This week Retro Recollections upgrades the CHIP RAM on his Amiga 500 to 1MB and gives it 1.5MB of slow RAM with the great little affordable expansion card and adapter kit from BooBip.com
About The 2MB RAM Amiga 500/500+
This is a two megabyte memory upgrade for the Commodore Amiga models 500 and 500+. It is a modern replacement for the original A501 0.5MB (512K) upgrade from Commodore.
Add up to 2MB of memory to the machine depending on motherboard revision and Kickstart version (see below for details). Can provide both chip RAM and slow RAM in one expansion.
On the Amiga chip RAM is used for graphics and sound. Many games were written to use additional chip RAM to provide better graphics, sounds, music, higher resolution TV images and reduced disk swapping. Slow RAM can be used by workbench and many games also support this memory.
The upgrade can be fitted with a realtime clock chip (RTC) and clock backup battery (CR2032).
The upgrade consists of a memory board and an optional Gary adapter.
The memory board has the 2MB memory chip, logic, A500/A500+ jumper and RTC socket. The RTC socket allows an RTC chip to be fitted to an Amiga 500 if the user wishes. Amiga 500+ computers have an RTC chip fitted from the factory. The memory board fits in the “trapdoor” under the keyboard.
Installed without the Gary adapter, the memory board will act as a Commodore A501+ memory upgrade providing 0.5MB on an Amiga 500 and 1MB on an Amiga 500+.
The optional Gary adapter brings extra signals to the memory board. This allows more of the memory on the board to be used by the Amiga – more than the original Commodore upgrades. The Gary adapter must be fitted to access the full 2MB on your Amiga.
The memory board has an additional connector for optional jumper wires to the Amiga motherboard. These wires are required to get chip RAM and slow RAM at the same time. The wires must be soldered to the Amiga so only attempt this if you have the correct tools and are confident in soldering your Amiga.
The upgrade has been tested on Amiga 500 revision 3, 5 and 6A as well as Amiga 500+ computers.
How much memory is available for use depends on Kickstart ROM version, motherboard revision and Agnus (OCS/ECS) version.
The upgrade will work in any Amiga 500. However not all 2MB is accessible on the older machines.
Kickstart v1.3 (or greater) is required to use the Gary adapter. Older versions of Kickstart do not boot with more than 0.5MB of extra RAM. The Kickstart ROM can be upgraded on all Amiga machines. Revision 3 and revision 5 computers shiped with Kickstart v1.2. For more information see Kickstart Wikipedia.
An ECS Agnus (8372 or 8375) is required for 1MB chip RAM. The original OCS Agnus (8370 or 8371) found in revision 3 and 5 machines can only access 0.5MB. For more information see Agnus Wikipedia. Revision 5 A500s can be upgraded to a 1MB Agnus – search the forums for details.
A jumper wire soldered to JP2 and the Gary adapter are required for the full 2MB to be accessible.
The upgrade will work in any Amiga 500+.
Jumper wires and the Gary adapter are required for the full 2MB to be accessible.