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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 25th Apr 2021, 5:48 pm   #1
ScottishColin
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Default RAM / ROM tester

I have no affiliation with the person/people who have created this - I thought it might be of interest to those on these forums.

There isn't a price I can see, but it looks there is a contact form on the web page.

https://8bit-museum.de/sonstiges/har...ester-english/

Colin.
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Old 25th Apr 2021, 11:41 pm   #2
ortek_service
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Default Re: RAM / ROM tester

That's an interesting one, I hadn't seen before. But at least they provide the firmware binary file for it, even if they don't give the source-code / or the schematics? for it. It looks like it supports lots of devices - albeit with the use of pin-adaptor modules.


I had previously seen something similar, that used various extra 'blade' plug-in modules to support groups of similar devices - but maybe not as many and mainly focussed on those used in arcade machines compared to the one you'd found. This was called the Inquistor (originally designed by NeoLoch - who've now sold it to Pinball Classics). About half-way down products page: http://www.lockwhenlit.com/products.htm

But there isn't much info about it there, although the original designer still has some of the instruction guides: http://www.neoloch.com/
(And who'd done a previous less-versatile (RAM-only?) one, before this: http://www.neoloch.com/products/NLT-28P-LCD-5S.php )

Pinball Solutions also used to sell the Inquisitor / have instruction downloads, but it seems they've now discontinued it: http://www.pinballsolutions.eu/produ...ls/inquisitor/
However, they do sell another similar idea product: https://www.pinballsolutions.eu/prod...a-riot-tester/


In view of the amount of these that seem to get rapidly discontinued and no longer supported, an open-source one would be ideal that various people can update with extra devices - A bit like some old commercial ABI Electronics etc. IC testers, that you could write your own test files to support odd devices. But these are quite expensive and sought-after by arcade-machine repairers. Newer ones are still quite expensive: https://www.abielectronics.co.uk/Pro...ChipMaster.php
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Old 26th Apr 2021, 4:56 pm   #3
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Default Re: RAM / ROM tester

I used to use a software solution for testing the RAM on Sinclair computers. The program wrote to every memory bloc and then read back the data. If the written data did not match the read data it displayed the problem memory bloc. Of course you still needed to know which bloc was in each RAM chip. The software was in Sinclair basic. You could use the same method for other computer types but ideally you need a doner computer to fit sockets in for the RAM under test and the software program to do it.

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Old 26th Apr 2021, 8:16 pm   #4
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Default Re: RAM / ROM tester

On Sinclair (Spectrums at least), the ROM actually did a RAM-test at reset and recorded the highest usable RAM location in a couple of Bytes in the system variables.
So you could just peek those locations, multiplying the high Byte by 256, to check if you had the full 48K / only the first 16K was there or somewhere in between. And by Poking 0 & 255 into the location that failed, you could then find which databit(s) the faulty RAM(s) were on.

This does assume that the 16K 4116's were all working good enough, to allow the computer to run. So I used to just end up socketing them all, if it looked like there were faulty ones, and putting known good ones in to start with, before swapping originals back one at a time.
However, I've recently been playing with Diagnostic ROM's for these, that use coloured Red / Green bars in the border to indicate faulty ones and save some work.

However, this only lets you test the RAM types supported by the computer, and so no good for testing other types. And therefore need something else like a simple Arduino shield add-ons you can build. Or even buy a complete tester module on the 'bay etc. for around £20.
But many are still restricted to the common 4116's & 2114 types.

Therefore a more universal one is rather useful. For ROM's, you can normally use most EPROM Programmers, with a suitable DIY adaptor for odd-pinout types. But RAM's & PIO's etc. need something that allows you to run test vector routines on.
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Old 10th Aug 2021, 10:21 am   #5
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Default Re: RAM / ROM tester

I have one of these German retro chip testers.

It comes as a PCB with the Atmega chip and crystal pre-soldered, and a separate piggyback PSU PCB for 36 euros. The Atmega is already programmed with the firmware; new versions of the firmware can be uploaded with a cheap usb programmer. The board is well made although some of the holes are a bit small for the diodes, whose leads also have to be bent very close to the body. Not sure why they didn't just use SMD devices.

You need to find all the parts yourself; I think there is a complete order list for a German supplier, else you'll need to find bits from RS, Farnell and eBay. But there's nothing really odd needed.

It can test not only srams, drams, roms etc but also TTL logic, and can dump ROM contents to a SD card if needed. A very handy gadget to have.
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Old 10th Aug 2021, 10:39 am   #6
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Default Re: RAM / ROM tester

That appears to be the same unit Colin referred to in his first post. Just in the past week I came across a video or blog of someone putting one together and trying it out, but of course I don't remember where. I'll post the link if I can find it again.
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Old 10th Aug 2021, 8:07 pm   #7
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Default Re: RAM / ROM tester

This one probably https://www.youtube.com/watch?v=_99HNsxgLRw
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Old 11th Aug 2021, 9:40 am   #8
Michael Haardt
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Default Re: RAM / ROM tester

If you want open source, the minipro/TL866 with the Linux front end software minipro might be an alternative. I just saw that the functionality to control inputs and outputs is integrated in the main branch.

Special code for certain TTLs or certain SRAMs is probably not too hard to write, see tl866iiplus_pin_test() in tl866iiplus.c.

DRAMs will not be possible, because the timing is too slow and cannot be controlled. That would require an device firmware implementation and there isn't any.

Michael

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Old 12th Aug 2021, 2:58 pm   #9
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Default Re: RAM / ROM tester

I have one too. I bought my PCB from the UK supplier 'Silicon-Ark' as they are only a few miles up the road who then hand delivered it.

Works really well, gets regular updates and tests a far greater range of SRAM/DRAM than say my TL866 or Wellon programmers

Regards

James
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