts or timer inputs as similar rate. Many have instruction clock rates of around 300MHz.
Cheap BluePills are under $2 but are limited close to 72MHz. This includes the processor and device end USB with RAM onboard that can be used as DMA. The 407 series has more and better of everything.
Still, I'm finding it easier to put test code on EPROM. This should work well for everything except my Genie that uses those Rockwell chips ( that has a problem of slow oscillator startup. I'm thinking of replacing the crystal oscillator with a can oscillator. It blows a fuse on powerup ).
Dwight
 
Dwight Elvey said:
First, don't use cheap AVR chips use cheap Arm chips. They can generate signals on pins from timers at rates of faster edges than 50MHz. They can trigger interrupts or timer inputs as similar rate. Many have instruction clock rates of around 300MHz.
Cheap BluePills are under $2 but are limited close to 72MHz. This includes the processor and device end USB with RAM onboard that can be used as DMA. The 407 series has more and better of everything.
Click to expand...

Don't these boards use 3.3v so you have to use logic level converter?
 
euro22 said:
Don't these boards use 3.3v so you have to use logic level converter?
Click to expand...

They use a 5V to 3.3v converter. 16 of the I/Os are 5V tolerant ( at least for the BluePill ). For input TTL or CMOS is fine. For outputs it is recommended to use them as open drain and a pullup resistor. The B/C port is 3.3v only. Still, a HCT part will work fine to drive signals ( a little on the low end for TTL high though ).
Dwight
 
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