In this picture, taken from the right hand side of the machine, you can clearly see the 2 MHz 6502 CPU (the 40-pin DIP in the lower right foreground), the 6540 system ROMs (the row of white 28-pin CERDIPs and black 28-pin plastic DIPs to the left of the CPU), and the 8K of RAM, which consisted of 16 6550 static RAM devices (to the left of the system ROMs). The long connector to the right of the RAM devices is the keyboard connector.
In later models, the 512x4 bit 6550 RAMs were replaced with the (then) newer 2112 512x4 bit RAM chips.