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CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Thu Nov 22, 2018 9:27 am
by rubber_jonnie
It's a REV. 2B and it has a piggyback RAM expansion.
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I will update when I get a chance to give it the once over and power it up.
Anybody else think those wires look like telephone cable?
Re: CO700115 with Piggyback RAM expansion.
Posted: Thu Nov 22, 2018 10:12 am
by troed
rubber_jonnie wrote: ↑Thu Nov 22, 2018 9:27 am
I can't quite make out the revision, I will update when I have it apart again, but it has a piggyback RAM expansion.
Anybody else think those wires look like telephone cable?
Very very early motherboard - no filters.
And yes, that's typical extracted wires from a telephone extension - I've used them as well (single core, nice stiffness) for similar work. Might even have used them for my own piggyback extension IIRC
Not an official Atari upgrade, never seen them using them.
Re: CO700115 with Piggyback RAM expansion.
Posted: Thu Nov 22, 2018 10:18 am
by rubber_jonnie
troed wrote: ↑Thu Nov 22, 2018 10:12 am
rubber_jonnie wrote: ↑Thu Nov 22, 2018 9:27 am
I can't quite make out the revision, I will update when I have it apart again, but it has a piggyback RAM expansion.
Anybody else think those wires look like telephone cable?
Very very early motherboard - no filters.
And yes, that's typical extracted wires from a telephone extension - I've used them as well (single core, nice stiffness) for similar work. Might even have used them for my own piggyback extension IIRC
Not an official Atari upgrade, never seen them using them.
Whoever did it seems to have known what they were doing, as it looks quite neat. I'm assuming it's an upgrade to 1MB, but won't know until I get it running. According to exxos, who I bought it off, it powers on but doesn't boot, so I may have work to do before I get any more detail on it. Guessing it will have a pretty low ROM version.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Sun Nov 25, 2018 12:27 pm
by rubber_jonnie
Taken apart this morning, not powered on as yet.
Here is the other end of the telephone cable:
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Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Wed Nov 28, 2018 9:27 pm
by rubber_jonnie
Looks like this board has a memory problem, powers on and gets a white screen with blotches on it. Time to buzz out the lines and/or remove the piggy back ram.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Fri Dec 07, 2018 5:06 pm
by rubber_jonnie
So piggyback RAM expansion is now gone, And I have adjusted the MMU PLCC socket springs so that they are making proper contact with the MMU.
I might just do a quick article on adjusting the springs in a PLCC socket, as this is the second machine that I've had that has benefitted from it.
I also had to fix 3 cut tracks from the MMU too. Thank you kynar wire for being so fine
But, it lives again:
- It_Lives!.jpg (333.03 KiB) Viewed 7527 times
Test cart shows the remaining RAM is good, and I'm looking at TOS v1.0.
If I want to add more RAM in the future, I have a 2meg board that would do just nicely, but for now I'll take this as a win.
And as for the mouse/joystick port position, they are SOOO much better on these earlier machines, not sure what Atari were thinking when they slapped them under the keyboard. Also odd, but the mouse doesn't work if there is no keyboard plugged in. Go figure.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Fri Dec 07, 2018 5:15 pm
by exxos
rubber_jonnie wrote: ↑Fri Dec 07, 2018 5:06 pm
I might just do a quick article on adjusting the springs in a PLCC socket, as this is the second machine that I've had that has benefitted from it.
That would be useful!
rubber_jonnie wrote: ↑Fri Dec 07, 2018 5:06 pm
Also odd, but the mouse doesn't work if there is no keyboard plugged in. Go figure.
I assume it needs the keyboard chip to convert the data from the ports into serial for the ACIA, which is why the connector is so large.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Fri Dec 07, 2018 5:25 pm
by rubber_jonnie
exxos wrote: ↑Fri Dec 07, 2018 5:15 pm
rubber_jonnie wrote: ↑Fri Dec 07, 2018 5:06 pm
I might just do a quick article on adjusting the springs in a PLCC socket, as this is the second machine that I've had that has benefitted from it.
That would be useful!
I shall do one at some point then
rubber_jonnie wrote: ↑Fri Dec 07, 2018 5:06 pm
Also odd, but the mouse doesn't work if there is no keyboard plugged in. Go figure.
I assume it needs the keyboard chip to convert the data from the ports into serial for the ACIA, which is why the connector is so large.
My thoughts too. It just behaves really weird with no KB.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Tue Dec 11, 2018 9:10 am
by rubber_jonnie
Damn, something is not right, after cleaning up the legs that were soldered onto the existing RAM, I'm getting the same screen corruption and its not booting.
Magnifying glass out to see if the MMU has any dodgy connections at the socket, plus a clean of the pins, and if there are any solder whiskers left over.
Looks very like a problem I had with an STFM that showed garbage on screen and wouldn't boot, and that was a couple of address lines that weren't connecting all the way through, so a buzz of all the RAM chip lines may help.
May also be a problem with the lines that were cut that I had to repair, so will look at those again.
Re: CO700115 REV. 2B with Piggyback RAM expansion.
Posted: Mon Dec 24, 2018 4:06 pm
by rubber_jonnie
Well, all the old RAM is removed, and a SIMM upgrade installed on the MMU and Shifter, and she lives again. Very happy to be looking at this desktop right now
- 2018-12-24 16.05.11.jpg (4.67 MiB) Viewed 7331 times
