The 6502 has an 16 bit address bus, so it can access 64KB of memory, made up of RAM, ROM and I/O devices.
Address decoding is the hardware that enables the devices in that memory space at the desired address.

The basic address decoding is made up of a 74145, a TTL IC that decodes 4 bit to 10 bits, here used as 3 to 8 decoder. Te 74145 ha open collector outouts, so outputs can be tied together.

74145 function table

Memory decoder in the KIM-1

According the User manual this leads to the memory layout as shown above. Note the K0-K7 signals that are connected to the hardware devices such a RAM, and the RRIOTs.

Incomplete memory decoding
The picture above is a bit misleading. Since address A13, A14 and A15 are not included in the decoder, they are efectively ignored. The KIM-1 sees a maximum of 8K memory this way 000-3FF.

Why still using 16 bit addresses? In fact the higher address lines are ignored, so address 0000 is also address 2000, 4000 etc with 8K steps to E000.
And the vectors at address 1FFA are also found at FFFA, so the RESET vector works.

Decode enable

Further reading