The RRIOTs in the original KIM-1 contain 64 bytes of RAM each. The single RIOT in the PAL-1 has 128 bytes of RAM which are mapped to the same memory area as the two 64 byte RAMS in the original. When I add a second RIOT there'll be an extra 128 bytes of RAM with no obvious place to go on the memory map. Is the RAM in the second RIOT not mapped anywhere, or is it accessible in another address range?
Then I'm wondering about ESD sensitivity. I noticed that on the PAL-1 itself, all the pins on the MOS circuits either have pull-up or pull-down resistors to Vcc or GND, or are connected to the TTL circuits. That should make the board fairly insensitive to static electricity, since the MOS inputs can't build up any high potentials.
But on the second RIOT kit many of the RIOT's address and data lines are just connected directly to the input connector, so they are left open when the board is not connected to the PAL-1, and it seems like this should make it quite sensitive to ESD. Has anybody had any problems with this? Is the solution to always keep it connected to the PAL-1?