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tf_hh

A personal statement by tfhh - please read. Thanks.

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On 2/20/2021 at 8:11 PM, svenski said:

So Syscheck has arrived. Sys Check is reporting all RAM is bad. Not convinced by that but proceeded to swap out RAM - no change. Every RAM chip is reported as BAD. In the end I swapped the bottom most RAM chip again with a "new" RAM chip - same result.

 

So using 64K on the SysCheck and the Atari's OS I get a blue screen which then goes to the self test presumably because no keyboard is connected.

 

Does anyone know what will be causing a total RAM failure or perceived total RAM failure?

 

Well, are any of the Micron (MT) RAMs left on this 800XL? If so, exchange them all. This behaviour is explained in the Sys-Check manual already. Defects at the Micron DRAMs often inclines a disturbation of the whole memory address buss (address lines A0...A7 between DRAM chips and the both 74LS158 multiplexers), which have an affect to all other DRAM chips, not dependend if they´re faulty or not. Also a not so uncommon failure of these DRAMs is blocking the datalines after first access.

 

So first job is to exchange all of these nasty Micron DRAMs. If this doesn´t cure it, go ahead with exchanging chip-after-chip from the DRAM control circuit until Sys-Check fires up with only Dip-switch #1 set to on, #2 and #3 set to off (function block). One of the 74s might be bad and cause this fault. Here are the involved chips for DRAM control:

 

- Both 74LS158 right next to the DRAMs (can be removed without inserting new ones for a Sys-Check test as described before)

- 74LS51 below cartridge port and MMU (the 20 pin PAL chip) - This IC can be removed without inserting a new one if all DRAMs are removed for a test

- 74LS375 (this must be exchanged, without it the external Sys-Check didn´t get the R/W signal)

- 74LS14 (this must be exchanged, without it the whole computer won´t start)

- CO60472 Delay Line (This IC can be removed without inserting a new one if all DRAMs are removed for a test)

 

At last the MMU itself might be the culprit. Can be substituted by a GAL16V8, if you´re able to burn such devices.

 

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Thanks for this, really helpful and appreciated.  All the MT RAMs have been removed, so all new RAM.

 

Sys-Check is one impressive tool - whilst on this XL I haven't been able to get far yet, Sys-Check at least allows the computer to boot - which shows that there is still hope. 

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Another example of very poor shipping by usps. I ordered a headshell for a turntable from a man in Germany on 10/19/20. I received it yesterday!! It's postmarked 10/21/20. So the gentlemen was actually quick with the shipping. At one point Paypal automatically asked if I'd received the headshell, when I said no, it went ahead and started a refund. Now i'm trying to send the money back to him again.

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FWIW.  I find its faster to buy and ship items from the UK and EU than it ship domestically in Australia at the moment.  Try working that out!

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I'm sure we all have our horror stories. Shipping is a nightmare right now, worldwide, and no shipping company is completely immune, though some are certainly worse than others. Here's one of mine from last month.

 

6 days from St. Louis to Dallas, where it sits for who knows how long, before making it back to St. Louis 12 days later. 18 days to travel from St. Louis to Dallas, back to St. Louis, and at no point has it gotten any closer to my house! I can't remember for certain what this particular package was or when I got it, but it seems like I finally received it about a week later. St. Louis is only about three hours from Evansville! I still wonder why in the world it made the "quick" trip to Dallas at all. It's definitely not a normal hub or stop for my region. I'm assuming it just accidentally got sorted into the wrong bin. It's still pretty funny though, especially now that I've received whatever it was. Luckily, it wasn't like it was life saving medication or anything important.

 

 

 

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Edited by bfollowell
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Truly annoying Brian, I'm grateful I have nothing in the post or coming to me, I just see so many random people delivering especially Prime stuff but yet the delays remain. 

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Slowly, but one by one USPS "found" the parcels and deliver it to their recipients. Five parcels left from December 2020 and one from January.

 

Freshly shipping items to the U.S. are delivered in 2 weeks as nearly normal...

 

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@tf_hh That's terrible to hear Jurgen.  I've bought a few things from you in the past, SysCheck, Atari Spares, Atari 400 boards and all have arrived in a timely fashion.  You are a credit to the scene my friend.  Always very helpful and patient. I think that there needs to be understanding from everyone at the moment that with Covid and Brexit (which affects not just the UK but Europe too) there's going to be long postal delays from Europe to the rest of the World.  It's a sad day when a few people can't (or just won't) understand and just have patience. 😞

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tf_hh/Jurgen-

I have ordered from you multiple times and I've always received what I ordered. You, my friend, are Wunderbar! I will ALWAYS order from you.

 

We are still in this damn pandemic.  Patience is key.

 

I support you, Jurgen.  Keep up your AWESOME work! 

 

-Mike

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As mentioned previously, I ordered in February this year and got my stuff in 2 week.  Really not bad, especially compared to the horror stories of some others!  Also, very happy with the products.

 

It wouldn't surprise me if things ordered in December got mixed in with the Christmas shipping mess and are still in purgatory somewhere.

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40 minutes ago, Dr Memory said:

As mentioned previously, I ordered in February this year and got my stuff in 2 week.  Really not bad, especially compared to the horror stories of some others! 

Yes, it made it all the more demoralizing hearing about people that ordered a month or two later getting their shipments while some of us were still waiting in the dark. It just seems like a big batch of orders shipped in November and December got hung up somewhere and took forever you get dislodged. Luckily, some of the later orders seem to have bypassed that whole snag. Hopefully, things are a little more back to normal now.

 

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Miracles happen... today I got the last outstanding feedback from all parcels on their way to the USA: Received. Finally. Wow 🙂

 

So it seems that everything went mostly normal. The last five parcels to the USA took less than 2 weeks or exactly 2 weeks, what is pretty normal.

 

Last chapter read. Book closed.

 

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Congrats Jurgen....

 

Common sense and decency returned..

 

Keep up the outstanding service....I need more sweets :)

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3 hours ago, tf_hh said:

Miracles happen... today I got the last outstanding feedback from all parcels on their way to the USA: Received. Finally. Wow 🙂

 

So it seems that everything went mostly normal. The last five parcels to the USA took less than 2 weeks or exactly 2 weeks, what is pretty normal.

 

Last chapter read. Book closed.

 

Yayyy!!
 

And now back to work on that exotic, dual NTSC/PAL CPU card for the 800, with Sophia-2 integrated on-board, for finally bridging the old and new world!!!

 

😀😀

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Great news!  Maybe shipping time will return to something near normal for a while.  Only around 8 months until Xmas holiday purchases start up and overload the postal system again!  🙂 🙃 🤪 😆 😂 🥴

 

Seriously though, I hope all the chaos from 2020 will be over for good by that time.  Best of luck!

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9 hours ago, tf_hh said:

Miracles happen... today I got the last outstanding feedback from all parcels on their way to the USA: Received. Finally. Wow 🙂

That was me.  Hurrah!  Now I just need to find some time to finish up working on that problematic 600XL motherboard of mine.  :)

20210318_193249.jpg

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