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Terms in this set (28)
Define Memory Hierarchy
A computer system has a wide variety of storage devices organized in a hierarchy according to access time and cost
name the storage devices in the memory hierarchy
registers, cache, primary memory (RAM), secondary (auxiliary) memory like magnetic disk, optical disks (CD), magnetic tapes
In the memory hierarchy, what is the most costly storage device?
in the memory hierarchy, what is the fastest storage device?
What type of array is RAM?
it is a one-dimensional array of cells. a memory cell is a group of bits. each cell has a unique address
if memory address has k bits, then maximum number of cells addressable is
Define MAR (memory address register)
it holds the address of the memory cell accessed for read or write
in modern machines, a cell is a group of how many bits?
8 bits which equates to 1 byte
in modern machines, each byte has a unique...?
address. hence the term, byte addressable machines
How many bytes could there be in CPU registers in modern machines?
2, 4, or 8 bytes
What is a word?
a group of bytes
When a 32 bit CPU register is saved in memory, what is important?
the byte ordering
What are the two kinds of byte ordering?
little endian and big endian
define little endian
this is when the least significant byte of a 4 byte register is placed in a low address byte
define big endian
when the least significant byte of a 4 byte register is placed in a high address byte
Which machines support little endian?
Intel processors (IBM PC), DEC VAX family
Which machines support big endian?
IBM 360/370 family, motorola processors
What is the point of word alignment?
it makes hardware simpler
Words a often aligned to what?
a word boundary
in terms of word boundary, a 4 byte word must begin at an address which is a multiple of..?
What happens when a read operation is performed?
1. The control unit places the required address in MAR
2. A request for a read operation is made so it waits
3. The memory unit retrieves the requested information and places it in the memory data register
When the address provided is in the MAR, what is retrieved?
a group of bytes - it could be as many as 4 to 16 bytes
Define memory width
The number of bytes accessed in each memory read/write
What happens when a write operation is performed?
1. The control unit places the required memory address in MAR
2. The control unit places the required information in MDR
3. A request for a write operation is made so it waits
4. The memory unit places in memory the contents of the MDR at the provided address
Explain RAM 1K * 8
The memory chip has 1K addressable cells each holding 8 bits of data
To address 1K cells, how addresses do we need? in terms of bits?
10 bit addresses since 2^10 = 1,024 which equates to 1K
In terms of memory chip and modular design, what does the pin CS stand for?
In terms of memory chip and modular design, what does the pin RW stand for?
Read or Write
THIS SET IS OFTEN IN FOLDERS WITH...
Performance (from Patterson-Hennessy book)
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