About one million bytes. About one billion bytes. Each byte of main memory has a unique address. Main memory consists of a very long list of bytes. Each memory location can store any number of bits.
Memory addresses are positive integers starting at zero.
It can write 8 bits to a byte in memory, and it can read 8 bits from a byte in memory. It can erase a byte in main memory, and it can read a byte of main memory. It can add the value from main memory to a sum, and it can print the value on the monitor. It can write the byte to secondary storage and it can read the byte from secondary storage. A file is a section of main storage used to store data.