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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: 8bitbubsy on March 04, 2009, 03:00:41 AM
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I have this Rev 6A A500 with 4 empty RAM chip spaces, can I solder on 4 more of those to get 1MB? :-D
(http://img5.imageshack.us/img5/2600/92812323.jpg)
:flame:
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Yeah, but I think they do the same thing as a trapdoor expansion - and you don't get a clock this way.
Full details on this hack should be on Aminet somewhere.
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Also remember you can modify the trapdoor memory address to force a remap as "fake" fast RAM. :-)
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I did this mod years ago.
You may have to solder a pad as well to enable it. Soldering the chips will give you a total 1MB chip RAM.
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Yes. I did it to my Rev 6 a long time ago when I had a RAMboard, so I had 1MB Chip and 4MB Fast. Was nice.
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http://www.youtube.com/watch?v=swt2-JiLYt8
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My tuppence...
Use sockets. Nothing sucks worse than having to unsolder all those chips because you put them in backwards. Use low-profile types to allow the shield to fit back on without smacking onto the chips, although having an entire square-foot of heatsinking would be kinda neat...
Don't forget the caps (0.1uF) at the bottoms of the chips, right where the arrowheads on your photo are. These provide "decoupling" and filter any transient spikes on the power lines.
Check JP3, that four-pad box in the upper right of your photo. Looking at it as oriented, it should be jumpered:
1 0-0 2
3 0-0 4
that is, 1-2 and 3-4. This gives you the RAS/CAS signals to the second bank. If you check the pads and find none are jumpered to each other, I'd recommend installing a 4-pin header block to allow you to use standard pin-blocks for jumpering, so you're not having to use the soldering iron/X-acto® all the time. This, with the sockets, allow you to undo anything for testing purposes.
You can leave the caps in, though, so those can go in as-is.
You'll still need to set the JP2/JP7A jumpers to make the expansion into chip. Good luck!
banzai