1. First and addressing range to distinguish addressing space
Addressing range: a range of numbers, no unit;
Addressing space: the maximum capacity can be addressed;
example:
It has a capacity of 1MB memory, 32-bit word length, Q: byte addressing, addressing the addressed word range and a respective address range size?
If the byte addressing, the
1MB = 2^20B 2^20B/1B = 2^20
Address range of 0 to (2 ^ 20) -1, that is to say twenty address lines needed to complete the encoding of the 1MB space, the address register 20, the address range size is 2 ^ 20 = 1M
If the word-addressed, then
1MB = 2 ^ 20B 1 Word = 32bit = 4B
(Note: 32-bit word length, word refers to 1 = 32bit, this information is only useful when addressing word by word to say here is the storage word length.)
2 ^ 20B / 4B = 2 ^ 18
Address range of 0 to 2 ^ 18-1, which means we use at least 18 address lines to complete the encoding of the 1MB space. Thus the word addressed by the addressing range is 2 ^ 18
Addressing method:
Addressing range:
Addressing immediate: Direct put a number
Direct Addressing: A word length of
Indirect addressing: memory word length =? (Machine word)
Relative addressing: wordlength (near PC) A is
Based addressing:
Indexed addressing: machine word memory word length =
note:
Machine word: a CPU can process data bits, usually related to the number of bits of the CPU registers.
Word length memory: a memory in a binary code storage unit (memory address) of the stored bits, i.e. bits in the memory of MDR.
Instruction word length: Number of computer instruction word.
Data word length: computer data storage occupied digits.
Early computers typically: storing word length = data word length instruction word length =. Therefore, a desirable access an instruction or a data
With the expanding range of computer applications, three may vary, but they must be integer multiple of bytes.