English Amiga Board - View Single Post - A500 rev6a chipRAM mods (1MB on motherboard)

Sim085 · 09 September 2019, 21:55

I have seen several ChipRAM mods but none which I can find actually results in a setup similar to an A500+ (1MB ChipRAM on motherboard and 1MB ChipRAM through trap-door expansion).

From what I can understand there are three ChipRAM mods that can be applied on an A500 rev6a motherboard. These are the following;

1. Solder 2MB of ChipRAM on the motherboard together with an A3000 Agnus as documented here. This makes the trapdoor expansion useless. All ChipRAM is soldered on the motherboard itself.

2. Modify jumpers JP2 and JP7 as documented here. This results in the 512KB ram in the trap-door expansion to be recognized as ChipRAM giving a total of 1MB ChipRAM.

3. Do number 2 above and buy a MegaChip. This gives a total of 2MB ChipRAM with 512KB on the motherboard, 512KB in the trap-door expansion and 1MB on the MegaChip board itself.

To my knowledge there are no other ChipRAM mods for the A500 rev6a motherboard. Therefore am I correct that there is no method how to get 1MB ChipRAM on the motherboard?

Or it is possible to solder an extra 512KB ram on the motherboard and configure this as ChipRAM but there is no Agnus out there which would then recognize 512KB/1MB ram in the trap-door expansion?

09 September 2019, 21:55	#1
Sim085 Registered User Join Date: Apr 2009 Location: N/A Posts: 962	A500 rev6a chipRAM mods (1MB on motherboard) I have seen several ChipRAM mods but none which I can find actually results in a setup similar to an A500+ (1MB ChipRAM on motherboard and 1MB ChipRAM through trap-door expansion). From what I can understand there are three ChipRAM mods that can be applied on an A500 rev6a motherboard. These are the following; 1. Solder 2MB of ChipRAM on the motherboard together with an A3000 Agnus as documented here. This makes the trapdoor expansion useless. All ChipRAM is soldered on the motherboard itself. 2. Modify jumpers JP2 and JP7 as documented here. This results in the 512KB ram in the trap-door expansion to be recognized as ChipRAM giving a total of 1MB ChipRAM. 3. Do number 2 above and buy a MegaChip. This gives a total of 2MB ChipRAM with 512KB on the motherboard, 512KB in the trap-door expansion and 1MB on the MegaChip board itself. To my knowledge there are no other ChipRAM mods for the A500 rev6a motherboard. Therefore am I correct that there is no method how to get 1MB ChipRAM on the motherboard? Or it is possible to solder an extra 512KB ram on the motherboard and configure this as ChipRAM but there is no Agnus out there which would then recognize 512KB/1MB ram in the trap-door expansion?