Memory

What do we use for accessing small amounts of data quickly?  Registers (32 in MIPS)

Why not store all data and instructions in registers?

Too much overhead for addressing; lose speed advantage

Register file can use 5-32 decoder or 32-1 MUX to select

Memory (RAM) is organized in larger quantities

Vcc, Vdd: voltages (5 volts and ground), necessary to power the chip, but do not affect logic

A9-0: Address input (10 bits)  Why 10 bits?

R/W': read/not write, selects read or write

1: read, 0: write

CE: chip enable, allows read or write; when 0, neither read nor write

also called chip select

D7-0: 8 bits of data read or to be written

may be bidirectional, or 16 separate lines (pins on the chip)

Where do the inputs come from?  CPU