Atom Gone Potty

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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BeebMaster
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Atom Gone Potty

Post by BeebMaster » Mon Dec 28, 2009 3:40 pm

I've just got the Atom out, hoping to try to persuade some machinery or other to let me record the screen output when all of a sudden I typed "CLEAR 0" and instead of normal text appearing, I got blocks of graphics instead. Now everything on the screen comes out as blocks.

Here's what happens as soon as I power on:

Image

That's normal, but here's what happens after pressing BREAK:

Image

The chips on the board, especially the RAMs, are running pretty hot. I've cooled it down and tried again but the same thing happens.

It's the same Atom I took to Console Combat in the summer, which was running quite happily for two days without melting. Has it finally had it?
Image

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IanS
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Re: Atom Gone Potty

Post by IanS » Mon Dec 28, 2009 4:15 pm

Looks like dodgy ram.

The second screenshot looks like it has the usual "Acorn Atom" sign-on message but with an extra bits set.

Re-seat all the ram chips, try swapping them round, they are all the same type.

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Re: Atom Gone Potty

Post by BeebMaster » Mon Dec 28, 2009 8:03 pm

That's fixed it, thanks very much!

All the RAMs are pretty hot, but two of them were especially hot (ie. Domesday SCSI board terminator HOT) in IC41 and IC43, so I took them out and moved two others and it's back to normal!

In fact they were so hot after only a few seconds of power that I burnt my fingers removing them. The rest of the RAM gets to this temperature after about 10 minutes, as well as most of the other chips including the 6502, so I'm a bit concerned that there is something else going wrong.
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IanS
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Re: Atom Gone Potty

Post by IanS » Mon Dec 28, 2009 8:20 pm

It's probably worth checking all the memory works ok.

Not very efficient, but does the job, the manual has a memory test prog -

http://www.xs4all.nl/~fjkraan/comp/atom ... 01.html#91
Section - 12.3.1 RAM Memory Faults

Depending on how memory you have will affect what values to enter.

#8000 - #97FF will test all expanded graphics ram.
if you set page to #82 and re-enter (or load from storage) the prog you can then test the main ram #2800 - #3BFF

to set page to #82 -
?18=#82
NEW

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