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 Post subject: Tested Ramz
PostPosted: Wed Oct 05, 2022 3:00 pm 

Joined: Fri Feb 14, 2014 3:42 pm
Posts: 142
Location: Troy, NY
Chris,
Thanks for adding the tested RAM section, I've been waiting for this day for a while.
Dumb question: do you plan on going in the opposite direction? I have a Mongolian cluster-ton of hoarded 30 pin and 72 pin modules that I keep on hand for projects. I could fill a contractors bag (not that I would if they tested good :>))
Also, EDO modules/cache memory. I know... you could sell on ebay... blah blah, but it would be good to have an outlet moving forward if I needed to clear out quick because the wife threatens homicide.


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 Post subject: Re: Tested Ramz
PostPosted: Thu Oct 06, 2022 1:37 am 
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I’d love an outlet for 72 pin. I have so much there’s some stashed in every room. Much to the dismay of my family. Probably more 72 ram than vhs tapes.
But there is so much out there I doubt Chris wants to deal with 100 pound boxes of 72 pin ram. Lol.

I don’t know about EDO. The user population is so protective of the supply and price. I’ve seen literal fights at demo scene and swap shows over pricing it “too high”.
I’ve taking to donating extra to local stores. Though I keep a nice supply for my own retro systems.

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 Post subject: Re: Tested Ramz
PostPosted: Thu Oct 06, 2022 9:06 am 

Joined: Fri Feb 14, 2014 3:42 pm
Posts: 142
Location: Troy, NY
Right.
The thought of re-testing each module, using the appropriate systems to do so, is daunting enough to make me realize why they have been put away/hoarded for so long in the first place...
Other than keeping some for personal use, my recurring thought was to be the guy that tests and ebays them (probably sell 5 modules a year...) using a stand alone tester (they exist) but the prices on those bad boys are outrageous. The cost/benefit doesn't make sense unless I can snag one for cheap.
Lost, you have one laying around? I'll trade you for some cool stuff


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 Post subject: Re: Tested Ramz
PostPosted: Thu Oct 06, 2022 11:51 am 
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Pro tip:

Look in industrial and scientific. Not tech.
Look for rom programmer. Not ram tester.

Most rom programmers have a 72pin slot or two. Those systems will also test the ram.
Some require a rom to be plugged in to test the ram so you may need to track down a matching prom chip.
They tend to be in the $75-$200 range for programmers.

The other option is to simply grab an old computer. Which can be MUCH less.
The free program MemTest has been around since the 70s! You’ll find my posts filled with suggesting it.
It’s slow and clunky. It runs from a semi-graphical shell. Either CPM or Linux. As a boot and load program.

There isn’t a tech worth salt that doesn’t have a copy. Because it also tests hard serial transactions. Some CPUs, timings, rom/bios…! Hold down control or compose when it boots and get a mega menu of alternative tests in some more recent versions.

I found the best test rig for parts is very late xt/at boards from DG or DEC. Where everything is socketed. They support Intel, MOS, and Motorola components. With MemTest you can test nearly anything plugged in to the board.

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 Post subject: Re: Tested Ramz
PostPosted: Thu Oct 06, 2022 1:03 pm 
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More thoughts being awake again now.

There’s a lot of hobby machines from the 1980s that had modular boards.

The Apple 2 series has some good designs because they had the Intel comparability board sets. Pop in a 386 and a 72pin breakout board. Easy testing. There is a special version of MemTest you can grab from Old Software or the Internet Archive that works on apple // and /// machines.
Some Tandy machines from the early 90s are ver good too. And inexpensive.

The TI 99 with a breakout 8086 cartridge also supports 72pin SIMMs on the memory expansion peripheral.

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 Post subject: Re: Tested Ramz
PostPosted: Mon Oct 10, 2022 10:02 am 

Joined: Fri Feb 14, 2014 3:42 pm
Posts: 142
Location: Troy, NY
Right. I have the setups to accomplish this, and probably on ten machines at the same time, but it is what I'm trying to avoid doing.
With populating an actual MB, it's not just a matter of seeing if the machine powers on, you would have to properly stress the unit (run applications, etc.) to see if the modules are working to their full capacity. Wherein a stand alone tester would do this for you by applying the proper voltages and etc to simulate those conditions in a much shorter amount of time and effort.
I have boney fingers, but it's still a pain in the sack to pop modules in and out all day. The tester has a nice top loading form-factor. Maybe I'm just getting picky in my old age.


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 Post subject: Re: Tested Ramz
PostPosted: Mon Oct 10, 2022 10:39 am 
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Lol.

Ultimately there’s not much difference except the the load mechanism.
Stand alone testers are based on either a 68K or 80xx chip. Running the Unix 4 or an assembly kernel minim OS. Unless you’re looking near thousands, the rom based units for programming require binary or octal switching input. Which is why I switched to a computer for testing ram in the first place, a keyboard.

I know what you’re after. The answer is spend major bank for a self testing pre-programmed unit or use an interrupt switch to input commands to a tester.
I don’t remember the exact price but I paid close to $1500 for a used 12/16/18/24 programmer and it’s a pain to set ram testing for output to serial rather than pass/fail notices (one bad cell is a fail but still usable by 99.999% of people).
I prefer the Ti/99 and the Dyson Digital breakout because it’s a ZIF slot cartridge. I use Zdos with GEM and MemTest.
Programming a printout dump to terminal or printer requires about 30 minutes per chip. With the TI it takes a few seconds of clicking to start a test.

I have a 16/24 8088 programmer I’d part with that supports both 72pin and PCv1 DIMMs I don’t use much…
Depends on what the trade would be. Email me if serious. But we’re not talking an old laptop or something here. These are. Still, four digit machines.

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 Post subject: Re: Tested Ramz
PostPosted: Tue Oct 11, 2022 2:21 pm 

Joined: Fri Feb 14, 2014 3:42 pm
Posts: 142
Location: Troy, NY
Lost,
I like a good negotiation.
I doubt I have anything you want that you don't already have, but humour me with a list of things you want/need. And no, I still havn't uncovered any twiggy disks...
I have several Tandy 1000 models, Apple 2's up the wazoo and a stack of ti-99s (that I never use), so I'd be interested in discussing a breakout rig, seems like that could be a way to go, if you have any spare parts to build one.


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 Post subject: Re: Tested Ramz
PostPosted: Tue Oct 11, 2022 3:09 pm 
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The 99 was, and is, one of my favourites. Its cpu was powerful for the time. A full 16 bit system with complete parallelism in instruction counting.
It’s also extremely expandable.

The easiest way to to creat a tester with it is to buy an MOS cart off ebay. They are less common than the x86 and zylog cartridges but come with a rom socket inside the cart for drop in boot ROMs. Like the rom from an apple ][.
The cartridges tend to run around $50.
There’s two sets of stun pins inside as well.
These connect to the peripheral cards for the expansion box. Meaning you don’t need to shell out for the card bay itself.
30-pin 4 socket cards are the most common ram board for the 99 expansion but there are 72 pin 2 and 4 socket cards as well.
Ram cards are in the same price range as most conversion carts.

you also need a working 8” or 5.25” drive for the TI. Or TI’s EEPROM cart.

Just pop the cart open, plug a ribbon cable In To the ram card and the cart.
Download the rom image bin or disk image img from the MemTest 64 google code or gethub. Copy the file to the the disk or eeprom. (There’s steps to that, lol)
Then use TE on the 99 to copy the image to ram. Swap out the flash cart and plug in the the MOS cartridge. And transfer the ram to the rom in the cart.
That gives you a bootable breakout cart with MemTest installed.
Restart the system, plug in some ram (with the system on) and follow the prompts.

Another option is old Leading Edge computers which had power resist ram sockets and allow some level of hot swapping of all but sockets 0 and 1.

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 Post subject: Re: Tested Ramz
PostPosted: Tue Oct 11, 2022 3:25 pm 
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Quote:
but humour me with a list of things you want/need


Lol! A few million bucks?

I’m always after Lisa and gen 1 XL parts.
I see a full “Lisa” popped up on ebay for $3000 some but I don’t remotely trust the price on that. The last TRUE Lisa that sold was over over $16K. So I’m guessing a Gen 2 XL with a face plate swap. Same look and OS, very different board.

I need a cache rom for my Atari 5150 Pam prototype.

A 14 inch IBM disk cartridge?

A PDP 11 rom board with 2BSD.
So far i bought two rom cards off ebay claiming to be properly flashed and both were duds. I don’t have the time, patience, or skill to do a serial compile from one of my 16s. (Apparently nobody else does either!)

Just email me a few times over the coming months. We’re slowly cleaning and sorting. Once I dig out an old programmer I’ll ship it to you. Who needs a dozen rom programmers anyway?

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