Amiga upgrades
Memory upgrade
You need to have:
- A500 with 0.5MB RAM(mainboard rev. ~5,6). with 4 memory chips (generic xxx4256-xx).
- 4 memory chips (generic xx4256-xx) from ISA video board, old 286. (Chips maybe called MN414256-10). Chips must be in DIP packacge.
- Solder iron (20..40W), some soldering stuff.
- Screwdriver. In some Amigas cross type in some Amiga is some weird screws...
- Some instrument to cut wires on printed circuit board (PCB).
Now you must:
- Disconnect all cables from your A500
- Open your Amiga, remove keyboard (do not forget how the keyboard is coonected), remove shield under the keyboard.
- Locate memory chips. They are same chips in DIP package. If you find 16 chips, you are unlucky and your Amiga is very old.
- Find free space near memory chips. You must find 4 empty places. In some Amiga PCB the holes are unfilled with solder in other - filled.
- Solder new chips in empty space. Check if you didn't short the pins and the first pin number is the right place.
- Connect cables to Amiga. You don't need to connect keyboard. Turn on the computer. If it starts, everything is ok. Don't check the memory - it is still NOT ENABLED, we are checking if our Amiga is still alive :) . Turn off your Amiga. If it is not working check:
- If memory chips are not hot, if hot -they are bad.
- for bad solder, shortened PCB track of chip pins.
- Locate jumper JP7A. It will be connecting 1-2 pads or not connected. Shorten 2-3.
- Turn on Amiga. If it starts, insert WB disk. Now you must have 0.5 CHIP and 0.5 other memory.
- Turn off you Amiga. Locate JP2 jumper (It must be near CPU, the biggest chip on PCB) Open JP2 1-2 connection and shorten 2-3. AND open JP7A. IT MUST BE OPEN, all 3 pads must be not connected.
- Turn on Amiga. Start WB. Now you must have 1MB of chip ram. NOTE: I tested it only with 8375 agnus, but I may work with 8372. I am in doubt about 8370/71...
- If it is working, now you are lucky owner of A500 with 1MB chip ram (A500+). If it is not working, you always can switch back all the jumpers and return to old configuration.
- I think that if you have 8375 AGNUS and if you plug A501 memory expansion you'll get 1.5MB or 2MB A500. I didn't tested it because I sold my a500 after this and CPU upgrade hacks and I didn't have A501...
That's all about easy memory expansion...
Now check how to make your a500 to run at 14MHz
IMPORTANT NOTE: you always can break something in your Amiga. So please be carefull
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