Chip and Fast RAM

What is Chip RAM?

Chip RAM is RAM that can be accessed by the Amiga Agnus or Alice chip, as well as by the Central Processing Unit.  It is where the sound samples that are played by Paula are stored, it is where the data that makes up the display is stored.  The contents of Chip RAM can be read and written by both the CPU and the custom chips (via DMA access with the Agnus or Alice chip), however while it’s being accessed by one, it can’t be accessed by the other, the custom chips have priority over the CPU.  This means that if there is only Chip RAM in a system, there will be times when the CPU has to wait to access it, slowing down the systems CPU.

What is Fast RAM?

Fast RAM does not have the limitation mentioned above, but it can’t be accessed by Agnus or Alice, it can only be addressed by the CPU.  Thus, simply adding Fast RAM to any Amiga that only has Chip RAM can potentially speed up the machine.