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Copy file name to clipboardExpand all lines: README.md
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@@ -15,17 +15,7 @@ OpenAmiga600FastRamExpansion is basically a clone of [a RAM expansion produced b
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### Memory Compatibility
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The required RAM Type is 16 Mbit (1M×16) DRAM in the SOJ-42 package with up to 70-80 ns access time. It is 5v-only DRAM (not SD(!)RAM) often found in old 72-pin SIMMs, EDO chips might work or not. All chips having *8160* in their part number should be OK.
See [OpenAmiga500FastRamExpansion](https://github.com/SukkoPera/OpenAmiga500FastRamExpansion#memory-compatibility) for a compatibility list.
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RAM chips can either be soldered directly to the board or installed in sockets. While soldering the chips might not be trivial for the unexperienced, sockets for the SOJ-42 package are hard to find and not really easier to solder either, so the choice is up to you.
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Before soldering the CPU socket you will need to rework it a bit: you should sand down one of its edges, or it will hit resistor R102 that is present in REV 1.5 boards (at least). Thus try to fit it on the CPU (the large square chip with *MC68000* written on it) and see which corner it is. Make sure to match the correct orientation: one of the corners of the chip is cut and, if you look at the socket, one of its corners will match that.
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Besides that, most PLCC sockets have some sort of "stand-offs" on the bottom (which is going to be our top), which you are recommended to sand down, too. I also suggest to clean the CPU pins if possible, using contact cleaner or isopropyl alcool, as all sorts of gunk have probably gathered on them over the years. Let them dry well then. All of this should hopefully make the socket fit better on the chip.
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Besides that, most PLCC sockets have some sort of "stand-offs" on the bottom (which is going to be our top), which you are recommended to sand down, too. I also suggest to clean the CPU pins if possible, using contact cleaner or isopropyl alcool, as all sorts of gunk have probably gathered on them over the years. Let them dry well then. All of this should hopefully make the socket fit better on the chip.
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After you solder the socket, you can cut the bottom of it so that the window in the PCB continues through the socket. Most sockets will already have holes on the bottom that will make this operation easier. This will allow you to install a 14x14mm heatsink on the CPU, which might be a good idea since installing the board will somewhat reduce the heat dissipation capabilities of the chip. Make sure to use good thermal adhesive/glue, otherwise you risk to make the dissipation even worse.
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Normally it is not necessary to mount all the decoupling capacitors. I usually skip C4 and C7. Maybe capacitor C13 can be left out as well, your choice. R4 should be chosen according to the particular led you will be using for LD1. Actually you are free to skip LD1 and R4 altogether, if you hate power LEDs.
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After everything has been soldered, you will need to program the CPLD. Whenever you do so, **make sure to carefully remove the board from your Amiga, or you might risk damaging it**. Use the typical cheap *USB Blaster* clone you can find on eBay for the task.
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After everything has been soldered, you will need to program the CPLD. Whenever you do so, **make sure to carefully remove the board from your Amiga, or you might risk damaging it**. You can find the firmware files [here](https://github.com/SukkoPera/OpenAmiga500FastRamExpansion/tree/master/firmware), along with instructions on how to flash them.
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Finally, install the expansion in your A600: place it over the CPU with the correct orientation and push it down firmly until it feels solidly in place but don't force it.
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Before reassembling your case, I recommend to run [SysTest](https://github.com/keirf/Amiga-Stuff). Use the Memory option (<kbd>F1</kbd>), it must show 4 MB of Fast RAM. Then start the Memory Test (<kbd>F1</kbd> again) and let it run for 50-100 rounds: if it doesn't find any errors, you are probably good to go. If you get any errors, power off your computer and try to give the expansion a better fit, by pushing it further down or twisting it slightly back and forth.
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Before reassembling your case, I recommend to run [SysTest/Amiga Test Kit](https://github.com/keirf/Amiga-Stuff). Use the Memory option (<kbd>F1</kbd>), it must show 4 MB of Fast RAM. Then start the Memory Test (<kbd>F1</kbd> again) and let it run for 50-100 rounds: if it doesn't find any errors, you are probably good to go. If you get any errors, power off your computer and try to give the expansion a better fit, by pushing it further down or slightly twisting it back and forth.
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It might happen that the board slowly works its way out of the socket over time. To avoid this you can anchor it to the mainboard using the hole to the left of the CPU, which should align with one of the holes for the HD cradle legs.
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Note that, as already mentioned, PLCC sockets are not meant to be used this way, which means that the contact quality degrades a bit with every insertion or removal of the board. So, try not to remove it unnecessarily. If you find that the contact has degraded so much that the machine is no longer stable, replace the socket with a new one.
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Also, if you still have to register to that site, [you can use this link](https://www.pcbway.com/setinvite.aspx?inviteid=41100) to get some bonus initial credit (and yield me some more).
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Again, if you want to use another manufacturer, feel free to, don't feel obligated :).
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Again, if you want to use another manufacturer, feel free to, don't feel obligated :). But then you can buy me a coffee if you want:
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<ahref='https://ko-fi.com/L3L0U18L'target='_blank'><imgheight='36'style='border:0px;height:36px;'src='https://az743702.vo.msecnd.net/cdn/kofi2.png?v=2'border='0'alt='Buy Me a Coffee at ko-fi.com' /></a>
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### Get Help
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If you need help or have questions, you can join [the official Telegram group](https://t.me/joinchat/HUHdWBC9J9JnYIrvTYfZmg).
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